You replaced my starter now i have a misfire - 2003 Lexus SC430

[@DTEAuto]

Awesome presentation! Definitely worth sharing and shows the power of the scope to be able to capture an undeniable piece of information especially when intermittent. It would be difficult to make an exact call just like you said. The only thing that is true and known, is the fact that there is a loss of compression pressure and a loss of the "blip hump" at 360 mark. Engine mechanical issue found. 👍👍 The blip point at 360, when I try to make sense of the waveforms, comes from when the exhaust valve closes (before 360 TDC) while still on the exhaust stroke. The only way to "make" positive pressure (the rise in the waveform, i.e. "blip") at that point is for the piston to still be traveling upward and all valves to be closed, the the drop is from the pistons direction of travel change (after rolling past 360). I will often see this "blip" be present on vehicles with variable cam timing on cold starts and then as it idles and warms up the "blip" slowly goes away as the computer controls the exhaust cam. That helps confirm the source of the pressure rise/blip. The loss of the compression, and the loss of the "blip" can certainly be caused by the "loss of valvetrain control," like a lifter as you mentioned. One other possibility could be from valve sealing issues as you also mentioned I believe when talking about the valve spinning in its seat. If you think about it, the low compression point was when both valves should be closed and piston at TDC.....the very next point that the piston comes up to TDC is at 360..... AND when both valves "should" be closed (because the exh valve closed in the other cycles and built positive pressure creating the blip)..... BUT, both times those two points happened there was pressure losses occurring as you clearly captured and it happened all in the same 4 stroke cycle. Also one last thing to note....from compression TDC through 360 TDC the intake valve should be seated and sealed on the seat. I just wanted to mentioned some of those points that I was thinking about as I watched the video, I hope it makes some sense as to what I tried to explain. Thanks again for the great content.

[@weldingjunkie]

I know you’re a big scope user/fan too. I think you are spot on with that. Some of the vvt blips are much more pronounced. With the lack of compression and valve train operation that makes sense what you are saying. You and Mario should do a joint diag that would be fun to watch

[@nowayjose596]

My money would be on a leaking intake valve for the reasons you mentioned - it's the only valve that remains in (closed) position from the top of the compression peak to the top of that 360 blip (or lack thereof during the misfire) so it's leaking out pressure in both instances. I can't remember if it was Bernie Thompson or John Thornton who mentioned it, but I remember one of them noting that the beauty of an in-cylinder running compression test using a scope was the ability to catch something like an intermittently non-seating valve specifically. So my guess is there's one very small section on the valve face that interacts with one very small section on the seat to cause the issue, but bc the valve is constantly rotating 99% of the time it's fine bc they don't line up but when they do, boom, misfire.

[@weldingjunkie]

@@nowayjose596 Bernie and he’s amazing. I’m an ATS distributor so I get to work with them. They are an amazing talented group.

[@DTEAuto]

@@weldingjunkie I'd be open for it

[@IamReadyToRock]

En español my friend 😁

[@1supratech]

My guess. When the other shop replaced the starter, they did not cover the intake ports on the head when they pulled the upper plenum off. Something dropped inside the cylinder. The noise we are hearing could possibly be the debris floating around the cylinder hitting the cylinder head. The debris is probably getting stuck under the valve causing the misfire.

[@DA9enthusiast]

That’s what I was thinking too

[@salsinger9985]

they can just borscope the cylinder !

[@Andy-ms9vi]

You have a good shop that's willing to charge enough diag to have a tech go in cyl. The customer is definitely getting a second opinion, next time you see this car it will have new plugs, coils and injectors in it and the same issue.

[@djosbun]

Spot on, Andy.

[@johnriley7053]

100% agree Andy.... Ahh but, you also have to have a customer willing to pay the premium.

[@Andy-ms9vi]

@@johnriley7053 Yeah, but maybe customers have been trained by shops not to value diagnostics by shops charging too little or nothing at all. Customers don't seem to have a problem throwing thousands of dollars in parts at a car.

