surging

[geraldg]

02 dodge 4x4 - Truck seems to unlock converter from around 50 to 60 mph. RPMs go up and down about 200 rpms. At times the throttle can make no difference if it is on the floor or not, the engine stays at the same rpm. We replaced the apps about 6 months ago and it seemed to cure the problem, but it is back.

[Mopar1973Man]

Any error codes? How is the battery connection on the passenger side? The PCM uses the ground right from the battery. How the alternator? A few have found that the alternator diode can fail causing noise in the power system which will cause this problem. You can go to most part houses and have you alternator tested on a bench for free but be sure to have the diodes checked! Some suggest adding a ground to the APPS sensor... But I don't suggest it... The fact remains that the truck ran all these years without and now needs wiring mods... Highly unlikely... But I would double check the connectors though... The engine ground for all the sensors and such is behind the starter and requires the starter to be pulled to inspect this ground.

[Prowelder]

I would reset the apps and see what happens. It could be a bad apps or a bad wire. Might want to pull the plug and put some dielectric grease inside of it just to make sure that isn't a problem!!

[Lucky2209]

I have been experiencing the same thing. I even replaced my APPS sensor witha timbo model and have had no luck :banghead: , I have not looked at the grounds yet though and have not tested the alternator. I guess that will be my next step. Very frustrating!! Maybe time to let go of my 98 and upgrade.

[Lucky2209]

Any error codes? How is the battery connection on the passenger side? The PCM uses the ground right from the battery. How the alternator? A few have found that the alternator diode can fail causing noise in the power system which will cause this problem. You can go to most part houses and have you alternator tested on a bench for free but be sure to have the diodes checked! Some suggest adding a ground to the APPS sensor... But I don't suggest it... The fact remains that the truck ran all these years without and now needs wiring mods... Highly unlikely... But I would double check the connectors though... The engine ground for all the sensors and such is behind the starter and requires the starter to be pulled to inspect this ground.

Thanks for the tip to check the ground, It was loose going into the clamp. I took them off both batteries and cleaned them up then greased them before putting them back on and haven't had any surging since. This also seemed to fix my long cranking before starting . Thanks for the knowledge.

[geraldg]

I appreciate all of the suggestions. The codes that were showing were the low voltage and the dreaded in jection pump. I did find that the ground cable was most of the problem. The surging has stopped and all other problems except that when I start the truck it runs up to about 10 miles and hour and you cannot accelerate from there. It seems the only cure is to cut the engine off and restart. It usually works fine from there. There are no codes shown.geraldg