Engine/Transmission (1998.5 - 2002) Engine stumbling under acceleration

[JohnWilkins]

When accelerating between 1500 and 2000 RPM, especially in 2nd and 3rd gears truck "stumbles". Engine has never died and the problem is erratic. Sometimes it will act up constantly all day and occasionally it will be fine for a day. Exhibited the same symptoms in winter of 06 in 3rd gear when accelerating, but only a handful of times. Started acting up again a few months ago and seems to slowly be getting worse, occasionly in 1st and 4th gears it seems to lack power, but doesn't do the severe "stumbling" that it does in 2nd and 3rd. Also it doesn't fire up immediately when starting, acts like it has a little air in the lines like I've dealt with in the past, but this time it started when the stumbling started and I suspect the two may be caused by the same problem. I have also noticed that the truck smokes a while after it starts. I understand a little bit of white smoke because temperatures are commonly below zero for weeks up here, but it was in 30's other day and truck smoked for probably 10 to 15 minutes before clearing up. Truck acts the same whether it's parked in heated garage, plugged in outside, or started cold outside. Dealer had it for 8-10 days, returned it everytime with nice little "could not duplicate". Have extended warranty that injection pump would be covered under, but it ends in another 4000 miles. I have ordered APPS, Map sensor, and IAS to try and fix the "cheaper" things myself, but would appreciate any input as this is getting aggravating. I run power service additive religiously and have changed fuel filter. At 65000 miles the dealer replaced the injection pump and put the intake fuel pump replacement in. Truck is 01 5 speed with 104000 miles. I know not having fuel pressure gauge is a crime, but I do have edge attitude and an airdog waiting in boxes, but scared to put in until problems are fixed because of dealer warranty issues. Only codes thrown are for map sensor and rear diff speed sensor.

 

[ChrisWilliams]

That's some set of problems you have. First, check and fix what your codes are telling you, map sensor and rear diff speed sensor. The speed sensor can cause strange problems. I suspect you can perform some basic checks on these sensors with an Ohm meter. Also, check the connections at these sensors, spray with electrical contact cleaner and/or use a dab of di-electric grease, not too much, to make sure you are getting a good connection. Check out dodgeram.org for sensor ohm specs and/or get a shop manual from geno's and/or do a search on this site.



The white smoke is unburned fuel. Are your grid heaters working when you get the smoke, does your voltage gauge drop back? Check the resistance on your IAT sensor.



Does it stumble with the cruise control engaged? Maybe try to accelerate with the cruise control and see if it will stumble. The cruise control bypasses the APPS on a truck with a manual transmission.



Remember, all these sensors and the VP44 are controlled by the ECM. Check the connection to the ECM for corrosion as well.



I would do some more troubleshooting and replace the "cheap" sensors before buying the APPS or going further. Oh, and get a fuel pressure gauge ASAP.

 

[JohnWilkins]

I will change the map and speed sensors as soon as they arrive. Dumb question, but I assume the IAS controls the heater grid? And yes the voltage does fluctuate when the engine is warming up. Cruise control has never worked on this truck. I would like to fix it, if for no other reason than to test it like you recommend. Is there a fuse for the cruise that could have gone bad? Thanks for the reply.

 

[ROADWARRIOR]

I had an occasional stumbling problem with mine under load(boost). Turned out to be corrosion in the Edge Harness where it connects to the MAP sensor. The one pin was green. I was throwing a 027 code for the MAP. Edge sent me a new harness and all of my stumbling went away.



Try completely unhooking the edge box and see what happens.



Dan

 

[ChrisWilliams]

Actually the ECM controls the heaters, with input from the IAT sensor. It also controls the cruise control. You might go ahead and replace the IAT as well. While doing this, check all connections in the wiring harness, especially to the ECM and all sensors. Hopefully, you have a bad connection. The speed sensor could be part of your cruise control problem. All your fuses are either on the left side of the dash at the drivers door or in the big fuse panel behind the driver's side battery. It wouldn't hurt to check them all, but I doubt your problem is a fuse.



Remember, you need a 1 1/4 deep socket for the MAP sensor and a 13/16 deep socket for the IAT.

 

[ChrisWilliams]

BTW, fill out your signature so we know what mods you currently have on your truck.

 

[JohnWilkins]

Dan, I have the edge juice attitude but have never installed it, but the map sensor area could be at fault with a corrosion issue like you said



Chris, signature is updated.

 

[JohnWilkins]

Put in APPS, IAT, MAP, and Speed sensors. Map cured the problem. I don't know which was worse- the dealer not being able to identify the 0236 code or me taking the truck to them in the first place.

 

[Diese1nut]

I got an email from the guy that bought my 01 and he had a similiar problem. The truck accually quit a few times.

He found that when he tapped on the power distrubution box it would cut out on him. He found it to be the #6 fuse - engine. He replaced it and no more skip or problem.