Thanks David, actually last night I pulled the plugs - sure enough they were "carbonized" - very thick. I cleaned them off the best I could, replaced them and noticed a much better improvement - I am going to pickup a new set today and replace, hopefully this will solve the 3000 rpm problem.

It sounds like the Italian tuneup is very similar to the Hungarian tuneup! Will do - thanks again.

Back Again! OK - we are sure now that I don't have a tranny problem, I have replaced the spark plugs, increased octane, added the Chevron fuel additive. Anytime, in neutral or driving, if the engine (tach reading) goes above 3,000 rpms it drops back down and will not go higher. The engine idles fine, It drives real well (even with AC on) unless I exceed 3,000 rpms (this means I slowly accelerate and can only top out at 65mph on the highway). I've looked for loose vac lines - but I am not sure where they all are. What is a puzzle, is this 3,000 rpm limit - it doesn't matter if I am in neutral, accelerating, or just driving down the highway, it happens at the same spot???

Does it happen at 3,000 rpm and above... or just at and close to 3,000 RPMs? Is 4,000 RPM ok?

__________________
2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)

David, I can't get above about 3,200 rpms at all! If I sit in neutral and hold it down it just revs to 3,200 max ( then it backs off to about 2,900 and increases to 3,200) it kinds of oscillates there. While on the road, I generally will accelerate slowly to allow the trans to shift and slowly build speed. If a try to accelerate too fast and exceed the 3,000 rpm limit it shifts - but it is pretty ugly. I can slowly accelerate with normal shifting of the tranny until I get to about 65 mph - that is where the rpms reach above the 3,000 rpm level, if I try to go faster it acts like it governs the speed and rpms.

Thanks

Indeed, your problem may be stemming from other issues. Did you have a recent and decent tune-up? Did you put Redline sythetic oil in the tranny and rear dif? New tranny filter and gasket? Explore the cheaper fixes like fluids and plugs, cap, rotor, wires, etc. I know you must be frustrated at this point and $1000+ in lost coin and your babey still isn't right. My sympathies, brother. May the automotive gods shine brightly on you.

Jim
1992 500E

If all you can get is 3200 RPM out of the engine in neutral, this is an engine problem not a transmission problem. Look for horses, not zebras when you hear hoofbeats. Since you had a bad carbon deposit problem on your plugs, you might look for either valves that are adjusted way out of spec., or possibly timing also way out. How many miles on the car? Has anyone adjusted the engine lately? Were the plugs the right ones or were they way off in the heat range? Any possibility of fouled fuel? Something is simply not right here! Go through the various possibilities in a logical manner and you will get an engine that runs correctly, then work on the transmission.

__________________
'76 240D-Sold
'78 240D-Sold
'85 300 SD, 165K-Sold
'88 300 TE, 165K-Sold
'64 Porsche 356C Cabriolet- under restoration
'86 560SL 124K Miles-Sold
'94 320E Wagon, 74K Miles-128K Miles JUNKED
'06 E350 Wagon, 84K Miles
07 SL550, 14K Miles

I would put it into first gear, and then just try and get it up past 3,000 slowly... but then again, if it runs really rough, I wouldn't want to hurt it.
I agree with Jim on trying to get the cheaper fixes first... maybe you could try some of the X66 stuff (recent discussions on it) and see what happens if you still believe it's carbon build up... but carbon build up should slowly burn away the more you get the revs up... seems weird. Try a bottle of Techron also... what gas are you using? Good luck.

__________________
2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)

Thanks all for the help. The funny thing with this, other then the limit of 3,000-3,200 rpms is the car seems to be running well. The engine is quiet (not pinging), the tranny shifts a little rough (from other threads, this may be normal or could be improved with some adjustments). I use octane greater then 91, I am running tectron through the system.

I do have a local tech that I am going to take it to. I was hoping that others may have experienced this also. Anyway, I will follow-up on the cause for future reference after the tech gets done bilking my bank account.

Sounds a lot like a plugged exhaust (catalytic convertor).

__________________
Steve Brotherton
Continental Imports
Gainesville FL
Bosch Master, ASE Master, L1
33 years MB technician

Well, let me update you all! If you remember, I was having an acceleration problem - I could not go beyond 3200rpms (Drive, Neutral, or Park). Here is what was done.

7. Checked Catalytic Conv. - back pressure test and with it totally removed. (did not solve - conv. ok)

6. Checked Plugs - some carbon build-up, replaced (did not solve)

5. Checked and cleaned Distributor (did not solve)

4. Cleaned and checked injectors (did not solve)

3. Cleaned and checked Fuel Distributor (did not solve)

2. checked all vacuum connections (all in tack)

1. Replace Fuel Pump Relay - BINGO!!!

Evidently, the relay switch had some sort of govenor (sp) that went bad - the tech was not sure why there was a govenor (sp) on the switch - but it was there. Anyway, thanks for all your help and I hope this saves others some time and $$$$.

Wellington,
I'm glad you finally solved your problem. WHat a relief! It seems as though your rev-limiter wasn't working properly, it's supposed to prevent higher revs at about 6,000 RPM, not 3,200!
Well I'm glad your problem is solved. :p

__________________
2006 E350 w/ 155k miles (Daily Driver)

Previous:
1993 300E 3.2L Sedan w/ close to about 300k miles
2003 E500 Brilliant Silver (Had 217k miles when totalled!)
1989 300E with 289,000 miles (had for <1 yr while in HI)
03 CLK 500 cabrio (Mom's)
2006 C230k (Dad's)
1999 S420 (Mom's/Dad's)
2000 C230k Sport sedans
2001 CLK320 Cabrio (Mom's)
1995 C280 My First Mercedes-Benz... (155k miles. EXCEPTIONAL AUTOMOBILE. Was Very hard to let go of!)

Thanks David,

I had the opportunity to participate with the tech during the search. This forum helped a lot with the process. The tech was very knowledgeable, but didn't mind my suggestions etc. His smile was as big as mine when we localized the problem.