I have a 99 4x2 ram with the 5.9L (360). It has started surging at idle during warm up (650 rpm to about 1300 rpm). It also surges when I'm doing about 90 km/h (about 200 - 300 rpm). Anyone with any ideas?

 

There are quite a few people who have minor surging on startup. I just haven't heard of it being that bad (650 rpm swing). Mind going into more detail on how it acts? Is it immediately after the truck starts, or does it happen a few minutes later? How long before it goes away. etc.. any extra specific details would be great.

Now onto the surging question when about 56mph. At that speed the torque coverter should be locked. If the converter is unlocking at relocking at that speed, that would give you your 200-300rpm movement that you are seeing. Causes for that could be as simple as a "noisy" tps sensor which is very easy to replace. I would pull the negative battery cable, install a new Throttle Position Sensor, and the battery back up and see if it acts differently.

Greg

 

Thanks for the response Greg. I was wondering about the TPS. I thought it might be causing the idle problem too. It only seems to do it in the morning and it starts after about a minute. This morning I drove it for about two minute and stopped and let it run while I ran inside for a few minute and when I came out it was reving up constantly. It usually goes away when I step on the gas but I have had to shut the truck off and turn it back on again sometimes. It will kick in while I'm backing out of the driveway sometimes causing me to jump on the brakes pretty hard. I hope this bit of information can help you out a bit more.

Brent

 

i had a bad tps do that one time. when cold it would surge up and down between 600-1500, back and forth, back and forth. when it got warmed up it would idle steady at 600.

replaced tps and it fixed it.

 

Thanks a lot. That is the direction I was going. I will give that a shot first and let you know how it works out.

 

Any luck bulldog? I have a 2000 ram 5.9 that is doing the exact same thing, except mine surges right after cold start up. Turn the truck off and back on and it is fine most of the time...

 

Well I pulled the airbox off and pulled all the sensors off of the throttle body. I cleaned the sensors that I could, cleaned what i could on the throttle body with out pulling it off and I resucured the air box. I had just had it in for an oil change before it all started and I think the air box wasn't on right but I can't be sure. Anyway after I did all that it stopped. The surging ont the freeway and the rough idle in the morning. Thanks for all that helped and pointed me in the right direction. If it comes back the first thing I wil do is change the TPS.