Lumpy idle - E34 V8

[myblack540i]

I'm trying not to jump to any conclusions without further analysis, but... my car has developed the dreaded "lumpy idle". I've got 152,xxx miles, and the Alusil block was changed at approx. 37K miles. I noticed it the other morning sitting at a stoplight. When the motor revs a little, it seems to run smooth and fine, but back to idle and it's very noticeable.

Here's what I think may be causing it. (fingers crossed) I noticed a couple of months ago when I changed my spark plugs that I had quite a bit of oil in the spark plug holes. Definitely need to replace valve cover gaskets as oil is seeping through.

Could there be enough oil collecting to possibly cause a short in one of the spark plugs?

Anything else that could be the cause?

[632 Regal]

you found it! thats the usua cause and if you leave it you can ruin the computer! you might want to change the plug boots out while your in there.

[DueyT]

Oh oh...now someone has Alusilitis!


j/k - Jeff's the man on this one...I take a look at the gaskets on a regular basis to make sure there's no leaking around plugs, etc...

Cheers,
Duey

[Johntee540]

Lumpy Idle is one of the symptoms of Oil seeping into the coilpacks. I just did Valve cover gaskets as preventitive maintenance. 2 coilpacks are more expensive than the overall job itself. Once these V-8's get this old this should be standard preventitive maint. - Jt

[632 Regal]

coilpacks, plug boots, injectors...havent done any gasket replacing yet though, no leaking yet.

[tim s]

a previous mech. abviously tried to just tighten the bolts to stop the leak & we ended up installing 2 heli coils & retapped 3 bolts for the valve cover covers.
tim s.

[jmccartney]

are you getting any CELs? Check the vacum hose - rear of manifold going into the Fuel Pressure Regulator, mine had a small hole that i did not dectect until i moved the insulation. If you are getting a 1221, check the O2 relay.