If I could find one, I sure wouldn't have to post questions here (although the advice is top-notch, and I visit this site daily).

I have a 97 e320 with 115K miles. My problem is with just ONE spark plug that continues to foul (#5 plug). I have changed the spark plugs (now using the recommended Bosch FDC4), spark plug wires, coils, the connectors between the coils and the plugs, crankshaft position sensor, mass air flow sensor, and both oxygen sensors. I didn't mind putting all of these new parts on due to high number of miles already on the car, and I do get some jollies tinkering around with engines. After doing all of this, the aforementioned #5 plug continues to foul, although the check engine light is no longer on, and the performance (and idle) is somewhat better.

When I first start the engine in the morning, the idle is not steady. It seems to 'surge' and 'unsurge' until it gets up to operating temperature. The problem is most pronounced when I first shift the transmission into reverse from park. If I continue to hold the brake pedal down (have to have it pressed in order to shift into reverse), the engine lurks and spasms and acts like a wild horse that is being domesticated.

As mentioned in the title, if I could find a good technician in my area, I'd take it there and let them fix it. However, I've had this car to a competent indie, as well as to an authorized MB dealer. At least the indie was honest when he said 'I just can't find what's wrong with this car'. The MB shop just switched out the MAF and said 'Ok, your car is fixed. Come pick it up, and btw, please fork over $1,100 (new MAF and by inference, 10 hours of diagnostic time).

It certainly has been a frustrating experience trying to get this problem fixed. The car still looks new both inside and out, and I love driving it, especially out on the highway where I can set the cruise at 85 mph. No highway troopers in Iowa due to budget cuts....jk. The car almost drives itself.

Any ideas on what could be causing that #5 plug to foul?

Thanks in advance.....I like this site the best out of the 3 MB forums I read.

craig --

where in iowa are you from?

When my head gaskets needed to be done I went to Beckley's in Des Moines, best mechanic shop I've ever dealt with, very professional and honest, specializes in Europan Cars. They would probably be able to help you out. I've also heard good things about Duffey's in Iowa City, but I've never been there before.

Beckley Automotive Service
901 8th St, Des Moines, IA 50309
(515) 243-8185

Duffey's European Auto
525 south gate ave
Iowa City, Ia
319-338-0166


btw -- you're right about the troopers

John

__________________
1995 E320 119,000 miles

Wow!!!! More than 1 person from Iowa visiting the site lol......I live in Cedar Rapids - grew up in Bettendorf. There isn't a dealer here. in CR. I took the car to Lujack's in Davenport (biggest crooks in the world if you ask me)....as far as the indie, he is in Cedar Rapids. He used to work at a Bosch-certified shop in Iowa City (damned if I can remember the name, but it wasn't the one that you listed). The owner of that shop in Iowa City decided to pursue other interests, so he closed the place. That's when the indie guy now working in Cedar Rapids opened up his shop.

I do travel to Des Moines occassionally for work. If I haven't been able to solve the problem by the time I get to Des Moines again, I'll probably take the car there. As far as the shop that you mentioned in Iowa City, I've heard of him as well, but haven't heard any endorsements from anybody on these forums.

oooooooh, a Bulldog
I grew up a Muskie, which basically meant watching you guys trounce us in every single sport....

and yes, Lujacks are crooks, never went back there after they diagnosed and "fixed" a problem on my moms Benz as all 4 O2 sensors when it clearly wasn't

John

__________________
1995 E320 119,000 miles

If you are dropping one cyl., then look at that plug ..if it oil fouled , look for a bad valve seal.
For starters , I would do a compression test. Than you want to scope the ignition. That will tell you what is happening.
You mat also have a bad injector
Scope that too.

Is the plug fouled with oil or gas? What are the compresion test results?

Is the valve train quiet?

Oil fouling can be either bad valve stem seal (cheap, replace without taking head off) a valve guide loose in the head (cheap part possibly replace on the car), or a stuck (BG44 poured in cylinder to soak for a day)- or broken piston ring--mega$$. Fuel fouling is a bad fuel injector $150?.

[QUOTE=Kebowers]Is the plug fouled with oil or gas? What are the compresion test results?

Is the valve train quiet?

Need to know this.......but just from what you describe I think if its oil than valve stem seals, unless its fuel than a leaky fuel injector.

__________________
Juan Ramirez
Prts Mgr.
German Auto Center-SA, TX
jr67001@yahoo.com

My buddy has 78 450 sel w/ 30K original miles that fouls one plug and uses a lot of oil. Does the car run fine when the fouled plug is replaced or clean? Are you using a lot of oil? The 450 was and it turned out to be one bad valve seal.

It's gas fouled. The car burns absolutely no oil. Thank God for that. AMSOIL 10W40 is pretty good stuff.

I do plan on performing the compression check today. Its about time I use the tester that I have -)

What should be the proper compression?

also............if the problem does turn out to be a bad fuel injector, what is the proper procedure to replace one?

Replace With Copper Spark Plug