Lo Revs & Cutting Out

[clairekreetzer]

Hi!

Just wondered if someone could help me. I have a 95 Celica GT Import. The car seems to be having trouble idling. The rev counter needle fluctuates slightly, i can see the revs dropping, at points the engine judders and feels like it is going to cut out. it seems to be idling much too low and cannot level itself out. this doesn't happen all the time but just recently the problem is getting much worse and it is doing it more often than not. Also occassionally the engine cuts out when i am changing down gears - could this be part of the same problem - that the revs have just dropped to low and the engine has cut out??? Does anybody have any suggestions as to what is causing this? It has been to the garage and had all the pipes checked - there are no blockages or splits, i have also have my fuel filter changed.

Thanks,

Claire

[GT4 BOOSTER]

disconnect the Battery press the brake pedal 2 times wait for 30 seconds then reconnect Battery - this will reset the ecu back to factory defaults , the car will then learn your driving style and hopefully cure your tick over - if not you may need to look into things like new spark plugs,rotor arm ,dizzy cap , leads etc. or have the throttle position sensor set up by a professional.

you could always just turn up the tick over screw located on the throttle body

[mikeb]

I don't think there is a manual way of ajusting idle speed - the ECU does it all under closed loop. The only component to check (directly) regarding idle speed is the idle control valve. Make sure it's not gunked up. If it was faulty, I think your idle speed would be constant and probably on the high side (2k rpm). From your symptoms it does not sound like the ICV to me though, and these kind of faults are usually mechanical.

Also check for vacuum leaks (split/disconnected hoses) on the inlet piping, especially the piping to the MAP sensor.

I doubt that resetting the ECU would achieve much - the only relearning part is the idle contol valve characteristics (although if it is clogged up an ECU reset would be required following cleaning). Resetting the ECU just causes an erratic idle while the ECU relearns how to get the correct idle speed back.

It may be worth doing a compression check, if you have a compression test gauge.