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Computer Question...

alphadeltaromeo

alphadeltaromeo

Diesel Enthusiast
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Location
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As a note I have an Auto Fundamentals book that I'm referencing for troubleshooting here and there. I found the section on injection and thought I'd share a bit of it:

"Injector Pulse Width refers to the amount of time during which the injector electronic solenoid is energized, causing the injector to open. Pulse width is a measurement of how long the injector is kept open; the wider the pulse width, the longer the injector stays open. The amount of fuel delivered by a given injector depends upon the pulse width. Pulse width is controlled by the computer."

The book goes on to discuss timed and non-timed pulse fuel injection.

Anyway, without fail I get the pulse width error (both long and short) every time I drive the burb. Secondly the cruise control won't work. Now from what I understand if there are any problems at all CC won't work. Thirdly there are many times that the burb will shift hard and we'll get a tranny error on the scan.

Trying to clear the code won't work, as the software reports back an error, indicating that the code can't be cleared. Now, I get home, shut it off, come back to drive it later and no error. Sometimes on a cold start it just runs rough, like the PMD is bad with fish-biting (I have the Heath remote PMD installed). Then at other times it drives like a dream.

I'm providing this information to help me to troubleshoot and then make a few decisions.

From what I've provided, what is the possibility that the main computer has an issue? If it did, would getting it flashed with a new program (performance upgrade that is) potentially help to resolve issues, or could there be a physical issue causing problems? Any idea what a new computer would cost or is that not a good option?

Your wisdom is appreciated!

Andy
 
When we replaced the head gasket the batts were out for a week...and then when we buttoned it all up it ran like a dream for weeks before the issues described were occurring.
 
I'd be willling to bet the ground on the back of the head is broken. Probably did it when doing the HG's. I think there is a sticky on grounds and where they are. I would start there. The pulse width could also be a sign of a dying IP but given the other issues I'd go with that first. PMD's "usually" don't throw codes but could definitely cause the CC not to work. They will not cause smoke but could cause the engine to shake violently. I think a bad gournd could explain alot though.
 
Ok good input...will check that tomorrow. With that said the IP and the injectors are new (doesn't mean the injectors were set correctly though, considering that I had to adjust the IP timing correctly anyway). The PO had the work done, but the PMD was shot and they were unable to resolve the issue, so they sold it to me :)
 
Just talked to Jon (son) about that one in particular. He said they forgot about it initially when they put the head back on. After realizing the mistake they retrofitted it on. I'm still navigating carefully through the "grounds post" and will inspect first thing tomorrow to see the lay of the land for all grounds...if this solves the issues, I'll be happy lil camper.
 
Those grounds on the the last intake stud bolt and the ones on the tranny dipstick bolt, if NOT connected the truck will not run.

Been fighting these with WTS ghost......There is another ground behind the dash to the left of the PCM (G102 or G202, I believe).......because of the hidden location, must get skipped over all the time.

JMHO...FWIW
 
Took a few hours and cleaned all the grounds very well yesterday. Made sure to use an angle grinder to help clean surfaces. Also the grounds by the dipstick bolt, I bonded that to another head stud (the batt ground stud) as the dipstick bracket was painted and I didn't want to just rely on the contact with the stud. Anyway, still didn't resolve the issues described.

So I'm curious if the grounds are all good, what else could be possible...I'm thinking only the computer?
 
Could be more than one issue or the PMD or IP. Have you cleared them to see what comes back ? That pulse width is not a good thing. IIRC That is the armature hanging up on the ip. Could be more than one issue...Didn't do any of this before the HG job ?
Could try a good douche of Diesel additive and 2 stroke oil.
 
The pulse width error does not refer to the time the injectors are commanded. Its similar but not exactly the same thing. The injectors are commanded by pulse width, but the pulse width that the scanner shows and what the DTC is all about is time for the IP Fuel Solenoid's metering valve to close after the pulse width is over. Pulse width to the PMD has the PMD power the Fuel Solenoid to hold the valve shut, then pulse width ends and it take X milliseconds for the valve to reseat. So this error can be caused by lack of lubrication for the valve to move freely. Or scratches from when it wasnt lubed. A weak fuel solenoid (rebuilt may reuse a Fuel Solenoid with 180,000 miles on it), or a bad PMD can cause it. GM actually had a TSB for these codes that said to first just replace the PMD. Air in the fuel may cause this little hiccup as well, as it can cause all sorts of strange things.

Since I suspect you have been lubing the fuel up with 2-stroke oil, then I would put the problem in the area of worn IP or PMD.

When did you set the timing, and how did you do it? What is it set at? If you have access to the scanner, check the reported pulse width while running, a healthy system will vary from about 1.5-1.9ms, but those that hover around 2.0+ have some wear or issue. And also check what the idle fuel rate is.
 
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