Chevy 6.5 Turbo Diesel REVS Out of CONTROL?! (Part 2 - Didn't see THIS Coming...)

Based on the DATA collected, it looks like the PCM is ramping up the Fuel Control Solenoid and causing massive over-fueling and HIGH RPMS for NO REASON!
Also, the cold-start Coolant temperature is being reported incorrectly, showing about 100F too HIGH.
Is the PCM going NUTS??
I found a replacement PCM on eBay....
Let's plug it in, and see if anything changes...
PLACE YOUR BETS NOW!
IVAN'S PICO WAVEFORMS:
drive.google.c...
GOOLOO 4000 AMAZING JUMP STARTER:
www.amazon.com...
Enjoy!
Ivan

[@I_Do_Cars]

What a bummer for the owner. I hope I can pay him for the core to help negate some of the financial burden of an engine replacement. I don't see enough of these old 6.5's to get my hands on an engine I would trust. Really bad deal for everyone involved. I love older cars just as much as the next guy but sometimes the diagnosis and part availability make them a bit more cumbersome to own. You did everything you could Ivan!

[@californiacruisin2048]

I LOVE THIS GUY’S CHANNEL! GET HIM CONNECTED WITH THE OWNER!

[@meenie79]

My wife calls you phaser guy because you speed up the vid while impacting out bolts. Keep Missouri salvage alive! I hope you get this engine core.

[@konstantintomilin1826]

Thanks to Eric and Ivan, I saw two engines blow up in a single week.

[@johnlarkin549]

At least you didn’t fix it for naught it’s fu#% 🤣

[@lvsqcsl]

I really enjoy this guy's channel and watch it often.

[@jamesspash5561]

Once had a customer bring in a DOA 240Z to diagnose an engine knock. The knock was on top not in the base.While trying to narrow it down at an idle,it locked up. Spun a con rod bearing, the bottom bearing shell had spun up between the crank and the upper bearing half. The knock up top was the piston hitting the head. The customer screamed and yelled we ruined his engine and we were going to pay for it. He knew it was bad and was looking for a free fix. We towed it to his house. That's all the free he got.

[@rogerstlaurent8704]

This is why repair shops don't work on stuff like this anymore they just tell you to get the F off my property in a polite way

[@sitdox]

Had same on Hyunday Santa Fe 2.2 diesel was knocking at the top customer brought another so called mechanic and tried to contradict me so pulled injectors out and photographed valve imprints on the pistons with borescope then he finally shut up and paid additional investigation fee 😂

[@KStewart-th4sk]

That's the kind of a-hole that deserves some missing teeth. And the same kind of a-hole that will go around bad mouthing you. These days it is 10X as bad because now they can do it on social media. Glad the owner of this Chevy Diesel had both brains and ethics.

[@slomotrainwreck]

There was an news article out recently about the auto technician shortage and how techs are leaving the trade, I suspect customers like that 240Z owner is part of the reason why.

[@TheFleetz]

Not your fault Ivan. You can’t make an omelette without breaking some eggs. You were methodical and analytical throughout however can’t be blamed for tipping what was always most likely the outcome by applying your talent and skills to try and locate the issue. I do not see a fail on your behalf….your honesty is testament to your character! 👍

[@rogerrocco5211]

Big disappointment for you because you care about your work. That’s beautiful to know that you are dedicated to doing the best work possible. Integrity, honesty and dedication are mantras for success! Bravo and congratulations for your achievement and success!

[@MrTonyPiscatelle]

I was getting my popcorn ready and then BAM ! right in the face with the terrible news that a Chevy has passed away. Oh me oh my ! But I could hear the rod knocking earlier in the video-- I just knew it was not long for this earth.

[@throttlebottle5906]

yeah, she started hammering way early on, that noise was sure not valve/lifters.

[@williamthompson2222]

I was thinking the same thing you, cold starting that beast and going from 0 rpm to 2000+ in a flash and the owner driving it in that condition for weeks?! That was a grenade waiting for the pin to be pulled. You did everything you could. It's sucks to lose, but not your fault

[@kevin9c1]

Sure but the owner probably didn't attempt to rev it much in park or neutral. He would have put it in gear and then no possibility of slamming into the rev limiter like that. I don't blame Ivan though. That was part of the diagnostic process.

[@wwdiesel]

Ivan, you win some, you lose some, ah but the experience you gained in the process, invaluable, and you will never forget. Rest in peace old Chevy!

[@rodneymiddleton9624]

That's the unfortunate end for most all of them. Thanks Ivan!

[@randyr.parker2698]

Hey, you can't win them all. It's a shame we don't know what was really causing the problem though. Diesels can be hard to work on. Just something to keep in mind, the 'one and only' electrolytic capacitor (that I could see) in that control module can still be bad just because it's not leaking, and also the replacement from ebay is still 29 years old and have a bad capacitor also which would more than likely cause the same conditions. Unfortunately we'll never know. I don't think a lot of people realize how VERY important it is to have good clean voltage in these circuits, Crap in, crap out. Good video anyhow! 👍

[@bobwilson758]

I did not realize it was you at first - was about to click off , then saw your call sign ! Ooo wait , stop ! I always watch your videos -- pine meadow ? I am probably wrong - however , I like your Committment to your jobs . You obviously received proper training as a young man , and You have taken it from there with your attitude and knowledge . Refreshing to see your drive . Interesting videos and generally good results ! Good man ! Back when I was a young tech . I would have been proud to work with you . Thanks , Old GM . --UPS technician . See ya ( Retired )

[@JohnDoesGarage]

Maybe you did this test and I missed it, but I doubt it would have made any difference. Measure the signal from the temp sensor at the PCM to see if it matched what it was at the sensor? I watched a video where Scanner Danner was talking about technicians need to be compensated regardless of the outcome. He was on a service call to a shop that couldn't figure out what was wrong with a truck but the truck didn't act up while he was troubleshooting it. You have a lot of money tied up in your tools and equipment, not to mention that value of the knowledge you possess is priceless. Very few people can do what you do, and that is worth something. IMHO.

