96 850 Turbo- Still having Idle problems, suggestions?

[mlance2]

I have been dealing with this problem for quite some time now. Basically when I start the car the idle fluctuates between 700-1200 rpms, and throttles itself back and forth. While in Park or Neutral it will continue to ide back and forth, but once I have put it in gear (reverse or drive), the rpms will decrease (and die) if gas is not applied. Here is a list of repairs I have done so far:

Distributor cap
Roto Button
Spark Plugs
Ignition Coil
MAF sensor
Throttle Positioning Sensor
Three vacuum hoses labed yellow, red and blue which are attached to the air fliter container

My check engine light is now off and the idling problem has improved, but there is still the constant fluctuation of rpm and occasional dying. Any suggestions or solutions? I have read these might be possible solutions: Idle air control valve, Fuel Regulator Sensor, or possibily a cracked or broken intercooler line from under the car.

Any ideas or suggestions would be greatly appreciated

Thanks Guys

[matthew1]

No codes?

[jblackburn]

What codes were on before with the check engine light?

I would definitely clean the idle control valve and throttle body if there are no longer any codes.

[mlance2]

So check engine light did come on, which showed codes p1310 and p0300 and I'm fairly certain those are for misfiring for the cylinders. I cleared them this am and they have yet to show back up. I did not replace the spark plug ignition wires, I ordered them and should receive them tomorrow or thursday at the latest. I believe this might be a solution to the idle which now is less prevalent but still noticeable at times. Thoughts?

[JimBee]

Question: at highway speeds, does it straighten out and run normally?
If so, I would think this might eliminate plug wires, since if they were shorting, they'd most likely do so at any rpm, under load or not. What do you think?

[mlance2]

The idling is drastically improved from where it was, but it is still there, while yes the car runs fine at highway speeds, you still feel the misfire in while driving every so often, which is to say you feel it miss and then catch it self even if it is ever so slight, i think the wires may still work since it is the only thing I didn't replace in the sequence from plugs to coil. The only other thing is to clean the idle air control valve which may be the cause as well

[JimBee]

I asked about the highway performance b/c I picked up a '96 turbo last August that has a similar condition—only wildly erratic when idling cold. I drove it on a 70 mile highway trip and warmed up, it seemed pretty normal. It's been sitting since, but I'll be back playing with it soon. I'm wondering if it's a vacuum leak. I plan to replace the elbows on the vac lines and the throttle body gasket. I've done most of things you listed and the problem persists. Keeping it running while it was surging and dying must have flooded the cylinders b/c my cat go really hot. So I also plan to clean the injectors, replace their seals and maybe have them checked if I can find a shop that does that.
Someone posted a couple of months ago about pouring paint thinner in the gas tank and letting it run through the engine to clean things up. There's a UTube video posted by a mechanic who says he's been doing it for years. I'm going to post a question to the group about it.

[steve850]

The paint thinner is for the CAt. New wires and clean up the throttle body.

[Sean-E-Boy]

1. Check the vacuum line connection on the left of the intake manifold.
2. Check/test the EVAP system.

On my 850, disconnected vacuum line at left side of the intake manifold caused rough idle and rough low end acceleration as well as the misfire codes.

Also, broken lines on both sides of the fuel tank roll-over valve resulted in spontaneous stalling (sometimes 2 or 3 times a day, other times a week or more between stalls). What's worse, A-2 never logged a trouble code for the EVAP, only discovered it after failing that portion of the smog test.