[@fascistpedant758]

I've used a compression gage with the Schrader valve removed a few times. It does the job if you're only interested in peak compression. If you can install a timing light synchronized to TDC, to strobe the gage, it makes it easier to focus. A good quality oil change and maybe an additive to break up carbon deposits could help. Diesel oils used to be good at dissipating carbon.

[@kdawson5]

Just had a similar issue in a 3.6 Chrysler. Had an intermittent leak on the intake side caused by a sticking lifter. But I was lucky enough to catch it with the borescope turning the motor by hand. One valve was closing late intermittently. I would have caught it sooner if I had a pressure transducer. Time to get one!

[@alexblok883]

Good job, partner, good thorough step-by-step diag… I like what you did here..

[@mikechiodetti4482]

Your right about the dislaimer. You did a very good diagnose. Maybe monitoring the intake vacuum would give you more information about that intake valve. I was also thinking how many miles does the vehicle have on it, and what about oil pressure? Is the engine low on oil? If the engine is low on oil and/or has had "extended" oil changes, that can add to the problem. Good video Mario!

[@samwiggins5349]

Always great to see a Super Mario video. 😀

[@nickayivor8432]

WISE,Super Mario Diagnostics 👍 From Nick Ayivor from London England UK 🇬🇧 ⏰️ 17:40pm

[@GarthGoldberg]

SC430 has solid lifters, bucket style with shims. Probably clearances never checked. There may be a tight exhaust valve on that cylinder.

[@speedy_pit_stop]

Thanks for making this video. I am not convinced the starter replacement has nothing to do with the misfire. There "could be" something in the intake port... maybe? It can of course be a sticky valve or lifter, we don't know, but that's what makes it fun to watch and think about. That ticking noise though... would love to know what cylinder/valve it came from.

[@justindavis5146]

Great video, I dont understand why also shop would take the heat for a vehicle that came in for a no start fix that issue and then it starts to misfire right after. When I fix a car especially if multiple parts are moved or removed then recheck if anything was unplugged. Its the classic “ever since you comment”

[@pl5882]

296K mi on my 430. Great vid!

[@sonsautomotive]

i have a topdon elite that is 6 months old..bought it thru aeswave..2 year warranty....the dongle is erratic and topdon says there is nothing they will do to fix it...i am just trying to warn other mechanics about topdon...great video!!!

[@SuperMarioDiagnostics]

You bought it through aeswave. Have you reached out to them about it? Shoot me an email at [e-mail]

[@1MiketheMechanic]

Do a factory reset. Had a software corruption on mine and it fixed it.

[@exmotorsports]

Great Stuff as always Bro. Ya I know, its been awhile with any comments. However, I'm always watching. 😉 Cheers

[@rodvan-zeller6360]

At 19:58, intake vacuum wave form on the scope will show intake valve issue.

[@coreyjones7372]

Thanks for sharing your knowledge with all of us. Wish I had alot more diagnostic knowledge. Thank you

[@jakemartin4305]

I wanna see history of oil changes for that car 😂😂 great find and would love to see follow up if possible

[@JoelAutomotiveInaction]

Thanks mario for this super diagnosis? Recently I did a diagnosis on a lexus Rx 300 same set up than that vehicle , They do not have hydraulic lifters how ever they have adjustable shims . On my case (I posted that on my channels as case study análisis live event the same way we did when we invited you) surprisley in my case I had compresión with no exh valve lash at all.

[@gmtech2012]

Bernie's equipment would be able to narrow this down further because there would be an intake and exhaust transducer installed.

[@weldingjunkie]

Good stuff Mario I think you are right about the lifter

[@devttyUSB0]

Ever since i've watched your video .... ;-)) Great diag, thanks for the detailed walkthrough!