[@HollomanUFOLanding]

I feel for you man. Your disappointment & upset is very palpable in that video, but that's because you care about your work so much. You can't win 'em all, Ivan, good on you for giving it 100%.

[@tonep3168]

Feel for you Ivan. Not nice when you can’t do your job and then the thing dies in the process.

[@PineHollowAutoDiagnostics]

It went from slight knock to hole in the block in three ignition cycles 😪

[@jackiemay9471]

@@PineHollowAutoDiagnostics as soon as you heard it knock turn off and tow it not nice feeling destroying some ones engine

[@williamkelley7654]

@@jackiemay9471 By the time the knock was there it was already junk.

[@jackiemay9471]

@@williamkelley7654 but the conrod was nt through the block

[@jeffco908]

@@PineHollowAutoDiagnostics Did you ever check for the resistor being in the PMD connector housing?

[@redtopberries]

Hey Ivan props for showing the good, and the bad. It happens. At least The customer was understanding. Still curious what that coolant temp sensor was up to tho...

[@jordanboulay3780]

its nice when the owners understanding and not trying to blame ya for something out of your control you know when it leaves your shop not fixed its got major issues

[@whyknot4409]

Worked on these engines when I first started doing Fleet maintenance 25 years ago on 1 ton box trucks .( bread trucks ) They were automatics. When they failed we converted them to Cummins 4bt with stick shift . We had manual trans ,clutch pedal ,linkage springs all in stock.

[@GregoryGlessnerViolin]

The sound of that engine brought back some bad memories 😢 Even if death of a customer project doesn't end up being a hit for business, it's still personally a difficult thing to bear.

[@joseluisccoyllollacsa8902]

Hi Ivan, greetings frim lima - PERU, i see how much time and brain you put in that diagnostic, its sad for you and more sad for the customer that his engine died in the search of solution, Thanks for your video 😁👍☝️💪

[@johnclamshellsp1969]

Back in my dealer days, I replaced hundreds of those aluminum tin box ECM's. Take the butt end of long screwdriver and tap like a pool stick. Watch results. They fail every time. Bad idle, stalling, wrong data values, codes that make no sense and so on. The ultrasonic soldered connections became loose.

[@petermccoll469]

Than was unfortunate, at least the owner understood. Very nice diagnostic procedures.

[@GreyRockOne]

A gallant effort.. Thanks Ivan!

[@lvsqcsl]

As you correctly stated, Ivan, it would be impossible to determine the issue with the revving without starting the engine. The owner can view this video to know what you did if he/she has any questions. We don't get to see this often (the last time I remember seeing anything remotely like this was a "Halloween Special" you did 2 years ago on an old Ford Probe with transmission issues) so, it is indeed a learning experience for all. GREAT VIDEO!

[@Z-Ack]

Sounded like it needed the pump rebuilt..when they rev out like that and is having fuel issues is usually when they either blow up or run off then blow up.. but there’s a reason why they pay diesel technicians more than mechanics.. its a specialty trade.. the guts of a diesel can get tricky and unless you know than your only guessing..

[@manual6speed]

Here is a small gift

[@PineHollowAutoDiagnostics]

Very much appreciated! 🙏

[@volvo09]

Very nice! 👍

[@-ERIC-]

Had the exact same problem years ago, someone had put 2 gallons of Gasoline in at the pump by mistake then topped it off with diesel, thinking it would dilute it, weeks down the line the engine had exactly the same issues with run away at start, it began to run away on a test drive so I held it back on the brakes hoping it would stall and snapped the crank. Only after did they tell me about the gasoline being added wrongly.

[@brianw8963]

I retired my last VW diesel about 8 years ago, of the old rabbit era. They used to recommend adding 10 or 20% gasoline in cold weather, it was in the owners manuals for the diesel’s. I never tried it, but it was in their owners manuals. Of course those were old school mechanical with no electronic’s. Also, when things got down around 0 or lower, we used to put 5 gallons of gasoline in the tanks of the heavy equipment machines and never had any problems, though admittedly diesel was not the same in those days.

[@snoopyshea]

Awesome! I've been waiting for part 2 since a few hours - Thank you Ivan!!!!!!

[@williamwhite9767]

Dang! Two big disappointments, one the engine blew and the other you never found out what the problem was! I feel for you Ivan. These things happen sometimes especially working on very old vehicles.

[@brycelund7155]

He did find the problem it was the fuel solenoid in the injection pump. It needs an engine and a new injection pump that’s the diagnosis. If the customer brought it to Ivan right away maybe there would be a better outcome but who knows.

