Limited Pedal, VP problem?

[DIezl]

I was having an intermittent problem where the truck ran great for the first 15 min then after that I was having problems.
It was acting like it wont spool up, ill hit the pedal and it will be around 10 psi of boost and will just sit maintaining speed for awhile until the RPM's hit around 2k where the turbo lights then takes off.
Tried resetting my APPS.

I have no codes on my scanner or check engine light.
I have about 17psi fuel pressure and doesn't drop much at wot maybe to 15psi.
I had a boost leak and fixed it then the truck ran perfectly for about 4 days. I was still skeptical if that was it and unfortunately i was right.

The last two days it has came back and has been way worse. So now it will surge I guess you could call it, I'll just be lightly accelerating and it will sort of cut out or stutter this has only happened twice. But now it hits a certain rpm and just hangs there no matter how much more you press on the pedal. If I let off from that position it acts normal but if i press anymore further it will not rev up any higher or do anything. It will still gain speed just very slowly. Feels like it has no power at all.

I measured my AC voltage today and got .028, and ill add i haven't had the TC unlocking/locking problem happen to me. The more i read into this AC leakage i was really thinking maybe it is the alternator but now that i tested it its looking more toward the VP.

The VP was replaced about 30k miles ago by a previous owner so its hard for me to believe its gone bad but i know people have had even less life out of these pumps. Its been fed good fuel pressure and 2 smoke oil while Ive had it at least.

Is it the electronics on the pump? Maybe from the edge comp heating it too much?

Can i check anything else or any other ideas?

Thanks

[dripley]

 I am thinking you have a MAP sensor or associated wiring issue, it might even be the Comp itself. You can eliminate them Comp by disconnecting it. If it is still happening then it is not the Comp.

 I battled the same issue for a while. Started with surging and APPS codes with occasional MAP code. Swapped the APPS and no help. Then I tried swapping in my old MAP sensor. Well I broke it and put the other one back in. The surging disappeared. Fast forward and I started having the same issue you describe. Low power, slow accelaration and low boost. No smoke either. If you have a lot smoke with the symptoms I would suspect you have another boost leak some where. I also got a stray p0237 code sometimes but not always, most times no code.

 Anyway I have partially solved my problem and am 99% sure it is in the wiring. This is because the thing I have done is manipulate the wiring and it stopped. There is a 5v signal wire splice in the wiring harness just outside the ECM. It is for the MAP and oil pressure switch. I think that is where my problem lies but have not had the time to open it up and see. Might even be one the pins on the connector, I just don't know. The truck acted up again a little while back and I reached down and grabbed that part of the harness and gave it a squeeze and a wiggle problem gone again. 

 

Here is picture of it. This is a spare wiring harness I have.

 

 I cant gaurantee this is your issue but I also don't believe it is the VP.

 

If you have a way to monitor the MAP sensor while driving that would help. You could watch my sensor drop out when it act up.

Edited July 10, 2018 by dripley

[Mopar1973Man]

7 hours ago, DIezl said:

Is it the electronics on the pump?

 

If the PSG is damaged usually you'll have a P025x code or P1688, P1689. Once anything gets out a range just slightly the code is instantly tripped. If there is any electronics fault on the PSG typically the code is thrown.

 

7 hours ago, DIezl said:

Maybe from the edge comp heating it too much?

 

Myth. My last VP44 ran 243k miles with both an Edge Comp for ten years and the switched to Quadzilla for 2 more years. Being I running the Quadzilla now I can tell you that fuel temperature and IAT temperature are typically within about 5 degrees of each other. Fuel temp wise I typically never get much over 130*F with summer temperatures over 100*F. The whole heat soak thing is a myth too. It does not rise up after the key is turned off and fuel pump stops.

 

As for limited pedal typically that is an ECM problem. 

[JAG1]

Mopar1973Man, is it possible it could also be a worn or intermittent throttle position sensor? 

