Service Information Lacking

Dan from Buford Owner/Technician Posted   Latest  
Question
Driveability
1999 Dodge Ram 1500 Laramie 5.9L (Z) 4-spd (42RE)
Engine Will Rev To Limiter At Throttle Tip In

Calling any Dodge 5.9L Cummins experts. We have one that will rev to the limiter at throttle tip in. Once past tip in it will drive normally, no codes stored and no erratic data noted. Slow and light throttle input is needed to duplicate the concern. After scoping the APP and finding a lot of hash/erratic operation on the signal wire we replaced with a new APP from Geno's Garage. They have a cost effective replacement option vs the dealer. Symptom unchaged, further research is suggesting either a concern with the PCM commands to the FICM or the injection pump/FICM causing the concern. Both Alldata and Identifix are lacking in detailed info as to how these two modules communicate. 

Here is a link to the replacement APP: genosgarage​.​com/product/tps985…;

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Albin from Leavenworth

 

Diagnostician
 

Instead of testing the APP with a scope, test it with a scan tool. You need to be able to see what the PCM or ECM is seeing for the data. Many times the "cost effective replacements" are not a good choice.

This vehicle is using the VP44 pump, which is a case in its self. Over the years, I have encountered a lot of different driveability problems with this pump. Most all of these problems can be found by graphing the data from the engine control module. That being said, Bosch did not release much data to use.

On these vehicles, I use a Snap on scan tool to gather my data. The reason being, the Snap on will graph the data, which then can be uploaded to this site and others can take a look at it.

Many times, I hear "no problems seen in the data", which easily can be seen in data graphs.

+2

Dan from Buford

 

Owner/Technician
 

I don't disagree with the problems that can come with the cheaper parts. This case the OE APP was over $800, customer was willing to take a chance to save $600. And before we even started diagnostics I had a conversation with the customer about the VP44 being it was the original pump.

We were using a Verus which has great graphing features, but did not see any glitches with the APP operation or any other data at first look.

I would like to dig further into this, but the customer picked up yesterday declining any further diagnostics or repairs.

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Bill from Rosetown

 

Technician
 

Does the "hash" have any type of repeatable pattern, or is it just noise ? I am wondering if the fuel solenoid "noise" is observable in the pattern.

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Dan from Buford

 

Owner/Technician
 

No apparent pattern, but we did disable the alternator to make sure that was not the cause. No change there.

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Bill from Rosetown

 

Technician
 

You should see the fuel solenoid pattern (while its running) on the signal wire,even on a good one. Is this a standard or automatic transmission?

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Dan from Buford

 

Owner/Technician
 

It was an automatic. Unfortunately, the customer declined any further work and picked up yesterday; he felt the dealer was better equipped. Being there were already signs of him being more challenging than understanding I did not attempt to change his mind.

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Albin from Leavenworth

 

Diagnostician
 

At the dealer, it will first get a new APP installed. If that doesn't fix it, it will get a reman VP44 pump, if that doesn't fix it, it will get a reman ECM. Somewhere along the line, it will get all better.

-1

Dan from Buford

 

Owner/Technician
 

Albin, you are EXACTLY right and this is exactly what I communicated to the customer in that order. It was also explained that it is very rare for a dealer to posses and actually use any form of a lab scope, let alone thinking outside the box aka flow charts when it comes to diagnostics. The customer was already showing signs of being more challenging than understanding, mostly with selective hearing so I did not make an effort to change his mind.

+1

Martin from Burnaby

 

Instructor
 

Hi Dan. My long-time diesel background doesn't cover much time spent with the VP44 or any of the other injection systems used on the Cummins. However, with distributor injection pumps whether mechanically controlled or electronically, WOT when touching the loud pedal has historically been associated with an injection pump failure. I encountered my share of that symptom on about six or seven GM 6.5L diesels.

Scan data, graphing and basic testing will quickly rule out an APP issue, especially an idle to WOT concern. ECMs are usually pretty robust too and provided that power, grounds and other connections are intact and sound, it is very unlikely to be an ECM related concern.

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Andrew from Commack

 

Technician
 

There’s a TSB related to a fluctuating TCC caused by noise on the APPS/TPS signal wire.

dodgeram​.​info/tsb…

atraonline​.​com/gears/2006/200…​.​pdf

I’m not able to gauge whether your surge could be caused by a TCC issue from here. It sounds much worse than that. Dodge has reprogramming for this and the aftermarket has a wiring modification.

As far as service information Bosch has a lot of training on its engine and emissions systems at aviondemand​.​com

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