Pico Scope: Measuring Fuel Injector Pressure Drop

In this video I take you through the process I use to check fuel injectors on a car that is setting lean codes. After eliminating all possible variables and determining it is a fuel delivery issue we need a way to prove it. Let's have a look. -Enjoy!
If an SMA Video has helped you out please consider giving using "Patreon" to help support us. The videos take real time to create and pull us away from real work that pays our bills. CLICK HERE: / southmainauto
CHECK OUT OUR "SMA SWAG" STORE! Go on Teespring and get your very own SMA merch!
teespring.com/stores/the-sma-...
If you don't like Patreon feel free to use the "PayPal Me" link: www.paypal.me/SouthMainAuto
The South Main Auto Amazon Store:
www.amazon.com/shop/southmain...
AES Wave Automotive Diagnostic Tools: www.aeswave.com/cart.php?m=af...
Thank you for all the continuing support!
--Eric & Vanessa O.
Feel like sending some swag to SMA because you love the videos but don't know where to send it?
Just ship it here:
South Main Auto Repair
47 S. Main St
PO Box 471
Avoca, NY 14809
Disclaimer:
Due to factors beyond the control of South Main Auto Repair, it cannot guarantee against unauthorized modifications of this information, or improper use of this information. South Main Auto Repair assumes no liability for property damage or injury incurred as a result of any of the information contained in this video. South Main Auto Repair recommends safe practices when working with power tools, automotive lifts, lifting tools, jack stands, electrical equipment, blunt instruments, chemicals, lubricants, or any other tools or equipment seen or implied in this video. Due to factors beyond the control of South Main Auto Repair, no information contained in this video shall create any express or implied warranty or guarantee of any particular result. Any injury, damage or loss that may result from improper use of these tools, equipment, or the information contained.

[@SouthMainAuto]

Before you give all of the thumbs down and negative comments because I am using modern technology to repair a car keep in mind I run a professional repair shop and I am not a DIY'er. Thanks for considering that first. -Enjoy!

[@deepsquat600]

that modern technology uff is weird LOL ..same stuff that makes the car run>?????

[@curtis4812]

You have to make money first, lol. KZbin adsense can't be paying much more than a cup of coffee a day.

[@williamdenommee4128]

A car is never to old to use modern technology :D

[@markh.6687]

"Uh oh! We got a bad-ass over here!" - Internet meme. Eric O. is great for sharing so much time, effort and knowledge with those who don't have shops and all the gear. Seriously, anybody downvoting for those reasons is a real idiot who should be chastised and ignored. (And before anyone says it....I AM serious, and don't call me Shirley!).

[@markh.6687]

@@deepsquat600 what manner of sorcery is this?? :)

[@caravan1ify]

easier than a windshield washer motor problem!!

[@markh.6687]

Yeah, but those Blinker Fluid problems are even worse. My scan tool reads "TILT!".

[@justinballard7242]

Too soon fella haha

[@FredTheLutinoCocatiel]

@@markh.6687 you must have a scam tool

[@keithmenges79]

Now THAT'S hilarious!

[@edwardsilva895]

Ouch!

[@baxrok2.]

Well, I'm a DIY'er and I run my $200 2 channel Picoscope on a $100 used laptop. It does basically the same thing that yours does. Can't afford that? Well, I also have a $60 single channel scope that can grab those same waveforms! If DIY'ers aren't willing to spend a few hundred dollars for top notch tools to save themselves thousands of dollars in maintenance costs, tough $hit! Get over it people. Love that Pico. Thanks Dr. O!

[@charlesdavis9755]

Your modern diagnostic technology stops you from being a parts cannon. People and customers aught to appreciate that. Keep up the good work.

[@markorlando4817]

After you fit a set of injectors, do the test again and we’ll have a known good. PS love your work.

[@howardlland13]

Curious, what did the customer want done, and , the results. Thanks for all the great videos and the comic relief.👍👍🤣🤣

[@joeventimiglia6326]

Is there a part 2 to this video?

[@tripshobbies2810]

Whenever I fall asleep with youtube playing this channel always lands up playing eventually and the sound of an impact wrench wakes me up :)

[@michaeltrue1143]

I'm a full time mechanic also but I learn so much from your videos I didnt go to school. I learned a lot from my dad growing up self taught on newer cars. Thanks for the videos been a long time subscriber!

[@miceinoz1181]

Yep, seeing how you use modern technology to identify faults is the very reason I watch your channel. Keep up the good work.

[@edthompsom9368]

SMA channel is my crack....I get so much out of watching videos, even on cars I don't own but the video quality and narrative is always top shelf.

