Rough idle in park 1991 R129 - PeachParts Mercedes-Benz Forum

pollockd17 · #1 09-13-2006, 08:04 PM

My 500SL has an excellant idle while in gear, 600RPM but in neut. or park
it is a bit lumpy. My injectors are new as are the ignition components,cap
rotor plugs and wires any thoughts on this condition??????

waybomb · #2 09-13-2006, 09:35 PM

That car just wants to go. Leave it in gear and go It has a type "A" personality!

Sorry

I have no idea, but I am very interested in learning what could cause this.

LeaUK · #3 09-14-2006, 05:24 PM

did you change the distrib caps too?

pollockd17 · #4 09-14-2006, 08:09 PM

Quote:

Originally Posted by LeaUK

did you change the distrib caps too?

Yes I did, everything electrical was replaced

RSWoodley · #5 09-15-2006, 08:03 AM

I had SEVERE problems with the new fuel, when they switch to Ethanol mix. I read in my boating information to use a good quality gas line antifreeze every second tank until they got the mixture just right. I did this in my car. I ran that twice and the car started to smooth out. (This after replacing first plugs, then wires and finally the coils) . Apparently when they first started with the ethanol the mix was not right and they had to experiment with it. High performance cars where the worst effected however my wifes Murano was hit too. What happened was the gas when burned left a very light white residue. This made the vehicle run rough, in my case VERY rough at idle. The gas line antifreeze clears it out. I know this sounds a little funny but it is true.
I found that mystery oil works the best even though it is not an antifreeze it cleared everything up and the car runs PERFECT.

1995 SL320

miles · #6 11-23-2006, 03:36 PM

I had this very same problem. Found to be the fuel pumps (2 pumps by the tank). The pumps were both working but the pressure they were ment to perform at was below specification. Both replaced - problem fixed.
Hope this helps.