Hi Folks,

I'm in a pickle and hope someone can help. I have a E320 2001 wagon with 160k miles on it.

Its had pretty normal oil changes, transmission oil & filter change at about 120k miles, diff oil change etc.

Recently it had new spark plugs and alternator and battery.

I regularly clean the maf sensor with proper maf spray. I also tried putting the parking brake on and leaving the car in drive, giving it a little gas to load up the engine, the motor didn't seem to move too much in the bay so I think the mounts are ok.

Could it be a coil pack? I'm not sure about this because it runs great and the fuel usage is normal.

The problem is somewhere around 157k miles it developed this odd kind of mis- fire at idle. The idle speed is very solid and doesn't fluctuate up and down, it just kind of misses and the engine idle is 'lumpy'. There is no rattling in the engine or noises, no check engine lights. The car gets good gas mileage (for this type of car) and runs perfect, the gears shift smoothly and normal.

We did take the car to a good mechanic, he replaced the alternator and battery (we knew the battery was pretty dead) and he put new spark plugs in (we didn't know when they were done last).

He did pull the engine cam covers and he claimed the chain has too much play and recommended putting in a new chain and all tensioners. He asked for $4k for the work which seemed really expensive. I did some searching online and most people think the chain rarely stretches or needs replacing, so I doubtful this is the problem.

I did pull the spring/plunger tensioner to check it a week ago, it seems in good shape, so this part seems good.

Can anyone help? I'm wondering if it is a clogged EGR valve or something. Would seafoam help?
Could it be air leaks upsetting the idle? are there known areas on the V6 that leak air?

I am a mechanical engineer so fixing it within reason is something I can do.

Thanks for all the help

Chris

P.S. Here is a video of my car engine issue:

Engine idle - YouTube

__________________
Current Rides:

2004 BMW R1150GS Adventure
2005 MB W211 E320 Cdi

Just because you clean the MAF doesn't mean it's good. I suggest replacing the MAF. It can do crazy things. Start with that first. It's a cheap part.

I agree on the MAF. A friend is on his 3rd one on a 2002 E320. Symptoms were rough idle.

DG

In video - are you on Drive or Parking?