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trreed

VP Issues

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Ok guys, I'm lost with this issue.  Every now and then (very, very random issue) the truck will die when I push the clutch in and give me codes P1691, P0121, and P1693.  Here's where it gets weird.  Sometimes, the truck will rev up to 2k rpm by itself and die, giving me all three codes listed above.  Other times, it will just die, and only give me the P1691 and P1693 codes.  And then, it has been known to rev up by itself when I am shifting, but when I complete the shift, it starts acting normally again.  

Every time this happens, after about 1-3 minutes max with the key off, the truck will reset itself and start right up.  Until then, you can turn it over but it will not fire.

I've had three VP44's on my truck with the same symptoms.

I have just replaced the APPS with a Timbo unit.

I have switched the VP relay with the horn relay

AC Noise is .028-.03 at the alternator, and negligible at the battery.

This issue has been going on for about a month now, and it is VERY random.  Like it can happen twice in a day or go weeks without happening.  

 

I have yet to pull apart the wiring harness to see if there's a shorted wire, but based on how the truck resets itself when the key is turned off and is sitting still, I don't think it's a physical wiring issue.  What do you guys think the likelyhood of a dead ECM is? The WTS light comes on right away, and the fuel pump bumps itself as soon as the key is turned on.  

Edited by trreed

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Seem like your going to be replacing a VP44... The way the error code reads. 

 

1 hour ago, trreed said:

I have yet to pull apart the wiring harness to see if there's a shorted wire, but based on how the truck resets itself when the key is turned off and is sitting still, I don't think it's a physical wiring issue.

 

All you have to do is ohm from one end to the other. So VP44 to the ECM. Then while your ohm testing from end to end do an extra step of wire to ground and see if it report infinite ohms if so there are no shorts to ground. 

 

1 hour ago, trreed said:

 What do you guys think the likelyhood of a dead ECM is?

 

I kind of doubt the ECM is bad being the WTS is popping right on instantly and all other functions appear good. The P1691 is a PSG issue from what I understand. I think it's a typo in the document saying PCM because PCM has no connection on the fueling system at all.

 

The P0121 code is a APPS issue. 

Basically the APPS voltage is most likely too high during the IDLE position of the validation switch causing this error. Need to verify the APPS voltage adjustment make sure your bottomed out and adding an extra 1/2 turn to the stop screw.

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But these issues have persisted through three VP's (one brand new with 500 miles) and a new APPS.  I'll double check the APPS voltage, but i'm pretty sure I got that set right.

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Quote

Fuel injection pump controller calibration is monitored with ignition on engine off and with engine running and no CAN BUS errors reported. DTC may be set when PSG fuel injector pump controller and ECM RPM are mismatched or fuel commanded does not equal amount fueled.

 

So then I would be looking at cam sensor being it need to verify the engine RPM to VP44 RPM on the PSG. The fuel amount commanded or fuel amount you'll be able to see with the Quadzilla VP44 fuel message. So we need to look at the tachometer signal and cam signal would be my next thought. 

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I've collected two data logs of me manually killing the truck, while leaving the turbo timer on so the Quad can collect data.  

First data log is me physically unplugging the VP44.  The fun part starts on Line 4594.  Notice how the Quad is still reading "idle" RPM and the ECM is still fueling despite the truck being off. 

Quad unplug VP.csv

Then in the second data log, I purposely stalled the truck.  This starts at Line 10643.  This time, everything shut off and the Quad reports no "idle" rpm or fueling.  

Quad Killed Truck.csv

Thoughts?

 

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Once the ecm data stream stops the variables for rpm or temp etc are never updated so you will see the last value.   

 

 

So the ecm in the first set is confused and not sending data thus the Quadzilla is not getting data and not updating the screen. 

 

 

Kinda like

 

If ( RPM data update = T)

{

update rpm data

}

else

{

Don't update rpm

}

 

 

If I were you I would wire up 2 led test lights for the injection pump relay. 

 

1 on the incoming power source and one on the outgoing power source.  Drive around and see if the LED's stay on when you have issues. 

 

 

I am wondering if you have an upline power issue.

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That make sense, but in the first data log, there is 9 seconds of the ECM updating the canbus and rpm data after the VP was unplugged.  Did it just take that long to realize that it was not running?

Edited by trreed

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More than likely yes,  

 

 

The ecm does it's damnedest to keep the engine running so you will see odd stuff.

 

Edited by Me78569

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8 hours ago, jlbayes said:

Ppump it. Solve problem. Profit. :popcorn:

I tried to tell him...

F the ECM. All it needs to do is read the sensors and you're good. 

There was a full kit on FB for 2K, including the pump. Should have jumped on it. 

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What credit cards with interest free for X amount of time are for. :D

Edited by jlbayes

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21 hours ago, jlbayes said:

Ppump it. Solve problem. Profit. :popcorn:

You have to change cam too don't you? I'm at the age where when if one little screw is lost I won't sleep anymore thinking I lost it in the gears

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On 4/20/2017 at 11:15 AM, JAG1 said:

You have to change cam too don't you? I'm at the age where when if one little screw is lost I won't sleep anymore thinking I lost it in the gears

 

On 4/20/2017 at 1:01 PM, trreed said:

You have to take the cam out to change the front case, but the cam itself can be used.

 

This. No cam change required. I'm still running a stock cam and it performs wonderfully.

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So I've narrowed my issue down to either the ECM or the Quadzilla.  I've collected a series of data logs where suddenly the RPM, CANBus, and a few other values get "stuck", i.e. the truck reports going from idle rpm at 800 to 2621 rpm instantly with no throttle input and the fueling message gets stuck as well.  

I've tried to get data logs of this issue when the quadzilla is actively tuning the truck and when the truck is on OEM tuning, but I have yet to have the issue to happen when the truck is on OEM tunes....  So i'm beginning to wonder if the processor in the Quad is getting tired or something in it is glitching and sticking... I have one more test to do to rule out the ECM, just gotta wait for the truck to act up.

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