[@flagmichael]

I spent 48 years troubleshooting electronic equipment, including about 40 years on computer controlled equipment, before I retired. Seeing solid troubleshooting like this is like Springtime in the Rockies.

[@bdiscreet69]

Just when I was getting bored of KZbin, another awesome SMA video appears 🙂

[@crisprtalk6963]

Whenever I get bored of KZbin I watch a couple trucks smash into the 11-8 bridge. Give it a try.

[@lackeydehackey405]

@@crisprtalk6963 I watch Foxes and Fossils when that happens and wait for Mrs. O to post the Big Guy.

[@johnhubbard3399]

@@lackeydehackey405 Damn good group I lovem too.

[@billcullen2480]

@@crisprtalk6963 It now 11-8+8 and seen them all

[@JoesAutoElectric]

Love that test Eric. I have fixed many cars doing this over the years. Before the transducer, using a traditional fuel gauge of course. Rule of thumb was they should all drop the same. 1 psi is broke. Doing this test using a transducer is so much nicer as we can save the data we collect and prove the failure to the customer right on the screen. Great call on all six for that van. Way too much mileage to play with one or two.

[@rafaelmarin1963]

Are OEM injectors the only good option, or do you know of other off the shelf (Napa, O'Reilly ect.) that can be substituted?.

[@flagmichael]

@@rafaelmarin1963 I have been bitten by aftermarket injectors. I bought a set of Pythons many years ago for our 1985 Volvo. I could hardly get the engine to run. It turned out the Pythons fit just fine but were unprepared to deal with the ballast resistors in line with each injector in the Volvo. (BTW - I also say it as a good call to recommend replacing all injectors. They all had about 200K miles on them and two out of six were wonky at this point.)

[@jamesmccartney5731]

Here's my take on SMA, if Eric can't fix it,it ain't fixable!

[@FredTheLutinoCocatiel]

You could always try chrisfix

[@VWWRENCHIE]

SMA. SUPER MAN AUTOMOTIVE

[@MrTexasDan]

Unless the problem is a washer motor :-)

[@markchidester6239]

Thats kinda like me, If I can't loose it, it can't be lost. Think I own 75 tape measures. Probably a few more that I haven't found yet

[@suttoncoldfield9318]

@@MrTexasDan We don't talk about those around here

[@flatnose7314]

Just finished a "day in the life" and SMA pops up. Gonna be a good day.

[@wdhewson]

I do respect a skillful and intelligent diagnosis Thanks.

[@Zib187]

This video was almost too much for my OCD to handle. Those leaves on the cowl were driving me nuts. 🤯

[@VWWRENCHIE]

Just wait till the snow and ice comes..lol ..

[@markh.6687]

"The leaves on the cowl in Autumn wound my heart with a monotonous languor" -- Verlain poem, paraphrased.

[@flagmichael]

For some reason, when you mentioned it I imagined a snake coiled up on the cowl and Mr. O unconcernedly checking the injector drop.

[@raymondbeechner5749]

Try owning that piece of crap, the leaves are the least of my Worries. 🤬🤬🤬

[@Zib187]

@@raymondbeechner5749 Had a 2007 & had no issues with it while we had it then it got stolen.

[@johnlee8231]

I appreciate the techno wizardry demo and explanation of how you got there

[@gwiz1100]

have watched quite a few of your video's, some of the best i have ever seen if i lived in NY you would be working on my cars

[@billyyoder8171]

Thank you Dr. O. Good job. Have a blessed and safe week to you and your family.

[@robmut1357]

Great video. As always, I admire your logical reasoned approach to diagnosing. It inspires me. 👍😁

[@J8MORS]

This is why I subscribe. These are great videos, I like watching other individuals use the tools to perform great diagnostics.

[@kastooMcFry]

That pico scope looks like an incredible tool to me. A really interesting way of figuring out what the problem is! Thanks, Eric!

[@jimgetz2898]

I really like this, you have car wisdom. Thank the Lord. I thought my friend and mechanic was the best and most honest person in the Business. Good to see others up there as well. Stay the. course

[@rrmech11]

Excellent Diag. Dr. 0 Reminded me when I had to learn the drop test In my 2007 indiana emissions certification. Your the BEST 👍👍

[@ColoradoMoe]

Absolute genius! I normally pull the injectors and run em through a flow meter. You are going to save me a lot of time!

[@Chevyguy-Ray]

Very nice way to help us understand the method of tracking down a potential problem in the engine.

[@m.b8257]

The best mechanic , bar none.

