US 280i idles way too low

[hayduke]

My 280i just got uncorked for the spring, got tuned-up and scrubbed down.

Unfortunately, it now has a low idle condition that gets worse when warm.

According to the shop, the injection system is working properly all around, with adequate fuel pressure and new fuel filter. I don't necessarily disbelieve them, thev'e got experience with this car and with the K-Jetronic. Of course we've tried the idle adjustment, but it is set at the maximum limit and this doesn't help.

Cold idle is at about 600 rpm, just enough to keep it turning. Coming to a stop after cruising at highway speeds will cause a stall. Restarts are fine.

Any suggestions ?

[jeff m]

Hayduke,
The air bypass (that bypasses the butterfly) is quite a large hole and if it isn't blocked will give you a lot of air.
Air is all you need!
The CIS will take care of the rest.
Check the bypass isn't blocked.
If that is ok, then maybe somebody closed up the butterfly. It's supposed to be a factory setting and not touched but I'm sure with cars this age sombody could have messed with it!
A can of carb cleaner is hopefully all you need.
Jeff

[mikek]

hey, i had a simular problem w/ my 280i last year. i took it to motor car international in bridgewater ma. its probably just under a 2hr ride from you. they worked on quite a few 280i s in the 80s. they are very good w/ this form of fuel injection. most of their work is on volvos porsches saabs and odd cars like that that have simular injection systems. they do really good work and very reasonablely priced. their number is 508-697-5921

[sjp76]

Hi,

This is a subject that I can only just bring myself to talk about. You will see loads of threads on here from me about this and you may be able to pick up something on there.

In my case, it turned out that the tappets had been wrongly adjusted and the engine was down on compression (I'd exhausted all injection system possibilites by the time I'd realised). The symptoms were exagerated when warm because everything expands when hot (gaps between valves and their seats effectively got bigger).

Have you had a compression test done?

regards,
Steve

>> Edited by sjp76 on Friday 2nd May 13:44

[hayduke]

Thanks Guys - I got the problem fixed now. I just had to readjust the idle screws and give everything a blast of carb cleaner. I'd scanned the forum for ideas before posting - I was really hoping that I didn't have Steve's problem - I had the valves adjusted just several thousand miles before and it had been running very nicely before its layup for the winter. Jeff pointed me in the right direction when I was hung up on it being an injection prolem. Learning of a competent and relatively local shop was just an added bonus - Thanks Mike!