[@KStewart-th4sk]

@@brycelund7155 He never said that the fuel solenoid is definitely bad. The fuel solenoid is easily replaced on this 6.5 injection pump. Towards the end of the video, he didn't even say that the pump was definitely bad. Only at the end did he say the engine has to be replaced and a new injection pump. BUT that is basically a given, if someone is rebuilding the engine itself, either that injection pump should be tested at or preferably torn down, inspected, overhauled, calibrated, at a shop specializing in diesel injection pumps.

[@brycelund7155]

@@KStewart-th4sk The diagnosis: engine needs to be replaced along with the injection pump. Thats what Ivan said in the video.

[@robbflynn4325]

It's like taking a sick animal to a vet, hoping for a diagnosis and cure and getting the opposite. The engine had very low miles for a diesel, so you wouldn't expect it to throw a rod like that. It's great that the owner understood the situation and a nice gesture from you not to charge anything.

[@JohnIsett]

Have to admire your perseverance and can-do attitude, Ivan. But I'll have to admit I wouldn't have taken this job--the truck was filthy, inside and out, rattled like a rusty scow, and really gave off "I couldn't give a s***" vibes. That said, it was bound to be an interesting YT video. Well done attempt, and nothing to be embarrassed by. (I look forward to Eric's tear down! It'll be a great Saturday night!)

[@KStewart-th4sk]

Some people actually buy a truck to work with unlike the slick haired boys, who might go 4-wheeling on a weekend, when they aren't cruising. Now they got the TONKA TRUCK beds that are useless to a "real working man". This truck has been working since the mid '90's.

[@JohnIsett]

@@KStewart-th4sk As they say, you can tell the quality of the craftsman by the condition and quality of his tools. I wonder what you think the house should look like of the owner who makes that their place of work? But I do agree there are many faux pickup truck wannabes. Best wishes.

[@punkhead4312]

So glad you and I Do Cars know each other, I watch both channels regularly. Hope to see the teardown!

[@williegillie5712]

I just worked on a 2006 VW Passat with an idling problem. I got lucky and found rail pressure target value and actual pressure were way different. A new Pressure sensor took care of the problem. The previous owner put an aftermarket radio in and there were plenty of network issues because of it. It ran smooth and idled fine after replacing the fuel pressure sensor. I don’t envy that guy that owns that truck.

[@brianw8963]

Ouch. Wasn’t expecting this ending. Heard that rattle earlier in the video, but thought it was an exhaust rattle. As the saying goes , “ manure happens” , something like that anyway. Too bad it wasn’t a 5.7 gas, I could have helped out . (92 5sp.) 👍👍🇺🇸

[@paulbrown3180]

Too bad you did not Google this issue earlier before engine failure , I replaced over six hundred pumps under Warranty and who knows how many customer pay jobs , the Warranty pumps I kept in a log book just in case somewhere down the road a GM auditor had issues and wanted to charge back the dealership somehow . End of the story is my Service Manager and dealer owner had to sit through three GM Warranty auditors go through every injection pump/vacuum pump /fuel lift pump / turbocharger and engine assembly replacements for five years , dealer owner apparently losing his mind over the possible charge backs to the dealer . One of the auditors came to speak to me in the end , they could not find one dime to penalize us . The key for every tech is to document every detail /voltage reading / OHM resistance reading / fuel pressure and fuel quality . The more detail on a work order customer or warranty , the better

[@ricfair9919]

Ivan great diagnosis! You are Lucky your customer is not blaming you, by saying "was not like that before" Would of been good to get to the bottom of the failure. These older cars/trucks take up so much diagnosis time which sometimes cannot be charged for.

[@hasanvolkan4906]

This episode is why I love watching your videos, you have no problem airing the failures as well as the sucseses

[@fredautos]

Oh Ivan I feel Your Pains, but that's how it's goes sometimes!..

[@Sandmansa]

What a turn of events here. I'm sorry to see it but these things do happen. I once had a customer tow in a 2004 Volvo XC70 with a complaint of a grinding sound from under the hood. Get it off the tow truck and start it up. Sure enough, it's making a grinding noise from the timing cover. I run back around to shut it off and the engine shut itself off before I could. The grinding noise was the timing belt tensioner ripping through the cover. And it just broke off in less than 30 seconds while in my care. All 20 valves bent in an instant. As luck would have it, the customer was already prepared for the worst. They agreed to have the head rebuilt and all new timing set replaced.

[@mtebaldi1]

I commend your tenacity and perseverance in diagnosing this 6.5 Ivan. I know your motto is Never Give Up.

[@kevin9c1]

I've never seen or heard a 6.5 fuel cut at 4,000 rpm like that and now I've seen it like 15 times. That's something.

[@arcadeuk]

You've never watched zip ties n bias plies?

[@kevin9c1]

@@arcadeuk Apparently not enough.

[@calholli]

@@arcadeuk I've never seen him run a chevy diesel.. He usually only runs 7.3L's and cummins.. in the smaller trucks. but it's not like I've seen all his videos, to be fair.

[@vg3430]

Yeah…Ivan’s constant starting and red lining a cold diesel (for no apparent reason, he already has his data). Who knows how many times he did this off camera. Many of us told him in the first video it was the injection pump…but he kept up with his “you can’t diagnosis this without a 4 channel scope” ego. Sad for the owner.

[@calholli]

@@vg3430 They can handle a couple of red lines.. The engine had horribly old sludge looking oil on the dipstick.. and if they neglected the oil like that over years of use.. then it was already on it's last leg anyway.