[@markh.6687]

Eric: "I've got a dropout, injector 5! (Whoop! Whoop!) I can't hold her, she's plugged up! she's plugged up!" Great work identifying the issues, Dr. O.!

[@diesel46809]

Awesome way to check injectors. Way better then the old bench test way. Great video.

[@VoltageDropDiagnostics]

Boom! One of my favorite tests! I like how you showed that you can do this test without accessing the injectors!

[@kc360awareness]

Seems like SMA shared a video once with you doing this once too. In fact that’s what led me to your channel.

[@VoltageDropDiagnostics]

@@kc360awareness Yup. Happen to remember Keith Defazio doing a meet up video when a couple of us youtubers met in Staten Island? When we were there, we were discussing this test and that discussion is what led us to start using the pressure transducer for this test!

[@kc360awareness]

@@VoltageDropDiagnostics - nice. Old Keith is the man. Funny thing about him is that he had a background in electronics not just automotive. Seems that experience has given him an advantage. A lot of guys like me are weak in that area..... the area cars are most complex.

[@mike_svt93]

Always appreciate the intro explaining the set up detailing everything. Like a professor setting up a lab class exercise. :O Hopefully a follow up video to come.

[@jdtractorman7445]

I gave you a thumbs up just because you are using newer technology and showing us how to use it😎. I don't get why it's so hard for some to understand that testing equipment like this is the present and future of auto repair. The days of using the big engine analyzer/oscilloscope that took up half the wall in the garage are long gone. Keep doing what you are doing Eric and don't pay attention to the naysayers.

[@hichamsaid9472]

this technique is applicable for both types of engine; diesel and petrol. thanks so much

[@DIYDaveOK]

Always appreciate your videos. Love to see ways to use a scope. Thanks as always, Eric.

[@marksd5650]

I’ve learned so much. I’m moving to your town so you will be my mechanic. Best Regards

[@carlbliim4456]

I am glad my days as a mechanic finished before all vehicles were fitted with electronics. My electrical skills are still only basic and I am thankful for the way you sort out the problems .Carl Woy Woy Australia.

[@flagmichael]

I maintained and repaired computer controlled equipment since the late 1970s until I retired 2 years ago. That part does not faze me, but getting to the stuff... I'm too old and stiff for that.

[@ianrichardson9200]

Love your vids! Keep making them because you are good at what you do! Ian from Australia.

[@Auto-Tech]

Wow you got fancy with the screen recorder today. I LOVE IT (no glare from the laptop screen) 👍

[@jamesu]

Thanks for the video Eric. Never used the scope for injector drop testing. Always used the gauge. The printout from the scope would make showing the customer easier.

[@donaldrackley626]

South main auto's the best of technology you can ever get if an autos can't fix it no one can . Fact

[@JuanHernandez-ov8wv]

Great video Sir. i appreciate t knowledge u teach us.i have done similar test with pulse injector generator n a fuel pressure gauge. Funny thing is i have seen injectors failed at 30k miles on some newer cars. So if a cars injectors have lasted near 200k means customer has tried to keep good maintenance with their vehicle.

[@jorgefernandez-mv8hu]

You are thorough it makes sense. Thanks for the video.

[@wolfox2007]

I had a multiple lean misfire once on the usual Shovrolet suspect. It turned out to be a misfiring bank 2 coil pack on an LQ9 power plant. It would enrich the downstream oxygen sensor so the computer was pulling fuel until the other cylinders would suffer and the engine would knock being so lean. It would cold start idle really rough too. I drove it on short trips until the coil pack completely burned up and burst it's plastic case. Once replaced? Good as ever! I am a diy guy and did the legwork... checked plugs, wires and for fuel and air and cylinder compression. But I nailed it being patient and without advanced tools and equipment. Everything being equal I thought I'd share. It was confusing as to how a lean multiple misfire could occur that way but yup, check ignitor packs too... then think backwards all the way back to the ECM. Edit: i gave instant thumbs up for appreciation, your hard work and time away from your bread and butter to help us plebians. 👍🤙 A computer can signal an issue and drop a code. But what attached systems and sensors are at play? What else could it possibly be? I had nightmares of a broken valve spring or an injector at fault... but a marginal coil pack was all it was. $45 retail over the counter fixed it. ^.^

[@mikecont9742]

VERY INFORMATIVE. GREAT VIDEO.

[@jimithekid719]

You the man Eric! 🤘🏼

[@russellstephan6844]

I'm an intense DIY'er with a hydraulic H press, welder, oxy/acetylene rig, and a whole bunch of other professional-grade implements gathered over the decades. If one buys just a couple of well-used but in good shape cars, the cost of an oscilloscope *and* a bi-directional scan tool are easily justified on a cost basis alone. Never mind the avoided hassle of dealing with less-than-competent retail repair shops. Please keep showcasing oscilloscope diagnostics. It's fascinating on two levels. One is the bringing-to-bear of a killer piece of kit. The other is a peek behind the curtain of the electrical activity of the modern automobile.

