Not a VW but my BMW and there is a large collective wisdom here. Without any load I have a small issue. When coming to a standstill the revs drop low and the car almost wants to stall. This is more of a cold issue. However, when I put the lights on and the blower on position one the car stalls when coming to a stop. This happened almost every time I stopped in a five mile journey. The car then rested for 30 minutes or so and the issue mostly went away. What should I be looking for? Some googling suggests it may be the alternator not being man enough or the regulator not working properly. I need to do some voltage checks at the battery (new) and get some idea of the values under different scenarios but any other suggestions will be gratefully received.
Which BMW? With the E46, this is a known issue caused by the crankcase ventilation, although the connection with the electrics is a bit odd. On the other, I always drive with lights on and the blower on automatic (so on).
It’s an e30 m42 engine in a 1602. The engine is essentially brand new having just come back from full rebuild. There shouldn’t be any air leaks but I agree air leaks are a know issue on this engine.
Oh brother, that's an oldie. Can you check for leakages with brakedisc cleaner or something? Would be the easiest thing to check. Is the engine with carburetors or injection? Is the idling rpm OK?
It’s fuel injected. It’s not a 1602 engine. It’s a 1991 engine. Coil on plug, fast road cams but with the original ECU which “could” be a factor.
Carb cleaner sprayed everywhere - no air leaks Battery. Resting voltage, last driven last night. 12.74 Running, no load 14.30 Running. Side lights on 14.26 Dipped beam on 14.17 Fan only 1 14.24 Fan only 2 14.21 Fan only 3 14.19 Dipped beam and fan 1 14.12 Dipped beam and fan 2 14.10 Dipped beam and fan 3 14.08 Engine off 13.65 Engine off volts gradually drop at battery to about 12.74 This all seems fairly normal. Also, the engine did not want to stall when switching the items on. Will need to take for a drive again to see if the issue remains.
It's a possibility, my '92 Mitsubishi has an idle learn function iirc. Have you got a base idle setting procedure to run through?.
I would give the engine bay a good check over Phil - wiring, connectors, sensors, ground points etc. With the engine work, something may have been disturbed/broken. BMW lumps from that era are pretty straightforward and devoid of modern complications. With that said giving her a damn good thrashing as well as the old ‘Italian tuneup’ might also work.
Not familiar with that type of engine does it have an idle speed control valve as said above may need the idle base setting done if possible.
On the old Fords I used to work on of that era you used to disconnect the ICV then set up the throttle stop or air bleed to a specified RPM, reconnect the ICV and done. edit I did a Google and it says that the throttle stop should not be fiddled with the idle is computer controlled via the ICV, So thats useful..not. Guess the ICV might be gummed up?