[@yachtsteve]

I appreciate that you post your fails as well as your success's

[@classicwefi]

I had this happen on a customers Astro van 4.3 that had a bad crank sensor that was causing severe spark knock. So I replaced the sensor and did the cam crank relearn revved the engine to fuel shut off with the Tec2 took it for a test drive and it started rod knock on the test drive fun times 😢

[@PineHollowAutoDiagnostics]

Dang 😢

[@bairfamilyfarm1336]

Check the coolant temp sensor resistance at the PCM. May be a wiring issue, as for everything else I haven’t a clue.

[@major__kong]

Bad wiring, maybe bad ground. Or maybe it's a common failure in the PCM. It didn't seem to be this engine's problem, though.

[@ChrisWilliams-pu8pj]

As always...Dead Honest! Love watching you for that reason!

[@zx8401ztv]

So the engine was screwed way before the truck came to you. Not your fault Ivan. You could have written in big letters " KEITH " on the bonnet, that would have Frightened the crap out of that engine :-D

[@nevillegoddard4966]

Dang it this 6.5 was probly dead already before you got it! Don't feel bad Ive, you're still the master diagnostician to me mate! The best I've ever seen.

[@aciddiver1978]

The engine may have lacked proper lubrication when coldstarting on 2000 rpm and up.

[@stevenlatham4397]

The sad photo montage at the end… We’ve done so many 350-454 swaps in those trucks that I can’t even count. There’s even a few Cummins swaps running around in my area. The guy got pretty lucky getting 160,000 miles out of it, we’ve done them on trucks that only had 65 to 85,000 miles.

[@KStewart-th4sk]

Seems to me my co-worker had between 2-300 thousand KM on his 6.5 and had never had any trouble with it until that fuel module finally failed and he was having it relocated. This is in Western Canada, so he started it on some damn cold winter days to go to and from work. Minus 20 or 30 degrees lots of days and even colder sometimes. I had a 1991 VW Turbo Diesel and a 3 HR. round trip commute daily. When i got T-Boned by an a-hole running a red light, it was totaled. I then got an even older '86 VW TD and did the same drive for many years. My '91 VW had 698, 714KM when it met its end and it had been still running strong.

[@stevenlatham4397]

@@KStewart-th4sk 200,000km is only 124,000 miles…

[@10100rsn]

Could re-seat the EEPROM if its in a socket. Also, that yellow electrolytic capacitor on the board is pretty suspect. They have a shelf life and will go bad even if they seem fine. Like a car battery, it might test the correct value at voltage but while in operation it doesn't perform well in circuit.

[@ecaparts]

What a turd-sandwich! Such an unfortunate ending but this is reality. Can’t win them all! Thanks for posting this, Ivan!

[@warddc]

Wow both you and Eric blowing up engines now. Nice! 😁

[@tonyedwin9042]

PCM were pretty common in them back in that era. Usual issue was stalling when hot and not restarting ( not as common as the driver module)

[@markricketts-qm6xu]

the pump mounted driver module was the real problem but it is a real pia to remove so most would leave it there and put on a remote driver module, The problem is there is a fuel control resistor that goes into the new module over the pins on the driver plug, It has to be transferred from the old module to the new one, it is next to impossible to get it out of the old module without removing the module from the pump first. A lot of people didn't know about the resistor and had this same result as Ivans truck. I could see the pmd was still on the pump so it is very likely thats what happened here

[@tonyedwin9042]

@@markricketts-qm6xu never seen one do what his was doing.

[@tonyedwin9042]

Also I will give it to Ivan for having the courage to show this video. More about the reality of the automotive profession and pitfalls we deal with on a day to day perspective.

[@markricketts-qm6xu]

@@tonyedwin9042 I have, I replaced the injection pump with a used one and it did the same thing but before installing the pump i removed the pmdm and connected the remote module the owner had mounted behind the front license plate, it was hard to see but the resistor was not in it, A lot of pumps and ecm's were replaced and trucks scrapped because of this mistake. This resistor controls the fuel solenoid in the pump and is extremely important. you can buy new resistors but really should use the one that came with the pump as they are matched to each other that is why they don't come with the module

[@PineHollowAutoDiagnostics]

​@@markricketts-qm6xuthat is very interesting! Didn't see any mention of this funky resistor anywhere in service info 🤔

[@mrcogginsgarage7062]

Sad but you can't win them all Ivan ,was well toasted before you started,interesting to follow your process though.

[@timholderle9529]

Hated to see that but appreciate that you were willing to show us that not everything is fixable. It's easy to be the hero and find the solution. Not so easy to show when things don't work out.

[@ischmidt]

I hope this does make it to Eric. I wonder if the eBay PCM was also bad. I know some desktop computers from that era need to be "re-capped" because the capacitors leaked, and the leaked electrolyte causes wild random symptoms. Giving the board an isopropyl alcohol scrub and/or a full water bath is often necessary to clear all of the issues.

