Diagnosing Chevy Corvette That Stalls Out But Has No Codes 

That's a great diagnosis. But the problem is how do you get paid? This industry rewards ignorance and stupidity. If I told the service manager that I need 4 or 5 hours diag time (@ $200.00 per hour) he would get another tech to fire the parts cannon. Managers love it, the mark up on parts along with labor to install. Not a care in the world if the problem is solved. I've been in dealers for 48 yrs, and each one is the same.

Great job! I think the hardest part of analyzing scope patterns is knowing what looks valid and what doesn't look valid, especially if you are in a shop that works on every make and model.

That scope is incredible. My dream tool. Great video. You guys are next level. Professor is an incredible teacher. And shout out to the camera man. 😂👍

How squeeze years of knowledge, experience and butt kickings into a 35 minute video!

10:46 I had a Super Trooper moment! Mac: "What about that little fella?" Thorn: "OH, that little guy, I wouldn't worry about that little guy". Man I enjoyed that movie! 😂

I have learned so much from watching your videos. Thank you so much. I've been a mechanic for about 4 years now, but im starting to want to get more into the deep diagnostic side of things with scopes and reprogram and flashing awsome awsome video blessings and shout out to your boy the camera guy 🙌

I can say for sure, if this car was in my bay I’d be holding my breath until the repair was made. Because these types of problems, there’s no one single test that tells you what the main issue is. Good job

I’m 24 minutes in and I’m getting impatient 😁 but I shouldn’t because you are showing us your diagnosis process of excluding one component after another instead of just showing the cause of the issue. This is much more informational and valuable and it’s why I like watching your videos so much! Thanks! Happy holidays!

Thank you for actually diagnosing the issue and proving the problem. Not many technicians do! I’ve been watching a lot of Bernie Thompson’s videos and will now be watching yours, too.

That's a hard one for a lot of top notch techs.! Great find.! Congratulations..!

The importance of using an oscilloscope is vital - as demonstrated here fully. Just today I got off the phone with a potential employer - Honda dealer , their position on scopes is “We haven’t used those for years, we use scan tool data” - I thanked them for their time. Keep up the good work fellas!!

Had a similar scenario on a OBD 1 TPI 7730 setup.... Gm 350CI engine, Gm Fastburn heads and LT4 Hotcam, GM sold it under the "ZZ430" crate engine... Once the car was being tuned properly and the AFR ratios being dialed in via VE Tables to properly reflect the modifications made, it suddenly out of nowhere developed this rare "TIP IN" dying out situation like the Vette in this video.... You could start it and leave it in P/N and rev it, or idle all day long until it drained the gas tank dry..... But soon as it went in gear, 50% of the time it would sputtered out...... Worse part is it wouldn't throw a code that stayed due to engine quitting each time having to restart... Would start back perfect and idle every time! It finally took doing a data-log and watching it via playback to see what was happening... Code 33 would flash for a split second (CODE 33 = HIGH MAP) reading and the engine would go crazy when it would happen even though it was just a split second event. Once MAX MAP was set from (67 KPA to 80 KPA ) due to overlap of cam, (PROBLEM SOLVED)! Never had that issue again.,.. So whenever you install a cam with overlap or that can cause less vacuum at certain spots, be sure the settings in the ECM are changed to compensate it. But none the less, it took a logger like this to find it... Anyone can be a "PARTS CHANGER", and keep throwing parts at something, then still have the issue... A real "MECHANIC" properly diagnoses the problem, figures it out, then fixes it for good or tries to..

As usual a superb presentation with a step-by-step elimination of all possible causes , enjoy watching and learning even at my age 😊

Video of the year, good video to wrap up the year with. Thanks for all details and tips. BTW, the camera man, AKA your son. does an outstanding job filming and zooming in so close to show us everything. Thanks both.

Another great video with absolutely great info

What you're explaining here is 100% spot on what is happening to my 2005 Dodge Ram 1500. I don't have a scope. I've been thinking for awhile, it's my PCM. I think I'm going to just take a shot in the dark. And change it. It runs for 5 mins-10 mins and shuts off. Happens while driving as well. It will buck and keep going. Gets slightly better as it warms up. I've also noticed it charges over normal. Which is not normal. Changed crank sensor, plugs, wires, coils, checked everything. Still stalls just like that corvette. I think the voltage regulators in the PCM is going bad. My PCM is around $300. Think I'm going to change it.

Great stuff Sherwood. Need more like you.

29:06 I‘d love to know that saying! 😁 30:50 I’m here for the camera work! 👍😁 33:38 Yes, you definitely need a scope for the less obvious faults. You also need capable technicians who know and understand how to use them.

Great job! The scope doesn’t lie.

That is outstanding troubleshooting. Narrow down the problem and isolate the issue instead of shotgunning. I did much of the same when diagnosing networking issues.

The microcontroller clock is usually very robust and not a common exception reset source. There are many other reset sources that are much more likely to cause a ECM strategy reset, for example a faulty power supply or brown out event. It is clear from the scope trace that the ECM reset and batch fired all of the injectors at once, which means they overlap (occur at the same time). There are other indicators of ECM reset. One would be a freeze on real time data from a scan tool. Meaning if a scan tool was set up to get periodic real time data from the ECM it would show that when the car shut down the communication also stopped.

