91 N/A Engine Idle Gallop

[MR2 Illusion]

I've had my 91 N/A MR2 for 3 years now, and I've always had the same problem. It idles at 1500 rpms when it's warm. When it's cold, my idle gallops in rhythm from 1000 rpms to 2000 rpms. As it warms up, the rhythm gets faster. I've checked and cleaned my intake tube and filter, my throttle body, adjusted the idle screw, replace the vacuum lines, and I'm running out of ideas. Could it be my EGR? Can I remove the EGR and put on a block off plate? Thanks!

[OEMonkey]

It's not the EGR. A stuck closed EGR won't affect idle, a stuck open EGR valve will lower idle rpm or stall or cause a no-start. Fluctuating idle rpm is caused most of the time by the ff: defective ISC valve, air in the cooling system, defective ECT, exhaust leak before the o2sensor( will affect idle only after closed loop ), and I'm sure there's more (others will chime in.)

[tHa kNiGHt FaLL]

Originally Posted by OEMonkey

It's not the EGR. A stuck closed EGR won't affect idle, a stuck open EGR valve will lower idle rpm or stall or cause a no-start. Fluctuating idle rpm is caused most of the time by the ff: defective ISC valve, air in the cooling system, defective ECT, exhaust leak before the o2sensor( will affect idle only after closed loop ), and I'm sure there's more (others will chime in.)

yea... vacuum leaks... throttle cable.

i've had this same issue... i took apart my ISC and cleaned it. there was all kinds of dirt in there making the valve stick.

then it happened again... and this time the throttle cable actually frayed inside the tubing and would stretch out. and i would have never known, well untill the cable broke.

[RideMr2]

Originally Posted by MR2 Illusion

It idles at 1500 rpms when it's warm. When it's cold, my idle gallops in rhythm from 1000 rpms to 2000 rpms. As it warms up, the rhythm gets faster.

I had this problem, then I replaced and adjusted my TPS(right behind throttle body, 2 screws).

[MR2 Illusion]

Thank you everyone for your help. I'll try your suggestions and see if anything works!