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91 Prelude Questions - Engine Surging
Posted: Sun Aug 07, 2011 8:14 am
by gary.c
I just bought my 91 Prelude fr an older guy I knew. Model sr loaded great shape sun-roof,auto.trans.paid $2,000. did I pay to much? Also it wouldn,t start when I tried it. Couldn,t smell any gas after a few times trying it got under and hit on fuel pump in gas tank ,car started . no problems rest of day or night.Went to started today car started but surgeing when idling cold. Is the fuel pump bad???..old guy said no..can,t be pump because it wouldn,t start at all.
Re: 91 Prelude Questions - Engine Surging
Posted: Mon Aug 08, 2011 12:50 pm
by spiffyguido
A surging cold idle is almost always caused by a faulty IAC valve. This is the valve that is located on the fire-wall side of the intake plenum right next to the throttle body. It has to two water lines attached to it.
If you remove the cap (two screws, do it when the engine is cold) you will see the plunger that is supposed to move up and down to make the valve work. Sometimes these plungers become detached from the shaft they move on. Using a large flathead screwdriver they can be threaded back onto the shaft.
If the plunger has not unscrewed itself, the valve will probably require replacement. I've always had good luck getting used ones from wreckers to save cost.