[@WisconsinWanderer]

Appreciate your info needed now more than ever. You and yours be safe☮️😎

[@danieldelpha1315]

Great to see a different way to do drop teat

[@johnsantiago7715]

Thanks for Sharing Erick 🔧

[@charleswilson3949]

Had 03 chevy Malibu doing the same some thing so lean it would miss a little when cold it had bad Injectors you taught me something very useful here

[@ashpalmer1365]

Follow up video after injector replacement! 4 bad or 4 good? We want to know 🤔

[@timothybarney7257]

@@pz5232 It looks exactly the same as an old injector, just much cleaner.

[@echowhiskey2411]

that one that was pulsed that had slightly less was most likely the culprit. a bigger drop would indicate more fuel thus a richer exhaust. And I know what you're going to say, "but what if there is so much fuel in the cylinder it doesn't combust at all and then that cylinder sends straight oxygen into the exhaust" That PSI difference isn't enough fuel to cause a fouled plug and not allow combustion at all though. I hope this helps

[@rafaelmarin1963]

Indeed.

[@flagmichael]

My guess: the one with more drop is hanging open for a but, which becomes a larger part of the "dwell" time as the rpm increases. The excess fuel in that time drives the ECM nuts. Just my guess.

[@robertmedina6875]

Awesome video! Thank you!

[@dougkubash8673]

Great video as always! Fuel pressure is so important - small example - we had a F-700 with a 429ci fuel injected gas engine that had exhaust that smelled so rich it would burn your eyes. It had low fuel pressure ended up being the fuel pump. My theory was the injectors didn't have enough pressure being delivered and were squirting fuel instead of atomizing.

[@carltonlane8931]

Thanks for your thoughts,interesting,thank for the videos.

[@raymondhorvatin1050]

enjoy your videos always lots to learn

[@alex1949]

Just did the same thing this weekend, but with a mechanical fuel gauge on my son's H3. Same difference. I did use my Autel to trigger the injectors, but it was easier than using my old Actron injector tester. Hard to nail down the issue since no codes are stored. Traced it down to a possible a wonky variable valve solenoid since the data is showing valve timing variance high very intermittently. Not long enough or often enough to trigger a MIL, I guess. Just cant troubleshoot all theses problems without these advanced tools!

[@walterk1221]

Brilliant modification to the tester lead! I am kicking myself for not independently deciding to do the same!

[@donaldrackley626]

Love it Mr ow your getting me all fired up boy

[@Sergio09354]

excellent video like always! keep up the good work

[@frankmuschetto3385]

Enjoyed the video. As usual, very informative and helpful. Simply watching you go through your logic to diagnose an issue is very valuable. The fact that you have to use technology is not an issue but rather an indication of today's world. Technology is a facilitator, actually a requirement, in today's world. Moreover, you're in the business to make money so using available tools to do so is totally understandable and the right thing to do. Moreover, in this case with 200,000+ miles it only makes sense to just replace the injectors and not run up the diagnose bill any further. Pulling the injectors to do a flow test would be nice but not necessarily a cost justifiable solution. The injectors have a ton of miles on them, and this is a FCA product, so replacement is the least cost solution. Would be interesting to learn what happened and what the eventual outcome is.

[@donnierobertson3088]

Great job and video like always

[@SimpleElectronics]

Hehe I love the "smoke 'em if you got 'em" attitude to the picoscope vs an analogue gauge! We just got a transducer at the school where I teach the trade, but I haven't had the chance to play with it yet!

[@otisplunk2599]

Dear Eric: I checked the injector flow and they have identical pressure drop. Just wanted to save you some time. Don't bother to check them yourself. Luv always, the customer.

[@flagmichael]

Oh, good! Some reliable information for once! Not like the windshield pump thing.

[@sergiorodiles4101]

Nice video!! The more I see that picoscope in action the more I want one (at least one I can afford)

[@brentowen9480]

Great diagnoses. Glad you're recommending all injectors...was curious as I was watching what recommendation you'd make. Ma'am the fuel injectors are "relatively" messed up.

[@TheDisgruntledMechanic]

Thanks! Love the Pico videos. Now off to download the pico 7 automotive software!

[@lackeydehackey405]

Back from buck gutting are we? Glad to see you back. And Evan is the new Marie!