[@rrotwang]

Could be a batch of bad pcms

[@jessicav2031]

Well, this story is certainly depressing! I sure don't blame you for the kaboom, Ivan, and I really commend you on the bravery of uploading this video anyway rather than just deleting it. I have a couple lingering points though. Apologies in advance for the long reply 😅 First, I think the 2000RPM fixed idle is a kind of giveaway/red herring. I've never done anything with a diesel, but this appears to run an identical system hardware-wise to the TBI SBCs of the era. My partner and I own several, and me being and EE and him being an embedded firmware engineer, of course we studied the design a bit. The cause of the high idle I think is a flag in the firmware GM calls "stall saver". When the ECM detects engine response is poor (specifically iirc when actual idle speed goes below table target) it sets the stall saver flag, which forces the idle to a permanently high value. Note that the stall saver flag is reported in the status flags reported by a data stream request, but your scan tool probably doesn't show it since it is a "status" flag not a "malfunction" flag. (It is the 4th byte, bit #4, for TBI. Both the protocol specs and most of the firmware sources have been leaked over the years.) ALDL engines didn't really have codes, they were more like status bits. Other bits in the same byte are things like AC request, various closed loop conditions, power steering loaded, etc. I **think** the reported "desired idle" is unaffected and that is just the table value based on baro, ECT, P/N/D, and AC compressor state. So this would be consistent with poor response from the fuel control system. Second, I seriously doubt the incorrect ECT is a double computer fault (though it is possible your scan tool is misreporting the value by applying an incorrect formula to the reported byte). It is a bit surprising that you didn't check wiring integrity, but I get it, the engine blew up. I think the most likely cause is a partial, kohm short to ground or power (depending on the polarity of the sensor divider). Not sure how this could have caused anything you observed? Maybe it was just like that for years, an independent problem? It didn't seem like the engine acted particularly differently when you substituted your own resistance to bring it back to being correct so maybe just nobody noticed? Minor addendum: the "wrinkles" you see in the board's power planes are normal. That is a result of 1980s PCB manufacturing technology and it left the factory like that. I believe the way they used to do it was, solder plating was applied to traces before soldermask. Today soldermask is instead applied over bare copper (THEN they apply HASL, ENIG, etc. only to the exposed pins).

[@major__kong]

Is that big endian or little endian? Hahaha. I'm such an idiot on this stuff coming from a mechanical/ aero background. The closest I ever came to anything like you're describing is Wiresharking a Bluetooth connection between my phone and a radio called Beartooth similar to something called goTenna to reverse engineer what they were doing so I could bypass their SDK. Never got very far because I wasn't sure what I was looking at. Dang hex dumps. I had more hopes for the goTenna because I think it was using Bluetooth low energy, which I believe has to advertise certain things about the interface. And there are tools to look at that. This is now maybe the 3rd or 4th video I've seen where I'm wondering if the only way today's cars will become classics is if someone designs a new PCM using an Arduino, ESP 32, etc when the OEM versions become impossible to find. Heck, I think some PCMs could be replaced with analog circuits. The F-16's fly-by-wire system started off analog in the early 1970s and didn't become digital until the 1980s I think.

[@MrSleepProductionsInc]

They make aftermarket pcm’s. ‘MegaSquirt’ for example. I myself have never used one so not sure how they integrate with instrument panel. Seems like the ones I’ve seen people use a digital screen for the dash with maybe simulated gages.

[@jessicav2031]

@@major__kong It's a single byte, so there's no endian 😝 Yeah, we made custom electronics to talk to these on ALDL 8192bps. It's a bidirectional bus on a single wire, very simple circuit. (I also built my own "scan tool" that operates on the later Class 2 bus. It is pretty useful to be able to fake arbitrary messages from other modules!) In ALDL there is a hidden debug command which returns the value at one location in memory, and I looped that to do a full dump of the entire address space to back up our trucks. I think it would be really fun to emulate but TBI just kinda sucks. I think the early 2000s LS (before they added displacement on demand) is just a better engine. We've hacked that a bit too. Double the MPG right? And 150 more hp? And it doesn't sound like some super loud ancient machine?? 😅 Modern stuff is a lot harder since they have "security" to try to prevent you from messing with it. It sucks. Even early 2000s. Duplicating the electronics to run a modern engine has been done! I'm more worried about inspection rules, in that it is illegal to do so. It is illegal to use any part which is not certified for use. And where I live, there are inspections. Personally my reason to keep TBI going is that the vehicle has sentimental value, I don't drive the 8mpg monster very often anymore, so thankfully nothing gets very much wear.

[@major__kong]

@@jessicav2031 I told you I was an idiot on this stuff. I try not to let illegal or against the rules get in my way as long as it's safe and there's grey area. And there's a legal principle called "de minimis". Just don't be like the Diesel Brothers selling the stuff 🙂It's the only way to get things done where I work. As a program manager, they give me responsibility to get things done but not all of the authority to make it happen. The people who have the authority don't have ANY of the responsibility, and they will literally fight you with $1M of equipment and a $500K flight test range sitting idle. It's a recipe for disaster. So I do what I have to do like have a spare autopilot on hand that isn't technically airworthy for our particular tail number but is newer and more reliable and has the same power and logical interfaces and has flown on other models of aircraft similar to ours. The guy who was, for lack of a better word, my configuration manager including airworthiness blew a cork when I told him 3 years after the fact. But his boss was there when I said it and told him to take some pointers from me. Now, this was an unmanned aircraft, and we were flight testing in a godforsaken place called China Lake. If we crashed, no one was getting hurt. And potential loss of the hull was my decision to make not theirs. If you haven't figured it out yet, I work for the Dept of Defense, and this is how we roll unfortunately. It's also how we're going to lose the next war, but not if I can help it. BTW, no inspections where I live. It's like a regular episode of Just Rolled In. But our locals haven't learned the spray foam "trick" yet 🙂 I sometimes have lunch at this awesome gyro place. It happens to be next to an Autozone in a lower income part of town. The stuff that rolls into that place defies logic sometimes. I keep tools and a scan tool in my truck for my own emergencies, but sometimes I find myself helping or being asked for help.