Glad you were able to diagnose the problem. Great work great video.

I love the Hz plot feature... Great video

Another great ONE !! Thanks to the Camera Dude : )

I had a 2007 with 39k come in my shop with this problem. Lucky it had a code complaining about a internal module failure. I replaced the battery and module. Nice work with that scope!

What a great video, showing how you can use a scope, with a step by step diag plan, to exclude or confirm each component that could cause the issue. Very informative! Unfortunately my Hantek 8 ch scope doesn't have anywhere near the same specs & features as your AES wave scope. But I don't actually wrench for a living, so it fits my needs. I'm an internal service "advisor", but I have a lot of old school experience & doing all I can to learn the new tech, so I can try to help out my young, inexperienced guys.

Highly unlikely crank or cam sensor could reset the ecu, both low power 5 or 12 volt reference, hall effect (magnetic) - so very little ability to spike anything. 3 common faults with electronics especially at this age are: Faulty capacitor(s) (not usually an issue in automotive electronics) , weak component (often from static damage - which can occur early in life but show up much later) or most likely a dry solder joint. Solder is basically crystalline, oxidation forms along the lattice structure causing bad joints - or just badly soldered to start with. Temperature cycles put stress on the solder joints over time. Holden VN V6s had common failures of ECMs at 160K Kms/100K miles. Resolder was an easy fix. Worth a visual inspection of ECU connectors and board - and using a soldering iron (proper electronics one) on and any (or just all) even slightly dodgy looking joins.

Thanks Sherwood for this valuable information on diagnostic every aspect of this vehicle.

Good call,I also check 5v reference when having a ecm reset

Learned fifty years ago the value of a. Ancient scope when cook guy captured my car I. A garage avd said figure it out . I did and it was great

ATS escope 8 channel is On my 2024 wish list for sure

Nice shout out for Bernie! Nice job!

What made you decide to scope all 8 injectors first? Thanks for sharing!

I've been dealing with a similar problem with a Pontiac 1996. But this one is double firing injectors. Cam and Crack signals good. Pwr grd good. We called it a pcm. Customer is waiting till after the holidays. So hopefully that is it. But you are right like barnie said need more channels in the scope. Specially me with a 4 channel.

That escope is amazing. Got to use it for a week at the shop. Need to invest and buy one

I remember the old guys who had the old analog scopes and parts books thicker than 4 telephone books!

Very interesting, these type problems is what separate's the men from the boys as far as mechanics are concerned.

That's really helpful technology right there

Scopes are one of my favorite tools to use. But I was never brave enough to do my own shop....

Great diagnostic tutorial.

Excellent skills

Great video and explanation- I would t ever own anything to that caliber but it is great to see.

Thank you AND the camera guy for another great video! I hope you and your families have a wonderful Christmas!

Great video loaded with information thank you.

Ats is a good scope but i dont like how you have to buy everything ats to work with this scope. From pressure transducers to amp clamps and secondary ignition. Pico will work with any custom probes. Otherwise its a great scope

Great video, nice scope. Keep in mind the Fast Fourier Transform (FFT) analysis is looking at the frequency content and relative power contained in each frequency bin of the time based signal out of the sensor.The bottom axis is frequency in HZ many those anomalies are digital signal processing phenomena or electrical noise. Probably more useful just to look at the time based signals out of transducer, and overlay it on top of a good trace of the cam sensor. The vertical axis is only useful for relative signal power and comparison purposes. Especially if your vertical axis is displayed in decibels. You really can’t scrutinize the FFT plot unless you have a baseline plot of a normal functioning sensor response. So if you see new frequencies at high amplitudes that weren’t present before, you know something is wrong

Amazing troubleshooting.

Very informative. Really good video. Was able to learn a lot. Thank you guys.

Sounds like the mosfet drive circuit took a hit during the jump start that causes the mosfets to all close circuit at once. MP detected this and shuts down. Had a Nissan doing the same thing but only on one injector.

Great job , I agree with your diagnosis procedure / process 100 percent . I watch Ivan, scanner danner, Eric o Bernie ect.. all work logically and decisively . I understand this part , i have been doing this type of work in a different industry for many years , automotive repair as a hobby. What i would like to know is how do you charge for a job like this? Thousands of dollars worth of test gear , hundreds tied up in software subscriptions for wiring diagrams and specs and hours and hours of diag time. Thanks for any incite

Great work 🫡

THANK YOU SO MUCH FOR CALLING naturally aspirated A engine, I ask others what are you going to call your tesla a engine? No they will call it a drive MOTOR they won't call it a engine, so thank-you fir calling it a engine, sry for rant. Grt video, and when you are as professional as your shop is, always grt to hear you refer to people as your client versus customer, we're not at autozone lol

Great video! The one thing about those scopes is that there isn't any channel labels. I would get confused running 8 channels without labels to remember whats what when I went back to look at the captures.

just sitting here thinking of other tests you could do to to eliminate what is causing a reset condition. Could you run a bi directional test, such as commanding the purge valve duty cycle, lets say 50%, with the KOEO. That's as long as the bidirectional test doesn't have a timer. Watch the purge valve signal at the valve itself using your scope. If a reset occurs, you should see the purge valve command signal drop off. If it drops out, you just eliminated coil spikes, excessive AC ripple, CMP/CKP glitches, etc.

