Once again...'86 280i

[Grady]

I'm still getting a sticky goo on the mixture plate (right name? - the thingie under the round rubber cover that measures air into the FI system). As a result, starting an 850 (warmed up) idle, the engine begins to chug and the idle gets slower and slower, going into a death spiral then dies (unless revved) over about 15-20 seconds. Clean it with a blast of carb cleaner and it's good for a couple of weeks, idles smoothly at 850.

Where is this gunk coming from? The air filter using is clean, the housing is clean, the recycling hose(on the outside of the filter) is clean.

I'm only suppose to be dealing with air though that section of the FI system, right? So why the Chinese restaurant grease????

Thanks Grady

[mrzigazaga]

Hi Mate..It sounds like the only thing making it gum up is fuel..Perhaps fuel vapour?..Return fuel pressure?..Ziga

[ROOODBOY]

What air filter are you using?

I've heard of this happening when oil-impegnated filters such as K&N are over-oiled after cleaning.

[Grady]

It a K&N but not over-oiled (in fact it's clean but I can't remember when I last cleaned & oiled it). And the grease is brown not red.

The odd thing is there is no sign of anything oily/greasy on any of the bits upstream (or down-stream for that matter) of the plate.

Am I wrong that the only only things that pass around the plate are fresh air via the filter and whatever comes from the return vent line that goes in to the air box?

[mrzigazaga]

Hi Mate..Have a little read..It could be your pressure regulator, This site requires that you download a file..Mainly for protection..Once the file has downloaded just open it or save it if you want..I have it saved if you want me to email it..Cheers..Ziga
http://www.google.co.uk/url?sa=t&rct=j&q=b...

[jeff m2]

Ok, off the top of my head no real thought behind this (as always)

Check your upper and lower crankcase pressure. (make sure they are clear),basically hoses and a brillo pad.

Valve stems ?

Hose from the emissions canister chucking in crap.

ETA Maybe deal with the initial problem first. The bad idle.
Get some fuel cleaner through your system, either Techron in the tank, or if you have a buddy with a fuel system cleaner, they are magic.

Edited by jeff m2 on Thursday 27th October 18:08