[@travissheehan6082]

Wow this thing is crazy. Has to be an awkward situation for Ivan. I don’t the truck defeated Ivan; it defeated itself before Ivan could defeat it.

[@jimjaques4030]

Maybe I missed it, but I don't remember seeing you check the resistance of the temp sensor at the PCM connector with it unhooked from the PCM. Since both PCMs read about 40k high, maybe there are green crusties somewhere adding 40k resistance.

[@gorak9000]

There very likely is - there's a big connector that connects the engine harness to the other harness that goes inside to the PCM - it's known trouble spot. Some people even delete the connector entirely and solder the 2 harnesses together permanently to fix the problem!

[@jimjaques4030]

@gorak9000 too bad it really doesn't matter since the motor grenades. 😞

[@gorak9000]

@@jimjaques4030 I have a '95 with a 6.5 in it - it hasn't grenaded yet...

[@kerrylewis2581]

Sometimes, you have to know when it's time to give up. In this case, the engine made that decision for you. I'm happy to hear the owner understood.

[@kpfalconi]

I wonder if the ECT sensor had resistance in the wiring to the PCM causing the PCM to see elevated numbers. Sucks how it ended but very interesting case study.

[@nicholasanselmo2947]

I've seen this on a few 6.5 diesels. It's the pmd. If you have 4, all 4 can be bad. Remove all the jumper wires and plug it directly into the engine harness. I've had perfect looking extension harnesses that did this exact thing, removed and plugged that pmd into factory harness and ran perfect.

[@stevenwolfgang2744]

The engine temp inaccuracy is a mystery!

[@dwightelvey645]

Both computers, seeing the same! Both bad, unlikely. Still, there may be a common failure point. These measure ohms just like your digital meter does. It supplies a constant current and measures the voltage. Multiple failure points. Ground return, high resistance from the block? Possible that it uses a separate ground path for measurements. Voltage reference in PCM wrong? Something like an opened zener reference. PCM code failure? unlikely bot computers with the same problem. I'm going with something messing with the ground paths. Cleaning the end points is only part of the problem. I had a problem where constant oil or engine cleaner had turned the wiring insulation to mush. The wires shorted in the harness. The reference was at 12V instead of 5V. Fixed the wires to find the same 5V ref went to the pressure sensor in the tank. It was blown as well. Like I say, cleaning the end points of the ground wires isn't always what is need. One needs to look for cross connections or high resistance runs.

[@walterxplinge3867]

Not sure if there was another test which could have been done. Ivan checked the resistance at the sensor, but I don't remember seeing him test it at the PCM. Could be a wire from the sensor to the PCM was compromised, a touch of the green crusties somewhere in the harness could account for the PCM reading a higher resistance and thus a higher coolant temperature.

[@tschuuuls486]

​@@walterxplinge3867 he eliminated that issue, because according to that table a higher resistance would've resulted in a lower temperature reading.

[@walterxplinge3867]

@@tschuuuls486 as I missed that :( . The only thing I can take away is don't bring your vehicle to Plinges Garage if you want it fixed.

[@krzysztofstrojny1059]

also boost, with engine off there should be zero boost but here ECM was showing 14psi

[@davidgilpin5200]

Turbo diesel "malice in the combustion palace"! Blue is getting excited for this one... I wonder how many extra inspection ports were installed?

[@MarkS61]

I don't understand why you ended by talking about the high pressure pump. You showed clearly that the pcm was commanding the goofy duty cycles and the rpms were responding appropriately. There must be some bad signals going into the pcm. Maybe a wiring harness issue? Maybe scope more signals right at the pcm? Test the temperature sensor resistance at the pcm? The engine is toast and we'll never know. Man, I really feel for you, and us, for not getting the closure we have grown so accustomed to. Keep up the good work, Ivan. You are the GOAT!

[@TheOnespeedbiker]

Older ECMs are very hard to judge, whether it's the ECM or feedback from the PCM.. It sounded to me more like a diesel runaway, which is caused by excessive fuel (diesels engine speed is controlled by fuel not air). Since the ECM was replaced and the problem persisted, it was more likely a fuel problem.

[@truracer20]

What was being seen was the pcm attempting to keep fuel control with a bad injection pump.

[@tadawsonX]

@@TheOnespeedbiker And high RPM fuel cutoff worked. That likely would not be the case in a true runaway.

[@Stoney3K]

@@tadawsonX It wasn't a true runaway *yet* but it was probably sucking up oil causing the mixture to over-fuel. So even a hair of fuel would mean the RPMs spiked. Also, there were already some leaking fluids in the first video. That could have been diesel coming from the pump, if that were the case, the PCM could never control it in the first place.

[@smokeskull]

I had a customer call me with a 6.5 once and stated its running rough ever since he filled up. I told him he must have got gasoline instead of diesel and he swore up and down he put diesel in. I told him that the error may be with the station not having the right fuel in the ground be he woukdnt listen. When he was driving to the shop i could hear him coming a block away the motor was rattling so loud from the gasoline. I drained the tank and refilled with diesel but a week later it got towed baxk with a broken crankshaft

[@rogerstlaurent8704]

And i was saying to myself I wonder if there is gas mixed in with the diesel fuel ????? sure sounds like it

[@craigiefconcert6493]

Too bad they were so stubborn and also too cheap for a tow.

