280i idle speed too high

[440Interceptor]

Morning all, I've done maybe 50 kms since getting the 280i back on the road and all is going well.

One thing I need to address is that the car idles at around 1400-1600rpm when warm. I haven't touched the idle speed screw yet as I'm just letting the car get settled again after so long off the road, but this seems to be consistent each time I drive it.

Any obvious things to check?

[mrzigazaga]

Hi mate

If you blip the throttle via the throttle body does the idle return quickly and smoothly or does it dip and then return or even slowly return?

[440Interceptor]

Zig, I haven't tried from the throttle body and can't until tonight, but using the pedal it goes straight back to 1500rpm, no dip then climbing revs.

[mrzigazaga]

Mmm...If timing and all components like WUR...Metering unit and AAD are fine then you could try adjusting the mixture on the metering head...It sounds like too much air...You will need a long 3mm allen key and try not to push down on it when you adjust it...Make a note of where the allen key faces before you adjust it and makes sure its very small amounts..like 1/8th" at a time....Cant remember which way too richen it up though....

[440Interceptor]

I was thinking idle speed screw on throttle body inlet rather than mixture. Only issue is that at startup from cold it idles fine at 900rpm, so if I reduce idle speed it may struggle from cold. Anyway, I'll have a gander tonight.

[mrzigazaga]

Is the Auxiliary air device moving freely as it should be a slightly higher rpm on cold start up and then settle down.
Another thing to check is the outlet of gases at the tailpipe...If either one is "Chuffing" then that could indicate that the tappets need adjusting.

You could try the idle screw but do not touch the throttle stop or you could damage the butterfly.....

[440Interceptor]

turned down the revs at the throttle body, and all now seems fine. Been out 3-4 times and idle is now 1000 and steady.

[mrzigazaga]

440Interceptor said:

turned down the revs at the throttle body, and all now seems fine. Been out 3-4 times and idle is now 1000 and steady.

Sounds like your making progress mate...

[440Interceptor]

You don't know the half of it Zig! I have found that I have a very special car. The more I drive - I have done 100kms this weekend - the HIGHER my fuel gauge reads! Yes, I have a TVR the creates petrol!

Well, either that or I have made a bit of a blue with the sender unit...

Seriously though, I noticed this the other day and assumed without much thought that I had the sender unit contacts the wrong way around. Duly swapped them over and.. no difference. The needle is still resolutely heading for the full mark as I drive!

I can't see how I could have gotten the sender unit itself upside down when i put it back into the newly painted tank but in the absence of any other explanation ...maybe I have. I really don't fancy pulling it all apart at the moment so I'm going to see if it can be trusted the way it is, and tackle it some other time. 2 steps fwd and 1 step back!