2008 Hummer H3 Misfire Case Study (Part 1)

Here is the playlist for this series
Visit my website, www.scannerdanner.com for more about my eBook and lectures.
Visit our school www.rosedaletech.org, to be part of my class in person.
Visit http://www.youtube.com/channel/UCs2NZ_wQFDFvV0QOhoZgASA if you would like to be part of my on-line class. For more information on this topic, I have written a “field manual” called Engine Performance Diagnostics which is available at www.scannerdanner.com as an eBook or paper book.
Want even more diagnostic training? Whether you are a DIY trying to fix your own car, someone looking to become an auto technician, or a current auto technician that wants to get more into diagnostics, subscribe to ScannerDanner Premium right here on YouTube. There is a 14 day free trial.
On ScannerDanner Premium I will bring you right into my classroom at Rosedale Technical College. You will find page for page lectures taken right from my book as well as exclusive classroom type case studies. What is so special about these classroom case studies? I pull live problem vehicles directly into my classroom and we troubleshoot them in real time, using and applying the theory and testing procedures we learn during the classroom lectures. There is no better on-line training of how to troubleshoot automotive electrical and electronics systems anywhere!


Mike Brennan says:

There are 4 spots to check when doing leak down. Radiator as well. blown head gaskets will cause leaks into cooling system.

Dennis Gibson says:

Ya im pritty shure now im taking a victory lap. Be4 the real stuff happen. I just dont want no suprises. Hopeing if seen n heard it all lol

guayaco3299 says:

Like always Paul, excellent video..
Learned a thing or two from watching this.Keep up the great work Paul..
Thanks for your time.

Berron Van Cleave says:

My H2 backfires put the pedal to da floor An won’t get over 2 RPMs driving wise it won’t get to 45mph without backfiring bad? Help

Atacama777 says:

Another excelent video Paul, every step perfectly and academically explained, you take the teaching and the diagnostics process to the next level, thank you very much for sharing it. You know, some of my classes, I just wanted to finish as soon as possible, but 46 min fly when you are really learning, 

Mohammed al-ani says:

many thanks for such awesome videos.
can you please tell me what is the pressure value should I have on my injection rail.
my Hummer h3 2007 is running rich and has random misfire p0300 only when I hit the pedal.
and the code disappear when the vehicle is idling.

consaka1 says:

How does the computer measure a misfire occurring.?

ozzstar says:

Looking forward to Part 2, thanks for posting this video


great information

mike r. says:

i would like to see some vacuum testing i use it for valve testing and clogging converter  direction testing on the snap throttle dip and recovery rate. it is such an easy tool to use. i wonder if live scope data on the map sensor can be used for intake valve detection. great video your detailed explainations make it great

peanutbutterisfu says:

You can watch you map pid specially during a back fire and that’s a dead giveaway for a leaky intake valve if you don’t have a scanner with misfire counter. Man I can’t wait to get one of these compression transducers to try out on some European cars.

campen777 says:

Hi paul , another great vid . I would leak down test all cylinders just to confirm no piston ring faults . Having gone this far , the extra 15 min would make me sleep well . Thanks again for a brill vid .

james ford says:

maestro danner   realize videos en español porfabor o  haga un canal de paga en español

Moggie20170000 says:

what brand video camera are you using?

Jeremy Shanks says:

Great example of old school mechanical concepts mixed with high tech tools. I love my scope, but you still have to know and understand how and why the engine components function.

John Norris says:

If we were to rate your videos this one would be in the top….hope we can see the borescope

Michael McNeil says:

God Bless you Paul. Thank you for everything. I am actually a Professional Technician because of you.

Lynx Star Automotive says:

Would have been cool to run a dynamic compression test. Just to get an idea where the problem lies intake or exhaust?

