I cleaned the Idle control valve today but --

[allan]

my idle is still not stable. The valve was rather gunged up and I really thought that this was the problem. However I cleaned it until it is perfectly free only to find that my idle speed is still not completely stable all of the time. The fault seems to be an intermittent one because sometimes things are fine and the engine idles sweetly. Then when I stop at the lights again I feel a slight shudder as if one or more cylinders are mis-firing. Why would it come and go like this ? Someone suggested changing the spark plug insulating boots ? I have cleaned them and they look fine as do the plugs themselves but I wonder if new ones would cure the problem, can the rubbers be bought seperate from the coils ? Maybe I should I be paying for a computer diagnosis ? Any suggestions please ?

[western99]

my idle is still not stable. The valve was rather gunged up and I really thought that this was the problem. However I cleaned it until it is perfectly free only to find that my idle speed is still not completely stable all of the time. The fault seems to be an intermittent one because sometimes things are fine and the engine idles sweetly. Then when I stop at the lights again I feel a slight shudder as if one or more cylinders are mis-firing. Why would it come and go like this ? Someone suggested changing the spark plug insulating boots ? I have cleaned them and they look fine as do the plugs themselves but I wonder if new ones would cure the problem, can the rubbers be bought seperate from the coils ? Maybe I should I be paying for a computer diagnosis ? Any suggestions please ?

A couple of other things that could potentially affect your idle is your throttle position sensor and your air flow sensor. Take a look at these. I have had these things in the past make my idle very rough. Just a suggestion.

Brian

[allan]

My car is a 1994 530

[KenB]

I had a similar problem that felt like slight missing and the idle would vary once in awhile (also very slightly). Tried new spark plugs, it ran like new...for a few days. Then it started over again, a little different but I could tell it wasn't 100%. I started thinking about spark plug wires, etc. Tried injector cleaner thinking it was a fuel problem. Never got a check engine light and no codes were stored when I did the stomp test. Could hear a different note from the exhaust, sounded deeper, performance wasn't smooth as silk all the time, as it should be. Finally put 6 new coils in, OK for a few days. This has been over a period of the last year since I bought the car. Most of the time it was fine, then it would run funky for a bit, it was driving me NUTS!!! Finally, somebody asked if I used Di-electric(?) grease on the connectors. Well, uh no, I didn't. Went to Pep boys last Saturday and sprung for a tube, a big $3.00!! Took the coils and connectors off and put a dab in each end of the connector.
What a difference. Idle steady and smooth, performance A-1. Now I can REALLY feel the difference that the EAT chip makes. Makes me wonder if my coils weren't bad to begin with but with 130,000 miles, I figured they could stand to be replaced anyway.

I had never heard this grease mentioned by anyone before, or I was not paying attention when they did. A BIG difference for a little bit of time and money. Try it before you spend money on anything else.

If your connectors are real dry or cracked, they can be replaced separately, they are available from BMA for $5.26 each. I didn't replace mine with the coils but they looked fine.

Good luck!

[winfred]

did you clean the throttle body they can get cruddy also, if you absolutely can't figure out the problem id suggest changing the intake manifold gaskets, throttle body gasket and the pcv plate, we are getting to the point every v8 that comes in the shop with a running problem gets it's intake system sealed up and it's cats checked for being plugged, we got bit in the ass by 3 e38s in a row, all pcv plates and or cats, all running bad in a totally different way, we've seen 4 or 5 different ways that the intake system can screw with the running and only about half throw a code and trigger a ce light