A.t.p

My Rs turbo S2 idles at 950 rpm as it should and pulls alright (maybe a slight hesitation when accelerating at low rpm, but not completley sure) but it is pretty rough at idle, and when i drive op to a red light signal or some other kind of stop, my idle drops Down at 500-600 rpm and then comes back up to 950 rpm again after 5 seconds or so, and as i mentioned, it then idles rough.

Could it be my auxiliary air valve? Or have you got any other suggestions? :/

Cheers

Chas

That is strange. What happens if you put the brakes on with the car at a standstill? I know when I had an earth fault with the indicators the revs would drop by 100rpm at the traffic lights everytime they came on. With all consumers on the revs drop a bit again. I wonder if you have a vacuum leak from the servo.

How much fuel do you have in the tank? When running low (which is now never in my car!) my car would sometimes cut out or try to cut out dependant on the amount of fuel in the tank.

The AAV shouldn't really affect it. It is quite simply a disc which is open (thus allowing extra air into the engine at low RPM via bypassing the throttle) which will eventually close up once the element heats up off its 12V supply.

A.t.p

I have had the problem for a long time, and the amount of fuel has no influence on the problem.
Neither has the brake :/ as i Said, it drops as i stop the car almost as it's about to die/stall, and the goes back to 950 rpm and stays there, and that is with or without toutching the brake :/ i should also mention that when i start the car, the car sometimes crank a few times before it starts and then cuts off imidiatly and then i Can start it just after with no problems. Other times it starts without cutting out but then runs lumpy at idle the first 10 seconds.

I have changed, coil, plugs, distributor cap, rotator arm and leads, and i have had the timing set correctly.

I can't figure out the problem, and it just ruins the experience

slammedorion

Has it got a speed sensor in the box where the speedo cable sits?
Could be faulty if it has...

Chas

Running on KE jet I doubt he will.

Have you seen how clean the air sensor plate is? On a Volvo 740 it ran alot better after simply cleaning that. That used to almost stall at junctions for a while.

A.t.p

Yeah, i just cleaned it the other day :/

A.t.p

I have just been out driving it, and tried pumping the brake pedal while holding still, and as son as i start pumping the pedal, the rpm goes Down, but not if i just hit it once, is this normal, or have i found a possible leak?

rst69

Hi Guys


I had a similar experience with mine. One day I was at a red light and the idle was so rough it nearly stalled unless I gave it some revs. I parked up and found that the dipstick had popped out slightly. Once I secured it back in place the idle was spot on again. No problems since.


Just a thought it might be something as simple as that with yours.


Toby

Chas

K/KE-Jetronic is sensitive to vacuum leaks which can be caused by something as simple as the dipstick not seating correctly or the oil filler cap not being on tightly ; pattern caps can be more trouble than they are worth here. On an old XR3i I managed to raise the idle by simply changing the oil filler cap due to the 'new' cap being prematurely worn. Of course, this only applies if the car is running a stock breather system and not an oil separator type ; the crankcase system them no longer influences the running of the car, well, not as much as before.

IMHO without knowing more about the car I would say the issue is the following from what has been said:

1) Poor brake light earth causing the car to run bad (I have had that before on a Ka ; it took an age to diagnose that! The earth actually began to heat up!)
2) Vacuum leak at the brake servo or pipework. Clamping the brake servo line should rule this out.
3) Injection issue - either the mixture is not right or there is an issue with the sensors; be it the TPS (although I doubt it could affect it much, but I have seen this fault affect a car on K-Jet (the throttle switch was not turning on, tweaking the switch made all of the difference) or the electropressure regulator is faulty (this takes place over the overrun shut off valve that is present in K-Jetronic cars). Revving the car and letting it idle again should rule this out but of course it probably not that easy.

I am sure someone else with a better idea could give more conclusive pointers .

A.t.p

Appreciate your input, but just like you i have also experienced that, it sometimes happens if really drive it fast on the highway. So i am Aware of the problem, and the problem is not the dipstick with these problems i'm having at the moment :/

A.t.p

I checked the brake servo earlier today, nothing seemed to be wrong :/
I Will try to buy a new oil cap and see if that has an effect

And Will also check for the other faults you mention.

thank you for your answer

Would love to here more from
Others too.

Karl @ FPT

I haven't read the whole thread as I'm in a rush but have you checked for air leaks? Most common cause of rough idle and hesitation at low RPM.