when my car is first started on a cold start to warm up the engine will rev up hold for a second then drop and will repeat that for a while (till its warmed up).

i have no idea what the RPMs are cuz my tach doesnt work. this is on a B18A1 motor...

please help this is ------ annoying..

 

vacuum leak?

 

Vacume leak or a hose is clogged...

 

check coolant level and check for air bubbles in coolant. as well

 

unplug the throtle positioning sensor. Thats what i did when mine did that and now it idles at 2000rpms when it first starts but as soon as i boost and the check engine light comes on because of air pressure it idles right where it should. There is probably a better way of doing it but that worked on mine.

 

sounds like your coolant, if it was a vaccum leak, it wouldn't stop when it's warmed up

 

there are no codes btw...


coolant? you mean there is air in the system? i have bleed it on many occasions and still does it. guess i will keep trying that...

i also swapped out the IACV with another one, didnt change a thing...

 

Bet its your cold enrichment on your zdyne.. lemme take a quick peak at your tune next time your around.

Jeff

 

k, an update... still ------ does it all the time, up and down up and down. REALLY ------ ANNOYING! thought it had to do with the EGR valve (think the gasket was torn) had a plate made and new gasket, still didnt help. swapped out the IACV, nothing. keep bleeding the coolant, nothing. if its a vaccum leak i dont know where its coming from. also there are NO codes being throw...

 

ok the book says either when cold/fast idle out of spec, coolant temp sensor. Or rough idel, map sensor. Now with my experience when doing engine swaps its never what the book says so take this with a grain of salt.