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+
-
June's Cummins of the Month is now open for entries! SUMMER FUN
Limp or slow pedal response...sometimes. Need ideas please
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?
1 - 20 of 55 Posts
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.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?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,
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.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.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.
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.Ps. there is no such thing as "limp mode" only some kind of failure or mechanic failure.
I did the conversion, the ECM PN is 3946242, engine numbers are family: XCEXH0359BAM No: 56595079
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.
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?
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.
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.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.
Thanks for the help, have fun on the fishing trip. What sucks is this is a brand new vp44 that was bought last year sometime and never used, the truck it was bought for ended up having a MAP sensor failure. The other truck had a completely dead pedal, new map sensor was installed, didn't help, put this brand new vp44 pump on it, didn't help, put the old pump back on it and used all sensors out of known running truck, and it turned out being a faulty new map sensor the whole time. So if this is it, I bought a "brand new" VP44 pump that was a faulty rebuild and its out of warranty now.
I'm sorry, i haven't seen the hotwire test. I'll look it up now.I am senile and lost-did it pass the Hotwire test.?
From what i can tell, the hotwire test only makes sure that the vp44 is getting power to start and run the truck, is there another reason to do this test? The vp44 works and cranks every time. It revs up fine every time i crank it, but when engine is cold, it will have an extremely slow throttle response after a minute or so, when engine is warm, the throttle response never goes away and it runs and drives fine.I am senile and lost-did it pass the Hotwire test.?
My neighbor purchased it, I was there when it was put on his truck the first time, it was hardly ran at all on there before swapping it back out because it didn’t solve his issue. He started having dead pedal on his Cummins right after buying the truck that I’m building, so the vp44 was originally purchased for this truck is why he swapped back out when it didn’t change anything on his truck. Fuel pressure from lift pump is sitting right at 20psi. I’m going to cut the return spring on the fass a little today and get it down a few lbs.
I’m going to keep tinkering with it and go over all my connections and wiring before buying another VP44. After all, this truck had a p pump engine in it when I bought it from him, so with all the swapping that I had to do, there’s a good chance that I missed something small. I tried my best to research and replace any “know issue” sensors/pump and all before I even put the engine back in the cab. I have the live data tool now with screenshots for all the sensors. I’ll have to research a little to see what the “normal” reading for all of them and compare that to when it throws the code, Atleast I should be able to diagnose what’s not wrong, lol
Thank y’all again for the responses, I’ll do the hot wire test tonight if I have time and keep y’all updated.
I’m going to keep tinkering with it and go over all my connections and wiring before buying another VP44. After all, this truck had a p pump engine in it when I bought it from him, so with all the swapping that I had to do, there’s a good chance that I missed something small. I tried my best to research and replace any “know issue” sensors/pump and all before I even put the engine back in the cab. I have the live data tool now with screenshots for all the sensors. I’ll have to research a little to see what the “normal” reading for all of them and compare that to when it throws the code, Atleast I should be able to diagnose what’s not wrong, lol
Thank y’all again for the responses, I’ll do the hot wire test tonight if I have time and keep y’all updated.
Fuel pressure from the FASS lift pump is at 20lbs, I'm going to cut the spring to get it down a little more laterWas lift pump removed for P-pump and not put back on. Did you check fuel pressure yet?
I searched on here and a few others, it’s not too high, but from what I can gather, higher than normal fuel pressure causes th vp to return more fuel which adds more heat to the fuel, return spring on the vp is set to “14” so anything higher than 15 or so just gets returned. So I’m going to shoot for around the 17psi mark. I also have big lines running from the lift pump straight to the vp, so I’m showing almost no drop in pressure from idle to WOT. I don’t think this has anything to do with my issue, but might as well make things better while I work on my limp pedal issue.I think if that is too high for your truck it would cause hard/non start but not sure. Search here for high fuel pressure and VP44 fuel valve or something like that.
Thanks again, I'm trying my best to take every bit of advice that has been given. I was the person saying that I was going to lower my fuel pressure, I never argued that at all. Yes I do have the problem, and I'm glad there are people to help me with possible solutions. If this truck was a running VP44 truck that just started having an issue, I feel as though it would be an easier problem to solve. I will probably replace the VP pump this weekend with one off of a running truck just to see if that's the issue. The worst part is that I have to wait for the truck to be completely cold every time I change something or else it will run fine till the temperature drops.Sir,- you are the one having problems -all we can do is make some recommendations
These trucks become very hard starting with too much pressure.
10 lbs is purrfect .
For a given size of pipe, more pressure means just that, not more volume.
Do as yu wish
Something I noticed today, I'm not sure if this will help at all. I let the truck warm up, and cleared out all codes. The P0216 code still popped up after it ran for a minute or so, but the truck still ran fine. It didn't do the "limp pedal" issue. So i tried it again, same thing. It will still throw the 0216 code and run fine unless the engine is cold.I do not think it is your problem but It can be . At 20 lb+ or more on some VP's (kind of random) there is a valve in the VP that can shut down. Not really your symptoms I believe. No ore significant increas in heat any where. The the return system is meant to cool the VP purposely. Even at below 14lb there is an amout of return fuel from the VP and injectors in the head.
I can drive it like this, lol, but its a new(to me) build. I want to get it code free and no cold pedal issues. If if actually had dead pedal, i wouldn't mind just ordering a new VP44, but even cold I can drive it, it just has reduced power, pretty sure its something to do with the timing from the vp44. I am going to double check my vp44 keyway installation and go over all my grounds again this weekend. If i cant find the issue, I'll just swap the vp44 with one off a running truck to test it.I’ve been driving mine for 16 years with it throwing the p0216 code. Got used to the cold dead pedal issue cuz once it warms up it runs fine.
towing various trailers and never a failure in 16 years.
I reckon I’m just lucky eh??😎
1 - 20 of 55 Posts
Cummins Diesel Forum
A forum community dedicated to all things Cummins Diesel! Originally founded for owners and enthusiasts of Cummins powered Dodge pickups, the Cummins Forum has expanded to include ALL Cummins Engine applications! Come join the discussion about reviews, drivetrain swaps, turbos, modifications, classifieds, builds, troubleshooting, maintenance, and more!
Full Forum Listing
Top Contributors this Month
View All
the man in black
393 Replies
Jimmy N.
378 Replies
dieselenthusiast
315 Replies
