My pre-facelift 1984 320i L-Jet E30 is having some high-idle issues ever since I've got my hands on her.A while ago I visited a local independent BMW 'specialist', who informed me that the only way to solve the issue was to get the replacement illusive 'Idle Control Valve/Water Slide Valve', having finally got hold of one I am now ready to replace the existing one in my beemer. You can see the said items in the pics below....although you may have difficulty distinguishing which one is the replacement one!
The thing is...after giving it some more thought and not really knowing whether the replacement is going to be anymore functional or reliable as the one thats in already in there I have become somewhat hesitant and also questioning whether this will actually solve the issue at all. What got me thinking was as I was looking at the valves I realised both where in the same position, which I'm assuming is 'open' as they are both 'cold'. Now should the one thats already in the car be malfunctioning it would be reasonable to think that it wont actually 'close' when the engine warms up and that the engine would have a problem when warm , this however is not the case...the idle seems fine when the engines up to temperature - about 1200 RPM.
To summarise the issue:
- On cold start the engine revs rise slowly over about 20 seconds to about 3000 RPM
- The engine has the occasional 'cough' here and there where it seems to either misfire and rev's drop very momentarily, very slight rev fluctuations and the occasional jolt
- The engine seems to be running quite rich
- Starting is somewhat unpredictable, sometimes starts straight away and sometimes needs to turn over a few times before starting.This does not seem to matter whether starting from cold or when warm.It does however ALWAYS start...
I'm starting to think that the issue is one of either a vacuum leak maybe alongside a TPS issue, also maybe the injectors being leaky.
TPS has definitely seen drier days!:
I'm going to test it and see how it reads out however.
I'm just wondering if anyone had any thoughts or experience on these issues and this bloody valve?