Another excellent video

How many hours of diagnoses did you charge versus how many hours you have into it?

Great Diagnostics. That's what people pay for.

That was great 👍🏼 ! Thanks

Great diag for sure!! You’re going to have to take over for Bernie if/when he retires!

Great video shout out to your son good work.thanks for sharing

Intermittent faults are the most difficult to diagnose.

This guy is a great teacher & he can really read a scope. I haven't seen GM put the PCM in the wheel well in a really long time. Usually there are in the engine bay. Reminds me of the old days when they had cracked solder joints on the PCM. The test was to tap it lightly to get it to work again Then you knew it was bad.. Great video.

Love your videos. I have the escope and it's really nice that someone besides Bernie uses it to make diag videos. Those that have a pico this can be don't using the math channel feature on pico. But it's way way way easier on Bernies scope. The escope has so many more features that are way more user friendly. I have used both and escope wins for sure.

Sure do appreciate all that you do it's impressive thanks

We send those to the dealership and fix it after they diagnose it for us! That way customers can't blame us and we don't have to buy $1,500+ Scanners and Accessories!

Good job Sherwood. I remember back in the OBD1 days with GM ECMs and their failure prone issues, we would give the ECM a few light raps with a screwdriver handle and get them to cause stumbling/stalling issues. Wonder if this might have helped identify the PCM as the issue?

Happy Christmas, Royalty Auto Service 👍 From Nick Ayivor from London England UK 🇬🇧 ⏰️ 20:24pm Good Evening

Wow. Amazing to see how a multi decade technician explains how he thinks. Diagnostics can lead you into a rabbit hole no doubt about that. What caused the ECU to fail?

29:00 I just want to know what you couldn’t say on RU-vid. I’ve been working on computers forever and I agree, computers almost always fail due to bad maintenance or an associated gear failure.

Good show.

Thank you, camera man

More like this please

if the ecm is bad, it would probably wouldnt throw a code, since it bad it wouldnt self diagnose an issue with it self, im glad the ecm did not blame something else and initiate a rabbit hole run

Did it get repaired? Do not see a follow up video? This stuff is well over my head but I enjoy watching and learning.

Beautiful car.

Ever try just reprogram the module? I have had module issues multiple times on equipment. Combine, tractor, sprayer, loader, different equipment. Reprogrammed it and fixed the problem. Software went goofy. Every time the dealer or tech told it won't fix it. Never had one when the issue came back when a reprogram fix it. Doesn't take long and can often cost only time. Just a thought.

Great video, I am surprised there was no code in failure records.

love all the information and great find just want to know if you able to find this without a scope

I have question its this, on chrysler jeep vehicles, that add aftermarket headlights, tipm always has codes for these, what is tipm looking at or for that causes codes, when headlights wrk, my guess is some sort of power and or resistance change it sees, but see all the time when scanning, says headlight and if park light circuit codes if Led bulbs used, can you cure this after using aftermarket lights, not huge deal but didn't know, what tipm uses to determine u changed bulbs, MERRY CHRISTMAS

If I didn't have a scope and like you said no codes could I use a break out box to get to the right direction of the problem ?? Thanks again you guys are 10 stars ! keep the videos coming

Thats awesome that you can call Bernie for advice, even the best techs need help sometimes. But who does Bernie call? Probably God.

Should set a code, but what about a 5V sensor pulling 5V reference to ground.

Never fails when you have an issue but as soon as you tell someone about it it will make a liar out of you happened to me a few times it drives you crazy

I just realized y'all were in the Kings Bay area. I might have to bring something down there if I find myself struggling to diagnose it...

Legend

Well, I'm just gonna change the module and see if it helps

4 channel scope would work. Been a nice capture of a current ramp of the injectors when they all fired at once.

Now if I can just get my shop to buy the ATS scope and tablet combo.

What if In a case were you do an AC ripple test on an Alternator and you have no ripple effect. What does this translates into. Nice job here

Exellent. 👌

Did you guys do a crank relearn on old pcm?

Grasias

I saw the problem right away. The car is not a 1993 Celica or other old Toyota. No charge for my diagnostic service.

Folks that just hang parts, before a shop as you gets to look at it, they spend all there money and leave none sometimes for the real answer, almost like copying off my paper in school, cuz they don't want to put the time in, and they get my d or f, thanks guys. MERRY CHRISTMAS FROM ADVANCED ALIGNMENT, Princeton. ILL.

do you do online diagnostic bro ?

Camera guys rules

Do you know of any budget scopes you would recommend?

Camera guy!

How do you charge the customer for all that time you spent on it

Would the 8 lead hantek show you the same thing?