IAC Question...misfires and more

1996 JGC 4.0 I6

Many of you have read my problem before I'm sure, but I am looking for an "AH-HA" moment here to finally fix this thing.

History:

Manifold crack welded (Nov 05), New CPS (Dec 05), New TPS (Wells brand though), plugs, wires, cap (MOPAR tune up kit), catalytic converter, IAC (See below), new higher performance coil, fuel filter, all done within the past couple of months. Cleaned with MOPAR combustion chamber cleaner (once), battery and alternator test good as of 5/20/06.

Been struggling with this thing for a few months and my Jeep guy swears it is not te CPS because the computer is not picking up any variation at all in signal loss, but here's the symptom I've definately got right now:

I had a new IAC that I did not adjust properly when I orginally installed it. I think I had it around 1 5/16" or so because I misread the instructions and went off of the old one (which could have been altered at some point by accident by the time I checked it).

How long would it take to damage the IAC with it installed at the wrong length? I have readjusted it to the recommended 1 1/8", but I still have a Hi-Low, revving and stalling shift on the TAC from 450-900 or so when in DRIVE (every 15 seconds or so) and brake applied. Also see it in PARK or NEUTRAL, but less variance, same timeframe. Never completely cuts out in either case.

I don't want to get another IAC unless someone thinks I really trashed this one the first time around (Yes, I disconnected the battery first too, just for reference, but also see my other problem below and "could" it be related?) And could it be realted to the below...

Note:

I have a mult cylinder misfire issue that has not been resolved for months. Could this new IAC be accurate enough to show misfires in the TAC or would they be so small I probably wouldn't notice unless I had a ScanTool?

How about bad valve springs or a bad CPS and the IAC is just new and good enough to pick up either of those not performing up to par?

Again the only code ever thrown is for mult cylinders (43) that misfire from time to time. Sometimes runs great, sometimes sluggish. Used to be at high and low speeds but now mostly on acceleration from dead stops at a light or on ramp, for instance......

Hope someone can help....the frustration is mounting....

Bryan

Do you have AC? Pop the hood and see if your ac clutch is engaging just as the idle speed changes, Unplug the compressor for a moment and see if your idle fluctuation continues.

If the AC system has leaked down the compressor will cycle like that. Happened to me when I first had the vehicle. A recharge will stop it or leave the compressor unplugged.

Well....you were dead on with that one.

No question that is causing my major idle problems. I also noticed frosting on the hose going to the accumulator after letting it run for a bit with the hood open. Apparently that is also a sign of it being low. I'm going to recharge it tomorrow (if the weather is good) and go from there.

Now, if I could only solve my problems with the misfires:banghead:, I'll be back in business and running like a top.

Thank you very much for the A/C info, I would not have found that one.

Bryan

Glad to be able to help! :cheers:

A few quick questions.

Looking at my Haynes manual (I have not done this before) do you think that by now I would have R134 or still R12? I think it was probably refilled a few years ago when my evaporator went bad, but I'm not sure what they used.

Also, should I take this somewhere and have someone do it for me just to make it a quick job or should I just get a kit from somewhere and do it myself? Would it be outrageous to get someone to service it for me if I have never done it before? What is a reasonable charge for service?

Thanks,

Bryan