Hi everyone,

I am new to this forum. Have done some searching in threads but now found a solution to my problem.

I have a 2000 dodge ram van b2500 with a 5.2l v8. My problem is that it hesitates when it is luke warm. It starts and runs great when it is cold or hot, but it hesitates when it is lukewarm. What I mean with lukewarm is that the needle just starts to move till just before operating temperature.

I have no trouble codes. The sparkplugs and rotor cap were replaced last June when I had a misfire. In the last two weeks I replaced the wires and the coil. I also replaced the coolant temperature sensor thinking it was the problem. I cleaned the IAC valve and cannot find any vacuum leaks.

I took it in to a muffler repair shop to have the catalytic converter checked out with a heat gun. They said that it is working fine and not rattling so they did not think it was the problem. I do not want to replace it if I don't have to. It is too expensive.

My van does not have a egr valve, so that cannot be the problem.

Thanks for any help, Rien.

 

Does the cap have brass or aluminum contacts? If aluminum then replace with a brass contact cap.

If your fuel rail has a test port see what the fuel pressure is, if below 45 psi then that could be the problem.

Also another trick to try is one that member Stev was told one time to try "give it the finger". With the engine at operating temp you have the air cleaner removed and stick one finger down just behind the throttle plates where the air goes in for the IAC. You put your finger over that hole and start to choke off the air supply to it. This will cause the PCM to open the IAC all the way. If you can just try start to stall it a few times then totally plug the opening till the engine quits. Then leave the key on and disconnect the battery negative cable. With the key still on wait 5 minutes. Now turn off and remove the key. Reconnect the battery. Then turn the key on but not start the engine and wait for 10 seconds (this helps to reset the PCM and the IAC motor), then turn off the key wait 5 seconds then turn the key on and start the motor.

 

It could also be an O2 sensor. If it is, do NOT get the Bosch type. Those do not work well with the Magnum engines for our vans or trucks. And the connector is the wrong type on them anyways. The Delphi one works, but it's soooo expensive. The Denso I believe is the OEM and the NGK or whatever three character it is will work and is a good price.

 

Which one? The one with one wire going to it, or the one with two wires going to it?

 

Thanks for the tips so far everyone. I'll check it out next week when I have a change and let you know how it worked out.

Alloro: I am not sure. I thought there was only one coolant temperature sensor on my model. I changed the one right behind the alternator. I had to remove the alternator to get at it.

 

That one is for the gage. The other which is a two wire is to the left (or right when looking under the hood) of the thermostat housing.

 

Then that's likely the problem, you changed the wrong one.

 

I checked out the temp coolant sensor. My model only has one. The one that I changed had two wires on it. So I guess it does double duty.

A neighbor of mine had a snapon scantool. He let me borrow it. I found out that the upstream O2 sensor is running between 1.6 and 3 volt. I don't know why it is not setting a code, but I will get an O2 sensor tomorrow and let you know if that fixed it.

 

I put in a new upstream O2 sensor today and that fixed the problem. Thanks everyone for you input and suggestions

 

Thanks for the feedback on the O2 sensor. It really puzzles me as to why they don't set a code when the sensor is out of whack.