ECM/VP gurus needed

diesel_importer

diesel_importer

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Oct 21, 2007
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Well, I thought I was beginning to figure these things out. I've replaced lots of ECM's and VP44's on these trucks, but I've got an 02 chassis cab 5 speed whooping my @ss. Truck came in with a complaint of: surging/bucking when driving, similar to dead pedal but more rapid. Found TPS code, couldn't find dead spot, but swapped it out anyway= no change, except TPS code won't come back.

Drove the truck more, watched pids, finally condemned the VP, even though it's only got 20k miles or less. Swapped the VP out= no change. Figured I would slap the only ECM I have on it (from 01 auto truck). Truck runs perfect except oil pressure doesn't register. OK, I've found the problem right? Order reman ECM by vin number. Comes in, swap it out, truck idles for 30 seconds and dies, won't restart. Throws no comm code. Swap auto ECM on it, runs perfect again.

Sent ECM back, get another reman. Now the truck runs, oil pressure back to normal, but cutting power just like it did in the beginning. I'm at a loss.


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Does it stumble when using the cruise control?

Do you have another rig to try that reman ECM in? Curious if it would do the same thing in a different rig?
 
Ol Blue, thanks for the info. I'm about to try it on cruise. The APPS doesn't fall out on the scan tool. I knew the oil pressure had to do with the sensor. I'm going to try this ECM in my dads 01 5 speed pickup.


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Only thing I had time to do this evening was test drive with cruise on. Doesn't help at all. I put a Timbo Apps on this truck, it didn't help the issue, but it has yet to throw an Apps code since.

Seems like a crank/cam sensor usually make the truck die or run rough.


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I agree that normally they run rough but my brothers dually would occasionally act like it was going back to an idle and back up(lose maybe 150-300rpms.) I did everything I could to the apps, including mine and a known good one. Swapped map sensors(for some reason), ecm and such just like you did. Eventually just tried both can and crank sensors. I have no idea which one fixed it, and he barely drove it after(500 miles) before we started pump swap.
 
These trucks ran fine when they came from the factory, those to all those who have tried quick fixes seem to be more band-aids of the really issues.

Based on research throughout the different forms, I would try the following:

- Check Alternator for excessive ripple (a fellow form has a great write-up)
- Clean/check all ground cables (age/climate = corrosion which adds resistance)
- Check all connectors
- Check harness for breaks/wear marks (these trucks are getting old)
- Factory APPS assembly (expensive yes, but calibration issues of aftermarket come to mind)

- Auto Part Numbers Part # AP63428 OEM P/N # 3970084, 53031575AH
- Manuel Part Numbers Part # AP63427 OEM P/N # 3970085, 53031576AD
 
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I'm going to look at the harness some more. What's throwing me for a loop is how the spare ECM I have makes the truck run perfect.


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diesel_importer said:
Only thing I had time to do this evening was test drive with cruise on. Doesn't help at all. I put a Timbo Apps on this truck, it didn't help the issue, but it has yet to throw an Apps code since.

Seems like a crank/cam sensor usually make the truck die or run rough.

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Click to expand...

That is a different issue then. Too bad. I was hoping we would be able to help each other figure it out. With your ECM success, I'm tempted to try yet another ECM though $$$.

Good luck and keep us posted please.

~OB~
 
Nighthawk said:
These trucks ran fine when they came from the factory, those to all those who have tried quick fixes seem to be more band-aids of the really issues.

Based on research throughout the different forms, I would try the following:

- Check Alternator for excessive ripple (a fellow form has a great write-up)
- Clean/check all ground cables (age/climate = corrosion which adds resistance)
- Check all connectors
- Check harness for breaks/wear marks (these trucks are getting old)
- Factory APPS assembly (expensive yes, but calibration issues of aftermarket come to mind)

- Auto Part Numbers Part # AP63428 OEM P/N # 3970084, 53031575AH
- Manuel Part Numbers Part # AP63427 OEM P/N # 3970085, 53031576AD
Click to expand...

Cheap band aids? I've read that several times trying not to take it as an insult....can't get there.

1 new VP, 1 new each sensor (MAP, IAT, Cam), 1 Timbo APPS, 3 different ECMs (none were new). Testing and diagnostics per everyone's suggestions with the exception of wrapping the wire loom at the firewall with a conductor where each end is run to the negative post of the battery on that side of the rig, plus others not suggested. Then onto discrete component filters with guesses at frequency, and currently back to hoping to find a loose pin somewhere.

If you have a specific suggestion, please say so, but with out the sarcasm please.

Sorry for the tangent Diesel Importer.
 
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Could you just unhook the alternator to test the whole "induced voltage" theory? Just thought about it......

Now I've had 2 ecm's act the same way on the same truck. The original and the reman.
 
Yes. You'll get a CEL.

If you pull the charging wire, it will tell you if there is cross talk between conductors. The problem is that there are multiple conductors that run at the front of the engine and can still have induced noise if the alternator is turning. Try it first to see if it helps.
You could pull the connector and the charging wire to "make sure". Note that there is very little room back there to turn a wrench. You will touch something grounded (alternator bracket, block, something) I promise, so disconnect the batteries when taking it off and wrap it with electrical tape for the test drive.

It just dawned on me you could wrap the wrench in electrical tape instead of disconnecting the batteries....I have never tried it.

If you pull the belt so the alternator is not even turning, you'll know if the alternator is generating noise that is being picked up by the adjacent wire harness.
 
Yea, I use a tiny 1/4" ratchet and shallow 10 to reduce the risk of arcing!

These VP trucks might be the death of me: my personal ride is acting up when my Redline box is on AND a truck I bought to "turn" went crazy today. It's going WOT if you touch the pedal at all. I've had this issue, it's just aggravating I have to spend more money on it.


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Vp44 trucks sure can drive a guy crazy sometimes. I have a 2002 in the shop now that is kicking my azz with no bus communications. I had a truck that had weird apps issues and would rev it's self up and some other issues. It turned out to be a bad alternator.
 
Ol Blue said:
Cheap band aids? I've read that several times trying not to take it as an insult....can't get there.

1 new VP, 1 new each sensor (MAP, IAT, Cam), 1 Timbo APPS, 3 different ECMs (none were new). Testing and diagnostics per everyone's suggestions with the exception of wrapping the wire loom at the firewall with a conductor where each end is run to the negative post of the battery on that side of the rig, plus others not suggested. Then onto discrete component filters with guesses at frequency, and currently back to hoping to find a loose pin somewhere.

If you have a specific suggestion, please say so, but with out the sarcasm please.

Sorry for the tangent Diesel Importer.
Click to expand...


I am not sure where you interpreted the word "cheap" as I said the "quick" fixes mostly cover-up bigger issues. No jab or sarcasm was intended.

Honestly, I would first try a new alternator that is verified to be low AC ripple as that seems to solve 90% of the problems with these trucks. The wire loom is easily back-fed into key system (ECM, PCM, APPS, VP) as they share grounding sources.

If that does not solve the issues, the option to replace the harness is on the table but that option is $$$ and time.

I had some weird behaviors with mine a few years ago and it turn out to be corrosion on two (2) of the ground leads. Once the corrosion was removed at those locations and all of the other locations checked/cleaned, the weird behavior went away.
 
Is there anything that lists all of the ground locations on these trucks to make sure one isn't missed?
 
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