[Bgcoop8784]

First off thanks before hand, and I've searched from top to bottom for this same issue with no luck. The problem is that when I first crank the truck, I have perfect throttle response for about 30secs to a minute, then all of a sudden, almost nothing. The truck will throttle up, but its really slow almost like its in a limp mode. If I turn the ignition off and back on it will work perfect again for about 30 seconds and then I lose throttle again. Problem is sometimes when the truck cranks up(could be the first time, or after I've restarted it with limp pedal), the throttle response will not go away, and I can drive the truck around with no issues at all. Little info on the truck and what its doing. When I got the 2000 dodge 3500 nv4500 cab and chassis, it had a P-Pump converted 5.9 fully built for pulling. I bought the truck not the engine, so I pulled the engine and replaced with a stock 5.9 out of a wrecked 2000 3500 that was running fine even after the wreck. Has a new vp44, new map sensor, and new apps that I recalibrated. All this was replaced before I started this engine in this truck the first time. Fass 250 titanium with new filters with right under 20lbs of fuel pressure(its a 100 psi glowshift gauge so right under 20 is best i can say). I know both battery grounds are good from the battery to the block and on the list of grounds I've seen, all of them are connected. (I'm surprised that there is not a ground from block to the frame, but I may add one.) The truck has thrown no codes and has no check engine or other error lights on whatsoever. Any suggestions?

 

[afterburn549]

Most of these truck's problems is the grounds. BTDT
There is a ground to the frame, driver's side in front. outside of frame EZ to see
It is a pee-pour one as they use a nut plate for the fastener.
The best cure for these is to redo all the grounds and weld bolts or studs to the frame for the grounds to be fastened to.
If you peruse these threads you will find a plethora of problems with mostly the same answers that fixed them.

 

[Bgcoop8784]

Thank you for the reply. I’m going to go through and double check all the grounds tonight. I put them all on this engine myself and made sure the connection cleaned/sanded all the connection points. I viewed the thread that shows all the ground connections, so I’ll double check to see if I may have missed one. I’m almost wondering if maybe the map sensor that I put in might be faulty. It was only around $40 off of Amazon so I feel as though that might be the culprit now that I see the others online are $120+

 

[afterburn549]

To make these things work, if they have seen ANY salt,
you need to provide an actual wire path to the Neg side of the battery and not rely on bodywork for the ground system
Also
The ends have to be cut off back to fresh wire or better yet replace with tinned wire and ends .
As it all will be green and pussie-like gangrene and not conducive at all.

 

[bigfish95971]

What year is engine? Did you pull codes with a scan tool or the key? Search here "defueling" or "de-fueling" and on google. or with mopar1973man,

 

[Bgcoop8784]

What year is engine? Did you pull codes with a scan tool or the key? Search here "defueling" or "de-fueling" and on google. or with mopar1973man,

The engine came out of a 2000. This truck is a 2000, but the engine I pulled from the truck was a 2001 styled newer engine p-pump conversion. I’m almost wondering if the ECM that was in my truck was a 2001 ECM, seeing how it was only being used on the other engine to run gauges, I was hoping it was the original ECM to the truck and not that engine that I pulled out. I’ll search it in a few mins. It’s for sure something electrical and not the vp44. Even though the vp44 is new, we tested the vp44 on another 99 truck with same lift pump just to be sure and everything was fine.

 

[Bgcoop8784]

What year is engine? Did you pull codes with a scan tool or the key? Search here "defueling" or "de-fueling" and on google. or with mopar1973man,

also, I have not pulled codes yet, I was hoping to get a check engine light to be sure it threw a code first. Will it throw a code without giving me a check engine light or some type of light?

 

[bigfish95971]

Don't wait for CEL. You have to figure out what you have. ECM runs your engine, it is not used for much, If anything, on P-pump. Get the part number off of the current ECM. I can tell which on it is for. Remember ECM is on Block and PCM is on firewall. No, the 01 ECM will nor run the 2000 VP.

 

[Bgcoop8784]

Don't wait for CEL. You have to figure out what you have. ECM runs your engine, it is not used for much, If anything, on P-pump. Get the part number off of the current ECM. I can tell which on it is for. Remember ECM is on Block and PCM is on firewall. No, the 01 ECM will nor run the 2000 VP.

