I've searched threads for a couple weeks and tried many things but I might be at a loss on how to fix this. 2001 Limited, put in a new stroker and upon startup it pops and stumbles a bit then the tach heads toward redline and I have to shut it down quick. In the short time it has run at each attempt the plugs show very rich condition which explains some backfiring in the exhaust I believe. No codes, although one did come up at first for the MAP and I replaced that along with a Mopar TPS and used Standard brand MAP sensor and IAC. All three replaced after reading similar posts about an elevated idle speed, although this isn't just elevated idle, if I let it go it the tach needle would peg out. I didn't mind throwing a few parts at it because spending time in the garage is relaxing to me and I was able to teach my teenagers what the parts do and how the systems work.

I hear no vacuum leaks and dread removing the intake manifold again to check to see if I can tell if it was sealing well (I broke my right clavicle last week) but maybe that's my next move. I am 95% confident the cam position sensor is in correctly. Any other ideas? Need to get it to run so I can properly break it in. Has what appears to be original injectors and o2 sensors. Thanks in advance.

 

I have heard many times on here that there are some locating lugs for the inlet manifold and it always seems to be that one isn't located properly even if it all looks correct. Hopefully someone else can chime in with some more information.

 

boxburn is correct. 9 out of 10 times this symptom comes up on the forum it is the intake manifold sitting up on the rear locating dowel instead of flush against the mating surface.

If you block off the top of the throttle body, and the problem still happens, it's almost certainly the problem.

In order to have high RPMs there must be air getting in. Even your computer can't make the RPMs increase significantly without letting more air in via the IAC.

 

I believe they nailed it.

 

Thanks Jordan96xj and boxburn. I’ll give it another shot.

 

that's what you'll find.

 

You all were right once again. Looked it over and didn’t appear it was on top of the locating dowel but clearly not sealed. Felpro gasket was deteriorated at each intake port due to fuel which surprised me. Replaced it with a mopar gasket, paid close attention to fit up and it runs like a top. I lightly chamfered the two locating holes which may have helped it slip over the dowels. Thank you!

 

Thanks for posting back.

Even one of us blind squirrels finds a nut once in a while.

 

Great to hear it's all sorted. Until the next fault