kidso

Hi,

I have a 1998 XJ 4X4 with 94,000 miles. I've had zero problrms with it over the last three years since I bought it with 64,000 miles. I was recently having increased rpms at idle, so I replaced the TPS. Since I was working off the throttle base, I went ahead and pulled the IAC valve and cleaned it with throttle cleaner. I did not push the pivet end inward while cleaning it, I simply sprayed and rubbed it clean with IAC/Throttle cleaner. I also carefully sprayed and wiped out the throttle butterfly and base. None of it was really that bad, just a small based layer of carbon on the IAC valve, but no real thick carbon anywhere.

Anyways, upon reassembly and start-up, I do have reduced rpms, almost to the point that it seems like the engine wants to stall. You can clearly hear at idle the engine slowly cycling, kind of like a starter cranking over. It is not smoothe and even as I was expecting.

Here are my questions:

1) Is it even possible to put the IAC valve in the wrong way? It is mounted with 2 screws in vertical positions, so it is possible that I could have remounted the IAC valve with the old top part now orientated on the bottom and vice versa. Could that cause this scenario?

2) Could I have damaged the IAC valve while cleaning it? I cleaned the carbon off the pivot tip and its adjoining rod, but could still see carbon higher up on the rod where it goes into the main body of the IAC valve, where I could not clean it. Could this affect its performance?

3) Should I just replace the IAC valve?

Thanks for your ideas.

Keith
.

Radi

I'd replace it. Sounds like it's sticking now.

DFlintstone

Just a 'side story" My idle was doing that (on my 90). It didn't really bother me. It would get really low, then surge up a bit, even off, then drop and repeat. 20 sec? 30 sec?

Anyway I put that off. I got after my 02 sensor for other reasons and found it was stone dead. Another footnote there. Flying down the freeway, mileage wasn't too bad...but knocking around really sucked. (also it was slow coming up to heat)Soo

A little surprise. After I replaced the 02 sensor, the idle smoothed out, nice and even now. (Heat comes up almost twice as fast), and gained at least 2 mpg, 'knocking around".

Mr Talon

I might try the o2 sensor. My 90 idle surges after a long drive and I put it in Park or Neutral.
Good info.

DFlintstone

Here is my "experience" with it. A bit choppy, than Rrich came in all confused about what I had. First thing is a NAXJA link with more 02 sensor info. (there I learned allot, including the 02 heater business) >>>
https://www.cherokeeforum.com/f2/ren...ce-rms-133153/

Bustedback

You might have screwed the MAP sensor up with the throttle body cleaner.

kidso

I had the MAP sensor and its wires covered with a towel during the process and only spot sprayed the throttle cleaner into the throttle and on its butterfly valve and wiped it off with an additional towel. The spray never touched it.

DFlintstone

Slowly cycleing is what mine was doing.

rrich

As a 98 it's actually a simple fix - but we'll let the "expert" on old Ramblers tell you.