I'll try to find a part # on it tomorrow. The PCM is for sure the one that came on this 2000 truck. I thought the ECM was also, but after I got the engine running and started trying to diagnose this issue, i noticed the p pump converted engine that I pulled from this truck is the newer (2000.5-2002) block. So it has me second guessing the ECM. Like i said, when I first started this after the swap, it fired up and ran perfect, got the hood and bumper bolted on, and it went to limp pedal after a minute or so. fired it up again and it ran perfect, drove it around for a half hour or so, parked it, fired it up an hour later, it drove perfect to my house from the shop. The next day i fired it up, it was fine, started backing down the driveway and limp mode again. I'll check part numbers tomorrow and double check the grounds again. I have access to a smarty touch also, its already vin locked to another truck, so I'll have to see if it will read codes on my truck without having to buy another vin unlock code from them.

 

[bigfish95971]

What year is the block presently in the truck? The PN is on a tag on the ECM, not sure if front or back. It will have PN, SN, idle Voltage, maybe one more thing.

 

[bigfish95971]

Ps. there is no such thing as "limp mode" only some kind of failure or mechanic failure.

 

[Bgcoop8784]

Don't wait for CEL. You have to figure out what you have. ECM runs your engine, it is not used for much, If anything, on P-pump. Get the part number off of the current ECM. I can tell which on it is for. Remember ECM is on Block and PCM is on firewall. No, the 01 ECM will nor run the 2000 VP.

I'll try to find a part # on it tomorrow. The PCM is for sure the one that came on this 2000 truck. I thought the ECM was also, but after I got the engine running and started trying to diagnose this issue, i noticed the p pump converted engine that I pulled from this truck is the newer (2000.5-2002) block. So it has me second guessing the ECM. Like i said, when I first started this after the swap, it fired up and ran perfect, got the hood and bumper bolted on, and it went to limp pedal after a minute or so. fired it up again and it ran perfect, drove it around for a half hour or so, parked it, fired it up an hour later, it drove perfect to my house from the shop. The next day i fired it up, it was fine, started backing down the driveway and limp mode again. I'll check part numbers tomorrow and double check the grounds again. I have access to a smarty touch also, its already vin locked to another truck, so I'll have to see if it will read codes on my truck without having to buy another vin unlock code from them.

Ps. there is no such thing as "limp mode" only some kind of failure or mechanic failure.

yeah I know, but easiest way that i know how to explain it, lol. It's not dead pedal, its more like after a minute or so it goes to extremely slow throttle response instantly. I can rev the engine once and it will be great, the next press, she takes her time trying to throttle up and has no power. Thank you again for responding! I'll get more numbers off the block and ECM tomorrow in the daylight. I don't know much at all about the whole vp44 engine years, so I'm researching all i can before asking dumb or repeated questions.

 

[bigfish95971]

It sounds a lot like what I have heard defueling sounds like, being right after start that way, but I am not sure cause I have never had it. You can buy a cheap universal OBDII scan tool for under 50 bucks. Did you do the conversion or did you buy the truck that way?

 

[Bgcoop8784]

I did the conversion, the ECM PN is 3946242, engine numbers are family: XCEXH0359BAM No: 56595079

 

[bigfish95971]

That should the correct PN for a 2000, not 99 or 01. 2000 is one that should have and use the crank sensor though. If you have a correctly operating Wait to start light light and no bad ECM code it should be fine. It does not work on a 01-02 block. Pull codes , looking toward a VP.

 

[Bgcoop8784]

I changed the MAP sensor today, went back and double checked and cleaned ground contacts. It ran fine. I took it on two trips about 30 mins each. After it sat and cooled down, it did the limp pedal thing again, until it warmed up, and then it was fine. I'll have to get a code reader or find someone with one around here and pull the codes next. The VP44 is brand new, its never been ran other than to test it on another truck and it was fine.

 

[Bgcoop8784]

Only codes being thrown are P0216 and P0380. If the engine warms up, it will drive fine, if its cold it will run fine for less than a minute and go to a limp pedal/slow throttle response, but not a dead pedal. Once it warms up a little, I can turn it off and crank it back up, and it will be fine to drive and will not mess up again no matter how many times i crank it, till it cools down. Any ideas?

 

[Bgcoop8784]

I will say that the I.O.D. fuse was blown, took me a few mins to figure out why I had no power to my OBDII plug. Replaced it and the reader hooked up fine.

 

[afterburn549]

I will gues you moved the wiring around enough to make a ground work better.
look at the right front top of shock , lots of them wear a hole on the harness right there.

 

[Bgcoop8784]

I will gues you moved the wiring around enough to make a ground work better.
look at the right front top of shock , lots of them wear a hole on the harness right there.

I removed the grounds and cleaned all connections and made sure there was no corrosion between the wire and the crimp/green wires, replaced a couple of terminals. No holes in the harnesses that i could see, I inspected all the ones going to the engine when I did the swap, and now its only doing this when the engine is cold.