Engine/Transmission (1998.5 - 2002) What controls Fueling?

[kdw75]

I have the surging problem that just started out of the blue and I am wondering if anyone can tell me what items control fueling and timing that I should look at. So far I have checked the grounds and using a meter they all seem to be working well and the ECMs ground it working good, about 2 ohms resistance to the negative battery post. The Fuel Pump is a Reman with about 20,000 miles on it from Chrysler. I have replaced the ECM, APPS, IAT, MAP/Boost, Crank and ECT sensors so far. I have not replaced the Cam sensor or the VSS sensor and I am not sure if either of those could cause surging. I have also removed the TST box and wiring harness just to eliminate that.



Thanks,

Keith

 

[BillGotthelf]

What speeds, rpm and gear does the surging happen?

 

[kdw75]

It is mostly around 1500 and 2100 RPM. It is always a surge of power, never a loss of power. Usually lots of them off and on so it throws your forward and backward but just enough to be obnoxious, not enough to really throw you around like it is missing or anything. I have tried recalibrating the APPS by unhooking the batter for 30 min but didn't seem to help. Maybe I should try overnite. The powermax light helps you see what it is doing and even sitting still you can race the engine in neutral and when the surging happens the light flickers from dim to bright about 4 times a second until you change the RPM and when you let of the timing will noticeable change.

 

[BillGotthelf]

You still did not say what speed or gear you are in.

 

[kdw75]

See above I was editing my post. LOL Yeah, any gear any speed. Seems to be RPM dependant.

 

[BillGotthelf]

Sounds like the TPS or the APPS which I believe are the same thing. With everything you have changed it seems to point to that. Since it uses small voltage numbers (as little as . 02 volts) some minor voltage fluctuations could cause the surging.

 

[kdw75]

Yeah, but that was one of the things I changed. On mine it is the APPS according to dodge. $350 down the drain unless the wiring to it is messed up or something. The plug looked ok and had grease still on it. The only thing I have done is get someone with a code reader to monitor the voltage while it is acting up.

 

[ToolManTimTaylor]

KD how is that P Max Connection doing? More so does the PMAx2 pierce the pump wire? If so How do you have it tapped?

 

[Gary - K7GLD]

(sigh!)



Yet another "hesitation with no codes" problem...



Do a search on "hesitation with no codes" that will bring up that thread, and a number of others on the same subject - grab a cold drink and get ready to do LOTS of reading that will be informative, but provide NO real solution!



Just for the record, the 3rd generation trucks are having the SAME problems...

 

[kdw75]

Well, like I said, I have totally removed the PMax and and plugged the MAP in directly bypassing all of it's harness and still have the problem. I just hook it up so I can see the fuel light flicker for testing. It is one of the crappy scotchlock connectors but that shouldn't be able to affect me without the PMax hooked up right? God, unless water got in under the insulation on the pump wire it is on and corroded it or something. Ok, that may be a little far fetched.

 

[BillGotthelf]

The only way to monitor the APPS signal output is to go thru a code reader into a laptop that has a program to graph the voltage coming out of it. Like I said it does not take much voltage fluctuation to cause a surge condition or cause the TC on an auto to lock and unlock hundreds of times a second.

 

[Bob4x4]

You may have a hard time getting a scanner with a fast enough refresh rate to catch a flakey sensor,unless you can get the fluctuation consistantly.



Bob

 

[ToolManTimTaylor]

That's what i was getting at with the scotch loc. But you have taken the P Max out of the loop so there goes the theory. I have seen a few trucks with the Pump covers surge like mad due to a bad pump connection that would be very touchy (Studs strip and back out) and was wondering if that was the case here. Yeah it could be dreaded apps interference but it just sounds oh so familiar to me. BTW I Saw a HAPPI box on e bay.

 

[kdw75]

I wouldn't have two bad APPS though. So I guess it could be the wiring or plug to it.

 

[RKohn]

had mine cut out a couple times @ 70mph

Almost crapped my pants.



Finally figured out that one of the 50 things on my keyring got caught in the hole on the backside of the steering wheel and turned the ignition switch off.



Note to self - Put all that extra stuff on another keyring and toss it in the ashtray.

 

[Sticks]

As funky as this sounds, with the engine off and the key off, fully depress and release the throttle about 10 times rather fast. This clears up my surging for about three or four days. I am convinced that at least I have some goo that is causing the fluctuations in my sensor.

 

[BillGotthelf]

Key Ring shutoff-happens to me once in a great while while I'm turning. NOT FUN.

 

[JR2]

There is also the issue of stray voltage being induced into the APPS wiring. Ther is a member who makes a rewiring kit that moves all the APPS wiring away from all the other wires.



JR2

 

[BillGotthelf]

There is also a company that makes a small box that takes 15 minutes and eliminates the problems also. www.happibox.com

 

[kdw75]

Thanks for that link Bill. The fact that such a box is made makes me think this must be a common problem. Though I still wonder why the problem would just show up one day out of the blue.