re: E30 Rough idle (long)

[XXX <JMK8014@xxxxxxxxxxxxxxxxxx>]

John,
	Since you asked, a poor and somewhat lopey idle can be caused by a myriad of things.  Trust me, I've spent enough time
weeping and gnashing my teeth at the altar in the Church of Idle.  A valve adjustment can solve your tappety-bappety when the M20
engine is idling at 800-900 rpms, and acts as an acid test to see if you need more work.  BMW engines need to have the valves
adjusted every 25k or so after you hit the first 100K miles.  But if you have a lopey idle that jumps up and down, check other
things like the timing belt, cap and rotor, spark plugs, plug wires, and drain a bottle of some cheap STP carb/fuel injection
cleaner in the gas tank to loosen up anything that might have gotten clogged.  
	Also, something most people overlook: the owner's manual says very specifically that eta engines like yours and mine can
suffer from carbon buildup if driven too conservatively for long periods of time.  And you know it says to solve this problem??? 
By periodically driving at 4k+ RPMS to knock all those nasty carbon bits outta the system!  It gets even better with a 2.71 gear
ratio too!!  "Oh, uh sorry officer, I had to speed in order to clean up the engine.  It's good for the car.  Really, trust me."
	So, to sum, there are a lot of factors that can affect the idle on an ETA engine, but it's usually due to one of the things
mentioned to this point.  Anything else is usually more expensive, like a new DME or in my case, a few bad cam lobes after a blown
head gasket.  YMMV,
	Joe Kramlinger
	Rochester, NY
	'85 528e

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