PCM maybe

Reply Subscribe

Thread Tools

Search this Thread

Jul 24, 2013 | 07:44 PM

#21

ugod02010

Thread Starter

Launching!

Joined: Aug 2012

Posts: 259

Likes: 0

From: Johnstown, Pa

Quote:

Originally Posted by Ed Wright

One test they taught us at the GM Training Center was a simple "slap test", start your data logger, then slap the ECM/PCM. If the car misses, you found it. If not stop the logger. Play it back and look for data spikes. If it gets extremely hot it could be the problem. High knock counts or mis-fires are seldom the computer.
Any competent tech could find a mis-fire. Injector driver issues are about the only thing in an LT PCM that would make one miss. Very easy to test with a DSO. Bad or missing wave forms will tell the tail.

Cool. Nice to know. I think I may have found the problem. I've been convinced it was spark side of things since the entire fuel system is new. Well less than 3months old. I got out the old harbor freight fuel pressure tester I only have 20 psi on there with the key on engine off. Doesn't bleed down. When its on and vacuum is off the regulator still around 20-22 and as soon as I rev it a bit it drops to 16-18psi. The pumps under warranty and I have a trap door so I pulled it already just waiting till Tom. And I can throw the new one In. Ill check back and let u guys know what I found

Jul 24, 2013 | 07:57 PM

#22

ugod02010

Thread Starter

Launching!

Joined: Aug 2012

Posts: 259

Likes: 0

From: Johnstown, Pa

What is a DSO?

Jul 24, 2013 | 08:24 PM

#23

Ed Wright

9-Second Club

iTrader: (1)

Joined: Feb 2002

Posts: 3,397

Likes: 9

From: Tulsa, OK

Digital Storage Occiliscope. Can't use an analog 'scope. Don't use analog scopes or volt/ohm meters on a ECM or PCM. Always use a digital meter with 10 mega ohm impedance. Anything else pulls too much current.

Jul 25, 2013 | 05:34 AM

#24

ugod02010

Thread Starter

Launching!

Joined: Aug 2012

Posts: 259

Likes: 0

From: Johnstown, Pa

Sounds Expensive$$$$. LOL. I called the auto store they ordered me a new fuel pump so after work today I am gonna throw it on hopefully it works right agian.. Just a note for everyone who has a miss or a bog, Check both fuel and spark. This is the second time now that my car has sounded acted like there is something Going on with the ignition side of things and turned out to be fuel related.. (well Ill know for sure soon)But at only 20psi when idling I would say its probably the problem. But the car really seemed to be an ignition issue with missing in the higher rpms. And Shutting off on the highway soon as the revs hit around 2500-3000 rpm. I will post up agian tonite and let you guys know what happens..
Thanks to everyone with helping me out narrow this mess down!!!!
And hope you guys got a laugh from the pcm article!

Reply Subscribe