Hey everyone. Question for you.

For the last year and a half or so (since I've owned this car), I've had hesitation problems. Since I bought it, I've done all of the regular W124 maintenance (head gasket, etc). I've had so much stuff replaced that I can't remember it all, but it rings in at over $7k (OUCH!). Included in that list of repairs is a new set of injectors roughly 6k miles ago. I've had the plugs, wires, rotor, an ignition coil, O2 sensor, fuel distributor, head gasket and valve job, done.

These repairs were done over the course of maybe 5 visits to the shop. I tell the mechanic each time that I have a hesitation problem, and for the first 200 miles or so after I get the car back, it's smooth as silk. Then it slowly goes back to hesitating pretty badly when I accelerate (most noticeably from a stop).

Yesterday when I gassed up, I put in some fuel additive stuff and some injector cleaner. I figured I might as well give it a try... Almost right away, my hesitation problem was gone. I remember that my mechanic said he's cleaned the injectors before. So I got to thinking, I wonder if the car just runs fine for a while after I get it back because the injectors are clean, then somehow they get gunked up again. If that's true, then something is causing my virtually new injectors to get clogged.

I was directed to mercedesshop by another member at the bnzsport forum. I tried to do a search on carbon deposits (as he directed), but have had a hard time finding exactly what would help me. I'm not interested in cleaning the injectors as much as I'm interested in finding what's causing it...

Any help would be great. Thanks!

Peter

This is probably the help you need.

http://www.toptiergas.com/

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Kent Christensen
Albuquerque
'07 GL320CDI, '10 CL550. '01 Porsche Boxster
Two BMW motorcycles

Thanks for your reply. I looked through that website, and it seems like good advice. However, I only buy my gasoline from Chevron and Shell (which are listed as "top tier" retailers).

The problem is, my car had the injectors replaced 6k miles ago (about). I can't imagine that gasoline would cause this problem after 6k miles, even if it was unclean gas. But again, I only use Chevron and Shell...

I should also note that I only use high-octane gas, and the previous owner (my sister) has too... I haven't put a drop of low-octane in my car.

Maybe there is a bad fuel filter on this car or crud in the tank that the filter is passing.

yeah, that's a good point. By logic, it doesn't seem like only dirty gas and a dirty fuel filter could be causing a problem after only like 200 miles of driving after tune-ups. There must be something else, so a cruddy gas tank coupled with a bad fuel filter could be the culprit.

How would a guy figure out if his gas tank is nasty? And if it's nasty, how do I get it cleaned? Do you just drop the tank and hose the sucker out, or what?

Thanks!