[@jharrison6557]

I would add a pulse sensor in the intake and exhaust and analyze those readings when the misfire occurs...pulse sensors arent always ideal with a running engine but you may be able to pick something out that could help your diagnosis

[@Discretesignals]

Awesome diag! Could it be possible that when the starter was replaced something fell down the intake and it is causing an issue with the valve to not seat? We had a firebird in the shop that the intake was removed and a piece wire harness plastic clip fell down the runner. It was to large to go through the open valve, but it caused the valve to not seat. Would have been interesting if you sent a borescope down there with the valves open to see if anything looked peculiar.

[@aswinpak7767]

Nice content Mario 👌🏻. Love to see your videos. I was thinking, maybe it’s possible to see some discrepancy in the waveform when you hook up a pulse sensor to the intake? It’s not as good as the WPS but you might get lucky.

[@kasapis6]

Great work thanks for sharing

[@gilbertgarcia1575]

Bernie Thompson would say " watch for high lows high lows".

[@mrblonde2013]

Interesting, the old"ever since you fixed X on my car my wife is pregnant" are always difficult and frustrating. I probably would have put a pulse sensor in the exhaust with an ignition sync to verify which cylinder is missing, i do not trust the scantool for that, especially on something this old. Followed by ignition and injection monitoring with a scope at the relevant cylinder, then incylinder with a pulse sensor on the intake. That would yield enough information to make a decision i think. I thoroughly enjoy these cases, i always learn something from them. Thank you.

[@djmobileautoservices]

Long time no seen buddy. Thanks for sharing

[@ThunderbirdRocket]

Nice job 👍🏼 ! Super coaching !! Thanks

[@SkyFighter123]

Definitely a mechanical issue, if you wanted to go deeper I think a couple of pulse sensors on the intake & exhaust would have caught where it was leaking. Of course, you still have the issue of if it's a valve or a lifter, so I get the need to not go any further since if you're in there, you might aswell change them all. I think some guys who are really good at intake and exhaust waveforms can tell but that's beyond me lol. Great & efficient diag Mario!

[@clublength724]

Masking is a powerful tool for identifying and isolating anomalies in a signal, such as glitches, and it can be particularly useful when diagnosing intermittent faults in vehicle systems.

[@jharrison6557]

What is masking?

[@advancedleveldiagnostics]

Yup a Starter will definitely cause that🤣🤣. Great job!

[@rjeromej8149]

This is why I do 2 scans prior to touching any vehicle, the Global OBDII is always first, I/M Readiness status is documented, mode 6 data and documenting any misfire history, then the VIN Specific.

[@cbarkwell1000]

You are Smart , you'll doing the right thing. Ex Smog/Repair Tech. Southern California

[@daviddasilva4897]

Great diag marii,i like your tric to find intermitent missfire

[@OneLegged-honda-mechanic]

Great video! My bet would have been a broken spring. The cam acts directly on buckets with this design, so I guess not much it could be. Unless something is messed up with the guide.

[@djosbun]

Super video, Mario!

[@Properly-Gapped]

Another great video!

[@olegtimercan]

i can hear that hydraulic valve lifter clicking )))))

[@Bizija123]

Could be an occasional sticking or weak valve spring?

[@ls6097]

Super interesting....if hydraulic lifters, perhaps a blockage in one of those small orifices that is small enough to be overcome by builtup oil pressure behind the blockage pushing by it and then the blockage slams shut momentarily like a screendoor flapping in the wind...creating your momentary misfire.

[@sheerwillsurvival2064]

Great diag. Hope you get to tear down. And make part 2

[@rodvan-zeller6360]

At 22:22 since this engine does not use hydraulic lifters, my first suspicion is an intake valve sticking from excessive carbon build up, my next test would be vacuum wave for with scope, if anomaly present, my next step would be ani induction cleaning ass part of the diagnostic process.