Jesse Lebeau says:

I have sort of a question reffering to the running compressions on cyl4 and cyl5.
I was diagnosing the same issue on the same vehicle a few months ago, and after ALOT of testing I concluded #2 cyl had a leaking intake valve. But what confused me was that when I did running compression tests (with a conventional compression tester) mine too had very close readings on all cylinders, but with a leaking intake valve shouldnt that be evident on a running compression test? I ending up using smoke in each cylinder when on compression stroke and monitored how much smoke came through the intake manfold and found that cyl2 leaked the most (a ghetto leakdown tests essentially.. lol, but it worked, i was having issues with my leakdown tester at that time))
Now I havent finished all the parts to this video so I apologize if this was covered.

juergen scholl says:

Paul, thank you for your work & time.
Were you able to look for turbulances, on the secondary spark line which would indicate vlave sealing issues?

Fausto Gonzalez says:

Awesome video Paul, keep up the great work. It greatly appreciated!!

P Wa says:

I know this is an old video, but my first time seeing it. I noticed that when you set your cursors during the firstrelative compression test, the #1 cylinder cursor reading on your scope was 1.44 (144amps), and on #4 the cursor reading was 1.27 (127 amps). Mathematically this is an 11.8% differential between the two cylinders. But when you did the compression check, the #5 cylinder was at 150psi and the#4 was at 125psi for a 16.7% differential. I want to assume that the difference between the compression check and relative compression check is because #5 cylinder, which you didn’t measure on the scope, would have been higher then#1 cylinder, or approximately 1.51 (151amps), which would have made a 16.7% difference between high and low cylinders. Is my assumption correct? Also, apart from the fact that you are in a classroom, can I rely upon the fact that there is an 11.8% (16.7%) difference between the high and low cylinder current draw and skip the compression/leak down test or is that a shortcut to trouble? Basically is the mathematical calculations based on current draw reliable enough for a diagnostics? Thanks

sivaraj palanisamy says:

you can also use smoke test into the cylinder 4 directly Paul..to nail the issue.

DIAG kar says:

Hello Paul 
Why you no longer use PICOSCOPE?

sivaraj palanisamy says:

Paul, I learned about honesty from you. I liked when you say that even after 2 years you are not comfortable. How many are there who tell others they know everything when they read just manual. You are exception. 
1) Million dollar benefit in this video, you gave a tip, that when you compare good to bad cylinder at idle, disable spark of both cylinder, so we are comparing both cylinder with similar characteristics..I have bought video like you who explained this and i remember his name John Thornton.. Even he have not given this technique.
2) I really thought you will stop making such vidoes in your free channel and you might post only to your premium, you proved that i am wrong, you have still got awesome videos to this channel and being worth to be part of this forum as well. You are balancing well between both channel and not letting down ..
3) I do like PICO then snap on especially on compression test with transducer becasue you can zoom to greater extent. Second, you might want to zoom and see the degree at which intake and exhuast is opening the valve. The one that is mechanically bad will open much earlier or in advance.. this is my 2 cents..

Last but not least, you never allow any of ur subscriber to think they learned everything. everynow and then you have got one or morething which is new for others. Unbelievable..  Great Job have no words..

sandy anderson says:

Hi paul this mechanical problem would it have shown up on a vacuum gauge sandy ps what is the video mic u r using

pedro munoz says:

from what i have learn it helps if you have a Transducer Compression Hoses (High-Strength)  because you loose valve data from pressure lost true the compression hose also you have a pico scope right i i think it would have been bettter or what do you think also there is a tdc software that you use so that you can lay it over and see if exhaust or intake are advance or the opposite also with the pc base  you could over lay them together and they should be a replicate of each other this is really fresh in my mind because i just took a class on that and the possibilities are endless 

Cody Wichman says:

is there a reason you used a 2v scale and not 60amp current clamp preset?

timothy essex says:

Hi Paul I set up the compression test sinked with the trigger wire on a mini cooper s just to practice getting the waveform on my vantage pro but I find on cranking the spark was not at tdc this was a good running car no faults this car has a 3 wire waste spark system am I doing something wrong or is this normal to have a spark but for tdc ? Ps it has a super charger if that makes a difference.

 Write a comment


Do you like our videos?
Do you want to see more like that?

Please click below to support us on Facebook!