toukao35

When I turn on my car on a cold start my rpm is bouncing from 1000 to 1500. After the car is warmed up, it goes back to normal under 1000. What could be the reasons for this?

holmesnmanny

The ris completely normal. The car is designed to idle higher at startup to help speed up the warming up the car(catalytic converter).

motoxxxman

no holmes, that is not normal. it should NEVER bounce. it should hold a steady idle at a steady rpm, which will gradually get lower and lower as the engine warms up.

make sure the coolant is topped off.
check for trouble codes; if there are any codes, fix whatever is causing the codes.
do a valve lash adjustment.
check for vacuum leaks. then adjust the idle (idle screw on TB, engine must be fully warmed up and iacv unplugged)

Sparksman

Nobody here mentioned the TPS or FITV as a culprit, I would check those as well.

mrboogler

The fitv is usually what causes this problem in my expiereimce

TonyZuc

Im having the same issue on my 98 Integra.. I've been told that after 96 they no longer had an FITV... is that true? I cant seem to find any information...

gstrudler

Yes they do. If it's the stock TB and there are coolant lines running to it, it has a FITV.

crazes

here you go in the FAQ section. https://honda-tech.com/forums/honda-prelude-4/end-all-idle-surge-bounce-etc-problems-thread-1979500/

ECKOHOMIE33

CHECK THAT YOUR TPS IS .5 CLOSED WITH KEY ON AND 4.5 AT WOT