[@rodvan-zeller6360]

OOPs form not for and as not ass LOL

[@LuisHernandez-vc8yc]

It happens to me in a 7.3 Ford f250 gas. Intake lifter and camshaft

[@Jose-pp7sg]

Good Mario 👍👍👍👍👍

[@pauldavis8716]

I believe this car had this problem before and also since it doesn't really caused real drivability issues, I say let them drive the until the misfire gets more consistent so it can be diagnosed properly

[@POKOYOR]

Is the starter not in the v of the motor did the intake manifold get removed just saying small chance this could have amplified the condition

[@rodvan-zeller6360]

If you still have that car available, would love to see intake vacuum waveform as it misfires. I remember a 1988 Acura integra with the exact same symptom getting fixed with an induction cleaning

[@RATCHETMAN1001]

u have hit the nail on the head. i think i would pass this veh to some other shop. if u fix it then they will come back and say some thing else is happening and its ur fault. thankfully they left.whew. we no how this goes. i think lifter for intake, does it have roller lifters cause one of the one u showed look like a downward curve u shaped compression over several events before it recovered. reminds me of the roller bearing issue.

[@JorgeTorres-is7bv]

Btw, hitting the “graph” button for the PIDs is much easier to see all of the misfire counter in one view. So you dont have to keep scrolling up and down. :)

[@IamReadyToRock]

Descargo de responsabilidad... como tiene que ser, ya que hay bastantes clientes que aseguran que su auto estaba funcionando bien 👍🏾👍🏾👍🏾

[@fredsalter1915]

Excellent vid!

[@vipercrazy-9]

UZ engines do not have hydraulic lifters, they are dual cam with shimless buckets. Measure TDC on cyl 6 using a piece of coat hanger then do a leak down test. Drive the vehicle while logging the misfire and it may misfire more at idle after fully heat soaking.

[@rodvan-zeller6360]

At 25:51, I do a full scan including dedicated and global on every car before working on it for documentation purposes.

[@rodvan-zeller6360]

At 9:50, I am looking at the car through the window as I am eating lunch, LOL

[@cjmazdatech]

Would a pulse sensor in the intake and/or exhaust give any useful information? If you couldn't go in cylinder.

[@richardcranium5839]

i'm thinking scored valve guide. intake pulse would show which valve.

[@jackiemay9471]

how long was it left before having a starter it would have been nice to have the 720lines for tdc bdc lack of oil servicing gumed up lifter better when hot

[@timbo19751975]

Got a nasty lifter tick - any wear in the valve train ??

[@rodvan-zeller6360]

Great video

[@Nakkilauta]

Great comments also. I was thinking even if the engine had hydraulic lifters, wouldn't issues with them cause the valves open too little instead of staying too open and causing compression loss?

[@SuperMarioDiagnostics]

If they were collapsing yes. Not if they were binding

[@Nakkilauta]

@@SuperMarioDiagnostics True, didn't think they could bind. Anyway in this case I'm thinking it could be possible maybe some crap got into number 6 intake port while replacing the starter and when the valve rotates to exact correct position then the valve leaks.

[@Nakkilauta]

@@SuperMarioDiagnostics #6 compared to known good cylinder waveform would be interesting to see if there is any difference.

[@SuperMarioDiagnostics]

Would make sense. No further action was approved unfortunately

[@tonyfremont]

That exhaust back pressure looks to be a sizeable percentage of the 80 psi spikes, so im guessing over 5 psi, maybe 10psi of back pressure?

[@oldhotcars]

Would a slightly worn valve guide cause an issue like this? Or would it present more consistently?

[@leftyspinn]

What leads are you using for the micsig? I find the micsig leads very short and the ground cable also short and lots of times cant reach battery negative. Had to go back to my hantek leads

[@chrisi1909]

Send the Waveform to B.Steckler - he can take a look and make a Video for it in Wrench Tales

[@bradjames3555]

maybe a pulse sensor in the intake would show the anomalie leaking back into the intake rather than the exhaust..

[@HUBONEN]

Would you pinpoint that with pulse sensor on intake? If intake valve leaks would you see higher pressure peak in intake when this occurs?

[@user-ky7ty3ie1x]

Hi what model miscig you used please

[@rodvan-zeller6360]

At 19:28, I don't think those engines have hydraulic lifters.