[@KStewart-th4sk]

LOL We had the opposite happen back when i worked on a railroad gang. Foreman sent a guy to fill up his truck (we had our own fuel in railroad car, both Diesel and Gas). Bit later the Foreman drives up with his Chevy gas truck sounding like diesel. Some goof on the Gang filled his truck up with diesel. He had to go put out flags before going to work (hell to pay if flags aren't up for the trains at your specified work block), so they did that, then came back and pumped the diesel out and changed the engine oil because it had diluted the oil as well. Gas in a diesel is pretty well guaranteed to destroy an injection pump, so i am surprised that 6.5 ran at all.

[@richb419]

Hi Ivan, not all vehicles are fixable, I think that truck was about to spin a bearing when you got it. you were the last resort of the owner. I feel that the problem was either the pump (a mechanic said in you last video that he changed many of them) or a turbo internal oil leak. Rich

[@kellyh66]

I think high idel command is not being disengage. When commanded on you touch throttle it goes to 1800, when you touch throttle again it is adding another 1800 which makes 3600. When you hit the rev limiter it disengages. When it is engaged that second throttle touch is engaging it again instead of returning to idle.

[@petrnemecek4379]

I think the 1800 rpm is some king of last resort strategy when the ECU is sure someting is wrong.

[@jtjones4727]

Wow this was a very interesting case. I don't know a lot about diesels anyway, but I was very curious to see the conclusion to this one. It does seem like there was an issue with the solenoid in the pump, causing it to overfuel and runaway. Well you can't win them all.

[@kellyh66]

Baked into software is high idle mode for pto operation. I belive that was 1800 rpm. I would try and turn it off and on. I don't remember the procedure.

[@tylermacconnell217]

Sometimes high idle is automatic a couple of minutes after a cold start. However, with the ECT reporting nearly warmed up, not sure that is the case. PTO mode is possible though.

[@jeffco908]

On the 6.5l the PCM has 2 terminals that PTO(high idle) circuits can be added to. Grounding 1 of them gave you an idle speed of 1070 rpm the other one when grounded would give an idle speed of 1360 rpm. I remember doing these many years ago with a 3 position toggle switch. Not sure what might happen if you grounded both. Maybe could get a 3rd speed close to 1800rpm? But still would not explain hitting the rev limiter.

[@aranhaydar9195]

It happens Ivan, But I'll say one thing, i love the way you always want to prove your point, so do i. But when it comes to that point where you can't prove it, just dig into it, look at the pcm & look at the hp pump. The picoscope is a great tool, but it has its limitations, don't overuse it 🙃 thanks for your efforts, most of what i know comes from your videos.

[@deweydodo6691]

Glad there are not many of these kind of endings. Saw a Buick come in a shop for an oil change with a knock. It left with an even worse sound. Wondered if the owner thought it was worth paying for fresh oil?

[@pootthatbak2578]

You gave us a video..we are all happy.😊 i do feel bad for the owner. My sympathy to the family😢

[@retireditguy9493]

This problem seemed to have all the indication of electrical noise. I have been burned by this. It would have been good if you put a scope between the alternator output and the battery negative and check for A/C ripple of more than about a half a volt. The fact that you had to use a jump pack is also a potential symptom of a diode that is either bad or on the way out.

[@garysurovec]

Even though yes, the engine has its issues. The electrical conditions were screaming a bad or loose ground somewhere. The pcm seems like it had no reference to either ground or maybe another feed from somewhere. Always start with power and grounds, toss the scan tools for a bit.

[@jamesfitzgerald2361]

Engines dont fail overnight the rod problem has been around for a.while you just happened to be on the end of its days.Take care Ivan.

[@Djriggs-f8q]

Had same scenario happen on earlier 65 diesel truck. The original PCM that was relocated. With a aftermarket one caused the PCM to get spiked and the cause their wreck signals. Had to replace ECM and p MD. To fix the problem. But after that it developed the rod knock from an overeving😅

[@10100rsn]

A dually to tow a dually. That is a poetic ending.

[@bobwilson758]

I heard that nasty engine terminal sound …. She is done ! ✅ 😮😢

[@dougkubash8673]

Damn it! In part1 you seen the oil leak. I think it was pretty fatal when he brought it to you. I hope it works out for the customer with the engine replacement!

[@greghoen6998]

It may have a broken crank those blocks they did some things to improve piston cooling that made the main webs crack as well as the harmonic balancers go bad and the crank gets broken

[@bradfaught1695]

I just scoured alldata trying to see what i find on the resistor built into the fuel driver module. Couldnt find anything there but found the 9 different resitor values and that it takes 50 key cycles to check. So guy probably relocates the fpdm and its fine until 50 key cycles until it checks that resistor value. I like the direction you were going with the decade box.

[@KarlGillcrist]

I know with your determination you would have got to the root cause of what looked like multiple issues...coolant temp??...rpm control and I also don't understand why boost psi was at 14 with the engine off...sadly the detonation timer was set before it came to your shop...In the end you learned new ways to work with your tools so not all is lost ..keep up the good work .....Karl from eastern Canada

[@tam1381]

Hey Ivan look on the bright side. No parts required.....

[@robertsmith2956]

Well one part was required. the PCM to eliminate that as the problem.