[Mopar1973Man]

41 minutes ago, JAG1 said:

Mopar1973Man, is it possible it could also be a worn or intermittent throttle position sensor? 

 

Typically no because even if the APPS gets out of range it will throw a P0122 or P0123 code and dead pedal completely. This can be check by monitoring the TPS on a live data OBDII tool. 

 

Limited pedal is a different creature. Basically, you have some throttle but you never are able to exceed a level of engine load. For example WOT (100% TPS) only produces 60% engine load tops. Where dead pedal produces 0% engine load during the event. (TPS either 0% or 100%) Both values can be monitored at the same time engine load and TPS values. 

[DIezl]

Thanks for the reply's, I will try taking off the edge tonight. Sucks i haven't got a code to even go off of yet.

Is there anyway to diagnose a bad ecm? and is the .028 vac i got anything to worry about? I noticed one of the previous owners had put aluminum foil over the wire going by the alternator didnt realize it wasnt factory until i read the AC article on this site.

 

[DIezl]

So I unhooked the edge connections and plugged the stock plug for the map sensor back in and it ran fine no problems. So i stopped somewhere and plugged the edge back in and drove it back home and it ran perfect as well. I really dont know what to think.

[dripley]

That is exactly what happened to me. It started with trying to swap the MAP sensor. Ended up with the same sensor but the truck ran like it should. So the only thing i messed with was essentially the wiring harness. But the problem was solved. That why I am pretty sure it is in the wiring harness at the MAP sensor. but thru that process I know my hands got on the harness at the ECM also.  At least I am convinced that is where my issue lies. I am thinking the 5v signal splice near the the ECM. Just wont know for sure until I get some spare time.

Edited July 11, 2018 by dripley

[DIezl]

Yeah it does sound very similar. I tested my APPS according to a write up by cummins i found on another forum and it passed.

Also, i had a decent scanner with me today and when i pulled the edge wiring off I tried running live data I didnt see the map sensor move off 30.1 inHg(i believe that was the units). When i plugged the edge back in the value was moving into the twenties when accelerating i believe i didnt pay as much attention to it as i probably should have, Could this mean bad map sensor?

Maybe ill try and see if i have 5v at the plug and a good ground, clean the connections and go from there.

[dripley]

I monitored my MAP with my scan gauge. They read them strangely, I idle around 26 psi and max I ever see is 39 ps. This is quite normal for the scan gauge but don't why. Any way when the low power issue would happen the reading would drop to 14.6 psi and just stay there. Then when the power would come back the scan gauge would back to it's normal readings.

 Mine also started doing this sporadically any time. I got the engine load above 40% or so. The higher the gear the easier it happened. It would show on the scan every so often due to the SG's slow refresh rate. It acted very much like a loose wire. A manipulation of wiring harness stopped it. Mine is starting to do this again so a manipulation of harness in order again. It this fixes it again I am certain it is in the harness and not the sensor. 

 The MAP also shares a spliced ground with several other sensors very near the signal wire splice so it could be in the ground. My finger is on the splice. 

[Dieselfuture]

6 hours ago, dripley said:

My finger is on the splice

I'm thinking I got to find time and address that splice myself,  then I know it will eliminate another weak point. 

[dripley]

15 minutes ago, Dieselfuture said:

I'm thinking I got to find time and address that splice myself,  then I know it will eliminate another weak point. 

I am putting my money on the 5v signal splice more than the ground splice but it could be either. Something looks weird about it in the 1st picture posted.

[DIezl]

So drove the truck again after work and it ran normal with the edge plugged in. I still feel like it will do this again and probably at the worst time possible, I don't know if i should replace the map sensor or wait.

Dripley, what do you plan on doing if your 5v splice is faulty?

[dripley]

6 hours ago, DIezl said:

So drove the truck again after work and it ran normal with the edge plugged in. I still feel like it will do this again and probably at the worst time possible, I don't know if i should replace the map sensor or wait.

