<E28> strange thing at start.

["Ron J" <ron@xxxxxxxxxxxxxxx>]

Hi All,

Recently, this strange thing started to happen when I start my 85 535i.
Usually when the engine is cold.  I start it and it idles high for a sec,
like normal, and then starts idling really rough about 10 seconds in.  If
you give it gas, it runs rough up into the higher RPMS, and blows a lot of
smoke out of the tail pipe.  You can also smell the unburnt gas from the
exhaust, and when you drive the car you get backfireing, which tells me that
there is unburnt feul in the exhaust system.  I am thinking it isnt a bad
spark problem since the issue pretty well goes away as soon as the car is
warm.  I suspect its the feul pressure regulator, most likely feeding too
much feul to the engine at idle, and since the car is cold and at low rpm it
cant burn it all.  Once you step on the gas and bring it into high RPM it
steadys out since it is getting close to the right pressure, and can burn
all the fuel.  I would suppose that once the car is warm, it can burn the
feul more efficiently and the idle evens out.  I did notice a little bit of
jerkyness even when the car is warm, when I am driving at lower rpm (when
warm) and I let off the gas or get back on it.  Like its stuck in higher
rpm.

I am going to order a new FPR but I wanted to get some other opinions before
I do.

Cheers
Ron J
85 535i
73 911s 2.7

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