[@major__kong]

I guy I knew would run his aircraft engine hard like probably red lining it to do high speed passes. One day I'm hanging with my IA (inspection authority for aircraft) and we get a call that he was over in Illinois on a country road. He spun a bearing on takeoff and Uncle Rodney came knocking. Punched a hole in the case and the engine cowl. Somehow he managed to find the only road that didn't have power lines running down the length.

[@michaeltichonuk2176]

The ones that keep me awake a night...feel for ya, Ivan.

[@chrisandrew3388]

enrichment sol on pump is sticking i think had same thing reving up and down hope this helps

[@BroadcastBuddy]

Why wasn't the transmission control feedback looked into? That was a rock solid indicator. Rpm s stabilized with it in gear and continued after returning to park.

[@truracer20]

That is the pcm trying to keep fuel control over a bad injection pump. Diagnosing an over reving diesel by allowing it to over rev is akin to diagnosing no oil pressure with the engine running. In this case the engine was doomed long before it came to you. This is why not red lining a diesel engine is important. The mass that has to change direction is huge and the change of direction happens not only at the top of the stroke but also at the bottom of the stroke where there is absolutely no load to control it.

[@fredweather3366]

Nicely said. That's a Great learning comment!

[@davidfleishman2275]

I worked at a GMC dealer 1977-1982.With the 350 Olds diesel.At the end of the first year of working on them the shop had a dozen rebuilt injection pumps in stock. We would go, if the engine was doing so and so put a pump in it.

[@BesprovolkiSvias]

I nominate this beautiful FILM for "Best Parts Cannon" award. In this case, it achieved its usual results. The only problem with this drama is that all Goode Ole American films end on a good note. This one is super rare exception.

[@keysautorepair6038]

The surging rpm used to happen when the battery was disconnected in the gm would take a few days before it quit doing it!

[@neilcook4710]

As much as i love "diagnosis from the driver seat" or data based diagnostics as you put it, sometimes we get caught up in the fine details and forget super-basic mechanical health of the engine. I've done it. We've all done it. Not sure if volumetric efficiency data would help in this situation before condemning the brain.

[@liquidhandwash]

I've had a similar issue on a different vehicle, A Peugeot 406 diesel with an electronic pump, (Not a common rail) would randomly rev up by itself and surge, but it was not really repeatable. It was my own car and I chased the fault down for weeks, it also had no codes on the PCM. It turned out to be a bad alternator. Only found the fault after the alternator completely failed and I repaired it. The whole time I was watching the video I was screaming at the screen "Disconnect the alternator!" I did notice the truck had a NAPA "quality" replacement.

[@patriot2164]

Bummer ! Thought we were gonna see what was causing this ! Damn feel bad for you both , the owner must be bummed ! Shame it looked like the truck was well taken care of almost 30 yrs old

[@rambleon2838]

Convert it to 12V Cummins or drop in an AM General GEP Optimizer 6500 long block with a Quadstar tuning injection pump. Quadstar Tuning is in Butler, PA and specialize in the 6.5. That truck has no rust issues and is worth saving.

[@g0fvt]

A very embarrassing situation, as someone that has spent most of my life fixing things I feel your pain. Having seen your videos on this vehicle I am wondering if it might be fuel contamination? As for the engine temperature issue, is this a C/F problem the figures looked like it. A one point you mentiona resistor that should read 113 but was reading 253.... 113c is 235f.... so figures are in the right ballpark... if that is the case.

[@lukejaffe2533]

Pump mounted driver on the injection pump is very common failure on these and causes these symptoms

[@brycelund7155]

It had been replaced 4 times.

[@lukejaffe2533]

@@brycelund7155 I went through 6 of them before I finally got a good one

[@rambleon2838]

The symptoms for a failed PMD are intermittent or sudden stalling and hard start on a toasty engine. None of those were present.

[@robertgraham1626]

I just went through that on my 983500 65 turbo I went back through and cleaned and re-secured all the grounds everywhere little bit of moisture developed under the dash I replace the TPS as it had an odd spot jump and the brake switch I replaced it because when my foot was on the brake I couldn't rev the engine thing runs great and that rattle that annoying rattle I took the heat shield off the exhaust this followed a trip back from the job and it bent a push rod replaced it and The Rocker assembly all is well also put a new OEM turbo on with a few slight modifications things are working way better now plus the resistor

[@djambrosia]

I'm still pondering the odd coolant temp reading.

[@bernardaflores1720]

Me too

[@gorak9000]

There's a known issue with the connector between the main engine harness and the harness that goes inside to the PCM. Probably could've been fixed with a couple shots of deoxit and unplugging and re plugging the connector a few times. And checking that all the grounds are good too. The grounds going bad is another known issue. Well, at least before the rod left the party...

[@djambrosia]

It seemed likely a wiring issue as that would explain the ohm disparity.

[@rogerstlaurent8704]

Sounds like there was gas mixed with diesel fuel not a PCM issue

[@leedress2187]

I was thinking possibly resistance in the wires to the temp unit. Maybe that why the temp was so far off.

[@dbechth]

A bad injection pump doesn't explain why the coolant temp is reading incorrectly even with a decade box. In order for the ECU to measure resistance it has to use some sort of internal reference voltage. Sometimes that internal reference voltage is used externally to power other sensors. Since both ECUs exhibited the same problem it makes sense that something external to the ECU is affecting the ECUs ability to function normally.