engine rev itself up and down while car stand still

[subie]

Hi guys,

i have civic ed6 with twin carb engine. this problem just happen a few days ago and it continue to accur

while the car stand still sit on the red light, i have noticed that the engine rev itself up and down. the engine rev from 900rpm to around 1500 rpm for few sec and droped back to 900rpm. then, took around 5mins to do it again

what would be the problems?

thanks in advance

[rayb3na_]

does this only happen when your car is cold or always?

[subie]

does this only happen when your car is cold or always?

in normal temp. and always

cheers

[tiksie]

Try cleaning your IACV, FITV and bleed your coolant.

Most probably a vaccum leak

[Mr EG]

Vacum leak?

[subie]

just realised it only happenned on a very hot day (like yesterday). seem to be ok today.

could it be the fuel is very hot and make the mixer wrong ?

[tiksie]

Have you checked for air pockets in your coolant ? This COULD be the issue since it was on a hot day.

[2MPRS]

Does it happen when u hold the brake only or when u car is just idle in park?

[Rosco]

was your air con on? Mine does that a little when i'm waiting at lights etc. but not when the air con isnt on....

[subie]

Have you checked for air pockets in your coolant ? This COULD be the issue since it was on a hot day.
How?

Does it happen when u hold the brake only or when u car is just idle in park?
not sure about hold the brake but it happenned when i parked in the carpark and sit in the traffic

was your air con on? Mine does that a little when i'm waiting at lights etc. but not when the air con isnt on....
Both aircon on and off

thanks for all your inputs guys

Cheers

[2MPRS]

How?

not sure about hold the brake but it happenned when i parked in the carpark and sit in the traffic

Cheers

Just asking cause mine did the same thing when it was in idle. I changed the brake booster and it stoped the crazy revs, dont know if it's the same for u though

[subie]

Just asking cause mine did the same thing when it was in idle. I changed the brake booster and it stoped the crazy revs, dont know if it's the same for u though

Thanks for your input mate

:thumbsup:

[Fly-Rice]

I had ther same problem, cleaned my throttle and it was fix.

[subie]

I had ther same problem, cleaned my throttle and it was fix.
but mine is twin carb

[Latino CRX]

had same prob while ago all i done was controlled the air intake screw soo it wasnt suckin heaps of air .. been told wen the revs play up like that .. that ur car is suckin more air then it should be so try lowering down the air intake see how that goes .

[5thgen_prel]

had same prob while ago all i done was controlled the air intake screw soo it wasnt suckin heaps of air .. been told wen the revs play up like that .. that ur car is suckin more air then it should be so try lowering down the air intake see how that goes

^^^^how do u do tat??

[Latino CRX]

there should be a screw lookin thing around the throttle body which controls the air intake use a flat head screw driver and wind down

[EDracer]

i know in fuel injection cars this is caused by the stepper motor. this is a little solinoid that changes the engine revs when there is abnormal drain on engine (ie air con) cause the iar takes power from the motor the stepper motor ups the revs to compensate. because it is a carby motor, i would check the vacume lines. there is one from the brake booster to the intake plenum and there should be a "one way" valve there too, check all these are working ok and are not blocked.
i would also do an ECU reset. disconnect the battery, unplug the ECU (located under the passenger side foot kick pannel, under the carpet there is a zinc coated pannel, ECU under this.) leave the ECu out for 3-5 mins, plug back in, plug in battery and start car. let it idl for about 15 mins and turn the car off. after that take it for a drive and get up to temp. see if it is doing it still.

[nikiol22]

Civic EK1 2000 CXI

i got the same problem with the car reving itself when its in neutral. Heres the story:

I left my car undriven for around 2-3weeks, uninstalled my rsm, tacho, amp + subwoofer and neon lights. As it hasnt been driven for so long so the battery is flat. I recharged it and took it for a short drive around the streets and when it in neutral i realised the engine reving itselfs. Why does this happen?
What do i need to do to fix this? Or theres nothing i can do other than taking it to machenic and cost me heapps to fix?
PLEASE HELP!

[beeza]

^^ Answered in your thread.

No need to ask twice :)

[nikiol22]

i reset the ecu and the problem still happens.
cant find the screw at the throttle body

[beeza]

Check ya other thread Yo!

[aznalex]

unsure if this will help
but i had a 95 eunos 30x automatic before with your problem
revving strangely at idle

turned out to be an alternator + spark plugs combination which was stuffing up revs