[@grad0n]

Cool test!

[@wyattoneable]

Thanks Eric.

[@jeffreyfrank1194]

my cup of tea thanks

[@automotivediag8502]

Great job

[@spelunkerd]

Wow, lots to unpack in this video, an entire course summarized in a 12 minute video. Excellent! On the second set it is interesting to see the duration of low pressure was so much shorter in the second one tested, I wonder why. Is that just an artefact made by difference in when the fuel pump reacted? With all the effort to get at those, I would replace all and move on. A digital graph beats analog readings, nice to see another use for pressure transducer technology.

[@gregp05]

I got the same tool for injector balance, but like you say, no "known good" to compare results with leaves you only being able to compare to the other injectors in the car. Great video! I like the look of the new pico software.

[@markh.6687]

(Jordi LaForge voice): "We'll have to compare the width of the pulse wave modulation frequency cycle to determine which of the plasma injectors is bad."

[@markferraro5250]

Very good EO thanks

[@michaelsawyers1002]

Thanks for the video

[@cacanovotny]

Thanks for the video. I just think that since at the beginning you said it has lean code, points towards 5 plugged injectors and maybe 1 better one, rather than 1 giving too much.

[@flagmichael]

One of the complications when dealing with a mixture code is that the ECM is only willing/able to adjust the bank. When one cylinder is misbehaving that can produce unexpected results. In this case, it probably chased the rich one but reported the lean condition it caused in the other cylinders.

[@dennisbranum719]

Good job!

[@AntonioClaudioMichael]

Good video Eric O Great work on this one @SouthMainAutoRepairLLC

[@marcharris4176]

This seems way faster than The good ole fashion scan tool with a pressure guage. Using the harness instead of going directly to the injector saves a lot of time. Great diagnoses.

[@tomhope4613]

Been having rough idle and slight miss but drove fine till the eml came on.......injector failed. Now replaced and running perfect....... trust you to post this just after 😂

[@IAMNOSLEEP]

Thanks for sharing... Cheers.

[@HandyC]

Nice work on getting picked up by a picoscope news release. Strange seeing that in the UK marketplace.🤣👌🏽👍🏼🎖

[@kenschneider5556]

Great video! Would be interesting to see how the waveform looks with the vehicle running. I would imagine the results would lead you to the same conclusion.

[@howardboyd7764]

Thanks Mr O. Great example of (thinking) things through. A vehicle with 200K miles, just replace all the injectors, not just the two suspects...

[@dennisgundlach87]

Thank You

[@PhillyDee215]

Yup time for some injectors👍

[@jamesbruno5896]

Cool beans Eric!

[@jeffroach5716]

Really nice diagnosis. My engineering experience makes me think the only good injector may be 5, but 2 and 6 are definitely bad since the pulse width is shorter than the other four indicating the injector may not be responding to all the pulses.

[@mikechiodetti4482]

With that many miles, once you change one or two injectors, the rest are sure to cause trouble. Change them all. Give the customer all the info or facts and let them decide. Great Diagnose!

[@misterhat5823]

Short of visible damage... When would it ever be a good idea to replace just one or two? Labor is the big cost here and it's just about the same to do them all.

[@Qusin111]

I think your logic is sound, one rich injector will make an uncomplete burn making the oxygen sensor think the system is rich. I can't help but notice that your diagnosis tools do not have a hammer side, this is a good thing. :) PS if one is failing or 5 doesn't really matter, either something compromised them which could be a number of things, best to change them.

[@robertmoura7546]

Hi, once again I say do what you have to do cause the bottom line is solving customer problem and making him smile and getting paid and turn him to be a regular, most cars nowadays injectors are under a manifold or something else which makes it difficult, to me it's a tough decision if 1 is good and 5 bad o vise a versa incase like this here in Brazil we pull them out and do a bench test on a 4 tube injector test equipment checks for leak, flow, spray pattern and amp draw which most of the times solves sticking injector or plugged, thank you for sharing

[@HUBBABUBBADOOPYDOOP]

Definitely change the oil now too.

[@arnemalmkvist8553]

You read out abd fixit 🙌👏👍

[@Tnenamrep2]

Awesome! Ty.

[@khndenmark]

Informative video, but it will be nice to se the fix.

[@skokie23]

Great vid Mr O!! What was the fix? Thanks and keep em coming!!

[@THEDRAGONBOOSTER8]

Yep agree..

[@ebuzek3648]

Do we get to see a video of the fix? And what are the correct reading for the injectors. Keep up the great work Eric!

[@letstrystuff5171]

Hey Eric!!!

[@josephlanguemi]

nice