• NAXJA is having its 18th annual March Membership Drive!!!
    Everyone who joins or renews during March will be entered into a drawing!
    More Information - Join/Renew
  • Welcome to the new NAXJA Forum! If your password does not work, please use "Forgot your password?" link on the log-in page. Please feel free to reach out to [email protected] if we can provide any assistance.

Fuel Mixture Problems

360-gpn

NAXJA Forum User
Location
TX
I just had my 4.0 rebuilt, We did everything from oil pan up to heads. The build was the same as putting in a long block. The only Mod we made was installing an Extreme 4x4 Cam (that is specific for this engine build) from CompCams. When I agreed to the upgrade I was told that this mod would be the only addition, and that it would give me more low end torque. Now we can't get the fuel mixture right. My mech. added a map sensor adjuster that he built, and we've gone through 3 TPS's. We are now waiting for a mopar TPS to see if that makes a difference.

We could not get the TPS to adjust, no matter where we set it the voltages remained the same. We have checked all vacuum lines, and connections, and even tried a new battery.

When we first got the engine in the Jeep we had a real bad spit and sputter and backfire at any cruise speed, meaning at any middle range. Then when I replaced the TPS it took care of part of that problem, but then I had no high gear or passing gear. The tranny is auto, and we hadn't had any problem with it what so ever.

Has anyone done this upgrade, or had these types of issues that they might shed some light? We've talked to CompCams and this cam, from what they say "is not a big enough change to cause any issues". Thanks for any guidance. It's been a month, and I'd like to have this for next weekends run. Terry
 
The obvious question is timing, is the alt in correctly?

Did the intake manifold and fuel system stay intact during the rebuild? I.e. you didn't unbolt everything from the IM?

You seem to be running in open loop or limp mode, which indicates a bad sensor, such as 02. Have you checked resistance on your o2?
 
It could very well be a sensor problem. I would however look at the timing. Check one more time the cam shaft timing. The other thing could be the distributor. Is it indexed properly? It could be off one teeth.
 
It could very well be a sensor problem. I would however look at the timing. Check one more time the cam shaft timing. The other thing could be the distributor. Is it indexed properly? It could be off one teeth.

Exactly, the cam selection has nothing to do with his symptoms. That's a very mild upgrade cam.
 
Back
Top