[@SuperMarioDiagnostics]

@@rodvan-zeller6360 you are correct. valve lash is still in play here though

[@fascistpedant758]

@@SuperMarioDiagnostics It's easier to just call them lifters than to say "hydraulic valve lash adjusters" every time.

[@steevo630]

Could you have used a delta sensor in the intake to prove it out? Obvioisly would have required you to get it to act up again,

[@htownblue11]

I’d have to believe the valve rotates to a specific spot which carbon build up probably allows a small amount of leakage??? Just my theory 18:13 into the video.

[@alinduta5398]

when compresion tower is vertical is not leaking compresion is not enough air going in cilindre

[@thekeeneygarage]

solid

[@lorayhinny8956]

So much pressure in the exhaust valve. I think it's a broken spring or camshaft issue

[@ThatDIYguy862]

customer took the vehicle cuz they were hoping the shop would eat the price and fix it and turned the other way when they found out shop won’t cover it

[@2491kridge]

I guess the only other non intrusive test I could think of would be a amp clamp relative compression test but with how intermittent this was I highly doubt it would show anything useful. Ivan at PHAD has shown some really in depth analysis of breaking down pressure transducer data like you were showing here and pinpointing exactly what every little detail shows you about what’s going on in the engine

[@rodvan-zeller6360]

At 24:09 it is called the "eversincesyndrome"

[@chadgardee1496]

I would have just stuck my ear on valve and I would have diagnosed it 😂 just joking

[@rashidahmed4647]

Broblem is in the intak valve open, maybe something loses. back to oss when you will get solution , we still learn about oscilloscope.

[@mistsmogguru8378]

We replaced a door mirror. The clutch slipping only happened after that ! Explain the logic in that !

[@scotts4125]

Easy to explain from a customer point of view. We call that a "since you" :) There is 0 logic nor do they care. They just want someone else to pay for it.

[@AnthonyRusso-ln3ee]

If you believe it to be an intake lifter, couldn't you use a vacuum transducer. Wait for the compression loss and compare to see if the map increases?

[@joachimjohan1215]

wuuuuuuuuuuuuuuuuuuwuoo

[@E39M5SPEED]

Bro. Pull the plug. Do leakdown. Takes 30 minutes. It’s not a lifter. Those 1UR engines are bulletproof. Maaaaaybee a leaky headgasket. Mayyybeeeee. No way in hell it’s a lifter.

[@1MiketheMechanic]

One of the problems with working on a vehicle older than 15 years old.

[@jimyep9971]

Yes but avg joe cant afford price of newer cars! or new.

[@PaulCTownsend]

Try higher or lower viscosity engine oil just for a test on the lifter.

[@Foolish-diag]

Vaccum nm😅

[@janpur1417]

THE MISSING HUMP YOU SHOW AT THE END OF THE EXHAUST STROKE CAN BE IT IS NOT CLOSING AS IT SHOULD? A DAMAGED SEAT ON EXHAUST ON ONE SPECIFIC LOCATION?

[@danishzd]

Why waste time on the diagnosis, why not replace coils, plugs then injectors and then the computer like normal shops.

[@anthonymarsala5116]

I think you guys are reading way deeper into it than needed. technology is good, but takes you down the rabbit hole making it more complicated. I say get back to basics!

[@SuperMarioDiagnostics]

@@anthonymarsala5116 and basics will reveal what?

[@rodvan-zeller6360]

@@SuperMarioDiagnostics The basics will reveal that you have a misfire. LOL

[@SuperMarioDiagnostics]

@@rodvan-zeller6360 LOL

[@JoelAutomotiveInaction]

This is basic what Mario proved out !!compression issues that would never never catch on the trusty compresión gauge. this type of diagnosis is the proved of analog gauges weak points . Still is testing for the basics in different tools approachees that will definitely show the fault that occurring when it's wants , intermittent. I am old schools tech , that incorporated this techniques to my tool box many years ago , maked the difference on the field proved !

[@jordysandino6577]

Bonito video primo . Gracias por compartir. También a dteauto (sadel ) por el comentario eso es de mucha ayuda para nosotros primos