Yes, I've been chasing a problem on my 2000, Jeep TJ with the gutless 2.5l. It was runingrough and I discovered an issue with the head on #4. So I replaced the head entirely with a rebuilt head. Along the way, I replaced much of what I touched too. Fuel injectors, alternator, power steering pump, water pump, thermostat, and of course the throttle body. Yes, all the gaskets too. When I put it all back together it started right up as soon as the fuel hit the injectors. But it ran up to 4500RPM. Ouch. so I did all the obligitory research. I dutifully changed the IAC to another new one, the TPS, vacuum lines and those deteriorated rubber elbow that are used. Those are a real pile of crap and not so easy to get replacements... but I digress. I have seen that some members insist tha tthe manifold gasket is the culprit. I've replaced that 2x. OK, the first time I installed it backwards, how I or why I did that I have no freakin clue, but I did. I replaced it and tried again. Still 4500RPM. Each and every timeI made changes or tested a new solution, I would read for codes, nothing, and then disconnect the battery, generally overnight. still I am vexed as to what could be the issue. for those who insist on the IAC, well I tried something today as a last resort, I put tap over the slit on the hole where air goes into tehTBI around the butterfly. I figured if it were the IAC this would certainly have an impact on it. Nope, nothing except an erorr code telling me what I already knew, there was an issue with the IAC, no duh, I put tape on the hole. I am at wits end, any thoughts? The ECM is the only original part under the hood.
Trouble with high idle
- Thread starter GWL62
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- tj 2.5l high idle
Imapepper
TJ Enthusiast
Imapepper
TJ Enthusiast
Hmm, in retrospect this would have been way easier than what I did.... So, I just replugged all those barbed fittings with tight rubber caps and covered the top of the TBI completely. Damned thing started right up to 4500RPM again. BUT this time there was a whistle! I need some further investigation here but I think air is getting sucked in from around the injectors.... is this possible? I NEVER considered that as a possiblity and these are brand spanking new.... But I now got a trouble code. Apparently the engine knows that some fool covered up the TBI.
The first thing I would have suggested would have been vacuum lines or the manifold gasket. You've officially got me stumped. Maybe something isn't plugged in, or a sensor is bad?
It is highly (!) likely it's nothing more than your intake manifold was not properly seated before tightening its hardware. Sorry to say that the only way to get it seated properly is to unbolt the exhaust manifold and carefully reinstall the intake manifold. This is a very common problem after doing anything that requires that the intake manifold be removed and reinstalled. Getting it seated properly is not something that can be rushed in the least.
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Well after some more investigation, for some reason I decided to remove the manifold again with the TBI attached. and there it was. I put a rebuilt TBI on the jeep and every time I removed it and put it back on...several times I might add, I never once noticed that there was a casting Boss on the IAC housing that was interferringwith my manifold. I saw the space under the TBI only because this time I ran out of TBI Gaskets. So, now she purrs like a kitten. And yes, it has the poower of a kitten as well, but it works well for me at the moment. I have other plans for this Jepp moving forward. Right now, I am all too happy to get it back on the road again, top down, and have some fun! Thanks to all for trying to help me, I will confess I was pulling out my hair...I wish I ran out of TBI gaskets sooner!
Imapepper
TJ Enthusiast
Glad you figured it out. By the way, our TJ's just have a plain TB, the days of TBI are long gone. 