Engine/Transmission (1998.5 - 2002) Can a VP44 fail and not flag a code?

[MHagen]

Can a VP44 fail and not flag a code? I just swapped in a 55 block out of a 2000 with low miles that had a nice shiney VP44 that says rebuild on the top. I figured Id run it assuming that it has to be better than my OE that has 182,000 miles on it. Ive got about 700 miles on the motor and all was fine but slowly Ive been losing power and running quieter. Now today it was missing under throttle. I have no codes.



Mike

 

[BFritz]

Yeah, it can fail without codes. . the codes will only show up if its an electrical failure, and if its mechanical it wont throw codes... (or so I've been told by numerous people) I just replaced mine and it didnt throw any codes.

 

[MHagen]

Anything else anybody might think I would want to check before swapping my old VP44 back on? Im just having a hard time beliving that My O. E. VP44 that I starved 3 times myself before getting my fass, outlasted a rebuilt one that appears to be new.



Mike

 

[BFritz]

What FP do you have going to the VP44? I'd crack the injector lines and crank the engine and see if your getting fuel to the engine. If there is fuel then I'd say the problem is somewhere else.



Good luck with it...

Brian

 

[MHagen]

What FP do you have going to the VP44?

FASS pushin 21psi at idle and 17 at wot. Also, I thought that trucks with weak VP44s started hard. This thing pops right off.

 

[Cummins724]

It could be a APPS sensor going bad... . I'd try that first.

 

[Batphreak]

Yeah, it can fail without codes. . the codes will only show up if its an electrical failure, and if its mechanical it wont throw codes... (or so I've been told by numerous people) I just replaced mine and it didnt throw any codes.

Other way around from what I've read/heard. If hte electronics fail sometimes it just doesn't know its failing. When the mechanical portion fails it can't hit its timing right, that sets P0216.

You can check the APPS (hook up to the wire at the PCM with a multimeter, just search on the web for instructions) if it runs up and down nice and smooth it's gonna be the VP. Mine has been giving dead pedal at times for just about a year with no codes set, getting a new VP this coming Monday.

 

[socalmat]

Many have found that correcting the output voltage from the APPS sent to the PCM has increased the throttle response, and boost. This calibration also adjusts the APPS for wear.



Instructions:



Tools: Digital Volt Meter, T-20 Torx bit, #1 phillips, 10mm socket



With the key on, engine off you need to probe the APPS wire to see where the voltage is currently set at.

The best location to probe the wire is on the PCM (Power Control Module) which is located on the passenger firewall behind the air intake.

You want the C1 connector, this is the connector closest to the engine

You want the orange wire with a dark blue tracer which is pin #23 (Please use a suitable backprobing adapter for your meter lead, do not pierce the insulation as this can lead to water intrustion/corrosion. )

Voltage should be somewhere around 0. 5 volts,

At this point the voltage reading does not matter, it just has to be accurately written down for later reference



TURN THE IGNITION OFF ON THE TRUCK



Remove the black plastic cover off of your APPS. There are two plastic screws. One on the top and one on the front facing the radiator. It takes a little prying to pull it off.



Undo the 6-10mm bolts that hold the bracketry in place but DO NOT REMOVE THE CABLES!!



You will notice the APPS is on the back of the bracketry that you just removed, it is held in place by 2-T20 torx bit screws. These screws have a little bit of locktite on them so make sure you have a good socket and gently give a little tap with a hammer before attempting to loosen. Be very careful because these screws strip VERY easily and you only get one shot at them (VERY VERY VERY IMPORTANT; They are VERY tight).



On the APPS you will find a white tag that gives you the information on what the APPS voltage should be.

After loosening the screws (do not remove) you can rotate the APPS clockwise or counter clockwise to get the adjustment (towards the front of the truck increases voltage and towards the rear of the truck decreases voltage)

The reading you took at the beginning of the process on pin #23 should match the white tag on your APPS. If it doesn't the adjust accordingly.

 

[MHagen]

I replaced the apps about 18K ago, Id assume thats good. I drove around 200 miles and it didnt do it at all today. Damn thing ran like a race car all day. Even got myself a speeding ticket!#@$%!



I was wondering if the map sensor (I think thats what its called) could be sticking. I didnt swap that out when I did the motor swap. Im going to swap it tomorrow just for the heck of it. Thanks for the info on how to check the apps. When my apps failed it did flag a code though and it acted very different than this. When my apps failed it had a blank spot in the throttle. Yesterday it felt like random misfires.



Im not convinced the VP44 is bad. Every time something has gone wrong with my truck the VP44 is the first thing everbody said was wrong. So far everybody has been wrong. Im not saying that its not possible today but Id like to diagnos the problem properly. Thanks for all the tips guys.



Mike

 

[BTRBILT]

When my Vp-44 died it didn't leave any codes. At first it would stumble a little, but only once or twice a week. Then right before it quit for good, it would start and idle, but would not drive. Then the next day it was normal and drive with no hesitation at all. Then a week later same thing ,won't start.



I took it to the dealer, tech said there was nothing wrong . It set no codes and he drove it about 20 miles with no signs of any trouble. So the tech goes in the shop to pull it out, and it won't start. They replaced the injection pump the next day.

 

[LowFly]

From what i have seen when the VP goes out without codes are the hard/no start issues. Like cracking injectors lines or haveing to use either to get it started. Most everything else i have seen there was the P-0216 code... ... and others..... Always read codes with a scan tool. The Key trick doesnt always show all the codes from what i have see... ... . if you truck can even do the key trick... .

 

[timbo]

I just replaced my VP because it was dead petalling, and smoking upon start-up, then snap out of it and GO! It never threw a single code.

 

[johncameron]

Can a VP44 fail and not flag a code? I just swapped in a 55 block out of a 2000 with low miles that had a nice shiney VP44 that says rebuild on the top. I figured Id run it assuming that it has to be better than my OE that has 182,000 miles on it. Ive got about 700 miles on the motor and all was fine but slowly Ive been losing power and running quieter. Now today it was missing under throttle. I have no codes. Mike

Mine just died and I was stuck on the side of the road without codes:{

 

[wtfd6]

the key trick reads the pcm codes not the ecm codes. thats is what the p1693 is for. it tells you the ecm has a code. or vice versa when using a scan tool.

 

[MHagen]

I found something interesting today. I unplugged the EZ from the factory harness Boost connection and it was green with corrosion. I cleaned it up and put some die electric grease on it. It was pretty bad, I wonder if that could be causeing improper readings and giving far too litte fuel. Its worth a shot. I will keep you guys posted on if it comes back.



Mike

 

[SnoKing]

the key trick reads the pcm codes not the ecm codes. thats is what the p1693 is for. it tells you the ecm has a code. or vice versa when using a scan tool.

I do not believe that is true. Mine goes thru the PCM codes (DTT cause a few) and then the ecm codes 0216 and 1693. SNOKING

 

[wtfd6]

I do not believe that is true. Mine goes thru the PCM codes (DTT cause a few) and then the ecm codes 0216 and 1693. SNOKING

Im not 100% sure.

 

[SnoKing]

Im not 100% sure.

Actually they both end in the 1693 saying the codes are set in the other module. SNOKING

 

[MHagen]

UPDATE



It did it again today so I hooked it up to the OTC scanner. I drove it around with the scanner hooked up and found that the MAP sensor had no change. I put in a new MAP and everything is rockin again. Oo. It must have been sticking.



Mike