Anyone else experience this?

[Dds1990]

Being a nice day yesterday I decided take 90 #0106 out for a drive. I live in a rural setting and it ran great. After about 30 minutes I ended up in town and stopped by fast food drive thru. While sitting line the idle started moving from 800 rpm to about 1200 rpm then back to 800 rpm about 4 or 5 times After leaving the drive thru stopped at Shell to top off the tank and drove home without the issue happening again. I did put some stabil in the tank in November, don't know if that could have anything to do with it. It ran great and no SES light.

[BigJohn]

If your car uses premium fuel and you're storing it for only a few months; you really don't need to add stable.
Premium fuel does not break down as quickly as regular.

[DRM500RUBYZR-1]

I seem to recall that early production 90's were known to have the "hunting idle".
I also recall that there was an update to the prom that resolved or minimized this.
Lastly, I knew many owners of 90's cars that encountered this, and elected to leave it be, except for 1 or 2 where the idle hunted up much higher than 1200, more like 1900.
Sometimes the "cure" is not worth it, if the problem is minor and infrequent.
My 93 has an occasional bout of high or hunting idle, but so transient and rare that I just never bothered to pursue it.
If it begins to happen more often than not, then it should be diagnosed.
Otherwise, let the ghost have his way with your accelerator.

Marty

[Dds1990]

Thanks, I agree with the ghost thing I have had the car since July and it was the first time,.I can live with that.

[Dynomite]

I think if you were in line and even slightly moving the idle will hang at 1200. If you completely stop for a few seconds then the idle will drop to 800 but if you creep forward may be back to 1200.

[Dds1990]

That makes sense didn't think of that..Thanks Dyno

[lfalzarano]

You should upgrade you chip to GM release AYBKG for your 1990.
Http://www.zr1specialist.com/HAT%20W...on%20AYBKG.htm

Marc Haibec sells the chip and it addresses problems with idle fluctuation. It solved my 1990 issue also.on


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[Dds1990]

Thanks for the chip info. I have been wanting to do that, now I have a reason....

[billschroeder5842]

Originally Posted by Dds1990

Thanks for the chip info. I have been wanting to do that, now I have a reason....

I did a Haibeck chip in my 91 and it smoothed out much. It is the best 30 minute install you ever spent.

[Racinfan83]

X2 on the Haibeck chip. Got rid of that pesky 1-4 shift deal too. That was worth the price on it's own...