idle surge when cold
 

i need help!!. My 1988 13b has a problem, maybe 2 or 3 problems. when starting up from cold, it initially starts well, then after about 10 seconds the revs drop from about 2000 to under 1000, then surges up and down to 2000 and back but never stalls. Also when it is warmed up, the surging idle goes away, but trying to drive it smoothly in traffic is a nightmare..it jerks and surges on very light throttle positions. even when slowing down and no throttle, it jerks about. i susspect a vaccume leak, but from where?

If you still have the thermowax unit attached and assuming all else is stock, it should rev to 3k rpm for 17 seconds then drop to ~1,500 rpm unti the thermowax is melted by the heating coolant. Once the engine is at operating temp., the idle should drop to ~750rpm. The surging indicates that the TPS may need to be adjusted.

B

adjust your TPS. or mabe its your bac valve

ile try adjusting the TPS..i take it that means throttle position sensor?..if i find it, whats the setting?