98 Turbo miss at idle - Page 2 - PeachParts Mercedes-Benz Forum

mdisav · #16 09-10-2007, 08:55 AM

Does anyone know if the shut off valve o-ring is the same as the fuel line o-rings?

nhdoc · #17 09-10-2007, 09:13 AM

Quote:

Originally Posted by mdisav

Does anyone know if the shut off valve o-ring is the same as the fuel line o-rings?

OM606.962 o-ring size

Most dealers stock them and they are about a buck or two.

mdisav · #18 09-10-2007, 09:57 AM

Thanks! I am off to the dealer.

nhdoc · #19 09-10-2007, 10:55 AM

Be sure to clean out the heads of the torx screws and seat a good quality bit deeply and snugly into them before attempting to remove...they are not very strong and many people including me have stripped the heads on them and it's a PITA to drill them out. You might even give them a tap with a small hammer before you try and loosen them to help them break free.

I replaced mine with good quality hex cap screws from Home Depot after that last fiasco. IIRC the size was M6 X 25mm.

92497pmu · #20 09-10-2007, 11:18 AM

mdisav

i've had the same problem intermittantly since i bought my car in 2004.
rough idle, see some of these posts

HARD idle

e300 rough idle? air leak? help?

98 E300 cold, low fuel, rocky idle

I've been frustrated almost to the point of selling the car sometimes.
It would be great if one of the old pros (help) MBDOC or others knew something and could chime in here...

I think I need to check the o-rings again & then it's probably injectors next.

Best of luck & keep me posted.

mdisav · #21 09-10-2007, 07:00 PM

Replaced the shutoff valve o-ring and it is still the same. But I still see air in the lines when I pull the throttle. Runs fine at full throttle. I put grease on the o-rings to help seal. Is it possible the lift pump is pulling air somehow?

Why only when warm and never cold and it goes away when put in drive or reverse????

mdisav · #22 09-11-2007, 09:17 AM

Also when the throttle is pulled it takes a bit to return to idle and stumbles like it idles. My 99 returns to idle immediately.

TMAllison · #23 09-11-2007, 01:03 PM

There is some (normal) flucuation when rpms decrease to idle levels due to the IFI leaning out the fuel mixture. Typically occurs somewhere between 1200 down to 700 rpm. Some cars do this more than others and some owners notice more than others. I notice mostly in stop and go driving in first gear.

mdisav · #24 09-11-2007, 03:46 PM

What is "IFI"?

mdisav · #25 09-16-2007, 01:47 PM

Replaced the shut off valve and all is well.

nhdoc · #26 09-16-2007, 03:56 PM

Quote:

Originally Posted by mdisav

Replaced the shut off valve and all is well.

Was the body of it cracked or damaged?? I have heard of them cracking over time.

mdisav · #27 09-17-2007, 07:48 AM

After replacing the lines I saw a lot of air coming from one of the line coming off the valve. So that is why I replaced it.

I have not inspected it thoroughly yet but I imagine so. There were no visible lines at 2 second glance. It is still in my trunk in my veggie scoop pot.

92497pmu · #28 09-20-2007, 12:12 PM

mdisav,

How are you coming with the rough idle?
did the new shutoff valve fix your issue?

Thanks for the update,
Phil

mdisav · #29 09-20-2007, 12:32 PM

Yes Phil, the shut off valve did fix the issue.