Chasing idle issues on a 97 TJ 2.5

[Oyoung97tj]

Hello I have a issue that I have been chasing for about a year now with no luck. I own a 97 tj sport 2.5, for the last 8 months or so I have had idling issues where the rpm’s go from 1000-3000 Erratically when I am sitting still. Also when I start to go, there is short bursts of power loss, once I reach 3rd gear and the sputtering and power loss stop. It seems that after driving about 5-10 miles the issue improves but is still good there. I have had a fuel service done, changed out the TPS, and IAC valve, had a pressure test done which passed with no problem and have had the PCM replaced with a refurbished unit. The PCM was the last thing I have had done under the instructions of my mechanic. The final diagnosis from the mechanic was that there was water in my PCM, changed it and it is still doing the same thing. Any help would be great, I really don’t want to sell it but if I can’t get this figured out soon I will have to.

Thanks

 

[JEEPCJTJ]

Any help would be great, I really don’t want to sell it but if I can’t get this figured out soon I will have to.

Thanks

Welcome to this forum where there are at least a few Jeepers that can help. I'm not sure why your 2.5 is doing that stuff.

I'm also not sure why 18 hours later post #2 is finally happening but It may have something to do with your thread title asking if this is the troubleshooting thread. While I believe it could very well become the thread for troubleshooting your 2.5's behavior, a better title might be something like "I love my 2.5 but it ain't running right!"

I will give warning that at least one post will say you need an LS and another may say a Hemi. If I was choosing one of those and had the money and ability to do things like that I'd take the Hemi in a heartbeat.

Good Luck

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[TJ Jim]

Pretty puzzling problem. I read it a couple of days ago but guess it scared me off of taking a guess. I suspect you’ve got more than one problem involved in this. The strange idle would be the first problem I’d look at and I’d go for a vacuum leak that maybe changes as your motor shifts positions when accelerating.
Second if that didn’t produce a solution is look for an electrical problem, like how the wires along the firewall can sometimes rub through and short out.
Just guessing.

 

[Wildman]

Since you have a 97 TJ it's also helpful to know when it was built.
The first few months of production have small differences with them than later. Ones made from 01/96-03/96 fall into that category.

I'm with TJ Jim that the idle issue sounds like a vacuum leak. It could be on the intake manifold or a hole in a line.

I have one of the early build TJ's also and it used to be a 2.5 4 popper but I glued 4 more cylinders to it. I've got a Dodge magnum V-8 in mine. Which IMO is the easiest and most economical V-8 swap for our TJ's.

 

[P man]

How is the vacuum line that runs from the intake manifold all the way to the heater and then down to the vacuum resevoir in the fender?