S2 cutting out ... why?
- Thread starter zcacogp
- Start date
sawood12
New member
The afm mix screw is for adjusting mix at idle only on both open and closed loop cars. The engine doesn't run in closed loop (I.e. Off the o2sensor) at idle or wot. To adjust correctly you have to bypass the isv by making a jumper to short circuit some connections mounted behind the passenger strut top. The afm barn door is balanced by the airflow coming in and some airflow that bypasses the barn door and blows behind it. By adjusting the screw you are adjusting this bypass airflow and changing the barn door position at idle and hence the afm voltage output. If you adjust without disabling the isv, then as you change the mix screw your idle speed will also adjust and you won't set the right mix at idle speed.
I am with you all the way, and retain my skepticism. However, while digital, a relay with a bad contact can provide intermittent function, which can look analogue when softened by the vagueries of a fuel system (or so my hope goes!)
We'll see what the coming days and weeks reveal.
Oli.
TTM
Well-known member
How long has it been doing that?
Do the cooling fans run on low speed or on high speed only?
Now back to the erratic idle problem - for what it's worth I did 300 miles with my S2 yesterday. I shut it down when I got home, restarted it after I opened the garage door, and it idled fine with no stumbles as manoeuvred it into the garage.
I will still be cleaning the contacts as I feel the problem may occur again in the future.
ok, first off - please excuse my typing - i dislocated my shoulder at the weekend and hence am typing this one-(left) handed. and it hurts like buggery!
the cutting-out problem is looking good. i drove the car about 50 miles on friday in a variety of conditions andf it was fine. my wifethen drove it another 80 or so yesterday (guess why i wasn't driving - oh, you already have [
]) and that too was fine. comparethis with the fact that it cut out twice in the 15 miles before changing the dme relay and it feels promising. the idle is not rock-steady all the time; it will occasionally move around by 50 or so revs, but this could be due to a combination of factors and could well be unrelated. the very rough idling seems to be past - again, possibly caused by an intermittant bad connection in the dme.
the temperature / fans thing is a good q. if left to idle, the temperature gauge will creep up over 4 or 5 mins to about 1/2 way up and the fans will then turn on and bring it back down to the bottom third line, whereupon they will stopand the cycle will repeat. this, on reflection, is probably quite normal. it runs at a very steady tyemperature when moving, and iam probably jumping at shadows thinking there is a problem here. but - another q; what is the fan behaviour? i thought that the lowest fan setting was only one fan ruinning, and that they were individually adressable, although on my car they both come on at once.
thanks again for your help. i think my problerm may be solved. (famous last words, eh?)
oli.
the cutting-out problem is looking good. i drove the car about 50 miles on friday in a variety of conditions andf it was fine. my wifethen drove it another 80 or so yesterday (guess why i wasn't driving - oh, you already have [
]) and that too was fine. comparethis with the fact that it cut out twice in the 15 miles before changing the dme relay and it feels promising. the idle is not rock-steady all the time; it will occasionally move around by 50 or so revs, but this could be due to a combination of factors and could well be unrelated. the very rough idling seems to be past - again, possibly caused by an intermittant bad connection in the dme. the temperature / fans thing is a good q. if left to idle, the temperature gauge will creep up over 4 or 5 mins to about 1/2 way up and the fans will then turn on and bring it back down to the bottom third line, whereupon they will stopand the cycle will repeat. this, on reflection, is probably quite normal. it runs at a very steady tyemperature when moving, and iam probably jumping at shadows thinking there is a problem here. but - another q; what is the fan behaviour? i thought that the lowest fan setting was only one fan ruinning, and that they were individually adressable, although on my car they both come on at once.
thanks again for your help. i think my problerm may be solved. (famous last words, eh?)
oli.
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