Dripley, what do you plan on doing if your 5v splice is faulty?

Re splice it. That part should be simple. Getting the time is the hard part for me. I don't like getting into things like this with a small time window and time at home this past 3 months has been tough to come by. I will be done and gone from Maryland in 2 weeks and much closer to home for a while.

 

 If the problem is in the wiring, replacing the MAP sensor wont fix it. If it starts doing it again manipulate the harness and see if it stops. 

[DIezl]

Well all was good for over a month I don't drive this thing everyday but it has been fine since my last post until yesterday when i was coming home from a job interview about an hour away. Truck ran great on the way up there and about half way home when i go to merge on the interstate my power is gone and it feels just like it did before.

I also kinda noticed at lockup a little shutter i think at least never felt that before.

So dripley have any problems with your truck lately?

[dripley]

 Yes and no. I resealed my hydro boost a couple weeks back and when i took for a test drive my sensor had dropped out completely again. I went back to the house and checked my booster for leaks and all was good there. I reached in and gave the wiring a good squeeze and drove back up the road and no help. So I go back and started checking for codes, had a couple no big deal. I have 3 splices in my harness near rhe ECM, thats a whole other story there. I just did a visual and tugged on the wires to see if they were not coming apart but all seemed well with them.

 I get back in the cab and fire it off. The next thing i know the temp gauge pegs and cel is lit. Check for codes again and I got 8 or 9. Low and high voltage codes on sensors and what not. This along with the temp gauge pegged I am having dejavu one an ECM fried. Thats exactly what happened when I lost mine 8 or 9 years ago.

 So I get back under the hood and removed my fuel filter canister so I can have better access to the ECM and harness and really dig into those splices. It was diring this process that I found i have a 4th splice that I had forgotten about. I redid the other 3 several years ago but missed this one and when I went to tug on it, it just came apart easily. Turns out this wire is the main 5v supply to most of the sensors. Long story short I got out the solder and soldered the connection, cleared the codes and went for a quick drive and all is well. The weird thing to me is the MAP sensor gets its 5v from different pin on the ECM so I am not sure why i was having the MAP issues. Someone smarter than me will have to help with that.

 I have had no MAP issues for the past 3 weeks but my engine surging is back, though very intermittant. It started about a week and half ago. It would seem that have more to do.

 

 @Mopar1973Man I seem to remember someone being suspect of those splices a good while back. That 4th was tucked back into the other wires enough that lost track of it. So I had a little Crow for dinner that night.

 

 

 

 

 

[DIezl]

Well at least some good news there, you think the surging is a separate problem from the splice?

Ill have to check my splices i guess, yours were bad from the factory?

Drove the truck tonight was fine for awhile then started not having any power again so i pulled over and unhooked the edge all was good with no comp for at least an hour of cruising the backroads. So i pull over again and put the comp back on and runs perfect on the way back home. Was thinking it was going to be the comp but not sure what to think anymore or try. I will check my splices i guess.

 

[dripley]

The splices i am speaking of are not factory.  I got some missguided advice many years ago  when my ECM died and cut some wires for testing. There is however a ground splice in the harness for the sensors. Whether that has anything to do with it, i dont know. The surging stopped a few months ago after messing with the map sensor and hareness in that area. I guess iam back to square one for now.

Edited August 24, 2018 by dripley

[Mopar1973Man]

Hence why he's got a second wiring loom and still has taken the time to install the new loom. 

 

[dripley]

36 minutes ago, Mopar1973Man said:

Hence why he's got a second wiring loom and still has taken the time to install the new loom. 

 

Time is a precious comodity when you are on the road as much as me. I know you can understand that. On a good weekend while in Maryland about 46 hours of time there and some weekends not home at all.

 

Then when you put Ripley+wiring+electrical trouble shooting in the same sentence, that just spells trouble. Now after doing @W-T's ground mod and seeing how simple that was, it gives me greater confidence. Just need to check the harness out better.