Hi I have a 1999 CLK320 Coupe, I have been having a problem for some time where if I need to accelerate quickly and push the accelerator pedal to the floor or close to quickly the car dies, the car almost seems to go into limp home mode runs rough and can only reach minimum revs. If I stop the car turn off the ignition and back on it resets and it returns to a degree of driveability but with the same acceleration issues. Also from a standing start with only mild accelerator movement the car stutters a little and does not move off smoothly. My CLK is my only form of transport to work 100KM's away and it is not getting better. Note the symptoms are reproducable with the vehicle in park if you take the throttle to half way then max it out the engine seems strangled and does not increase rpm above 3000 even with the throttle wide open or rather accelerator maxed out.

I have changed the following items so far but am now at desperation point.
- Fuel pressure was measured at 10PSI at the fuel rail so a new fuel pump and filter were installed ( it was a cheap chinese guage that fell apart when I went to retest the pressure so I assume its fixed if there was ever a problem)
- Crankshaft and camshaft position sensors have both been changed all new plugs and airfilter.
- New TPS
I have changed oil/filter every 10000KM's with mobil 1 and generally the car has royal treatment!

I can rest the fault codes on the ECU and if driven carefully the car will not throw any codes, but if you hit the accelerator immediately you get every code known to man oxygen sensors, fuel trim, missfires etc etc.

If I run the engine at idle based on STFT the O2 sensors seem to be fine , the MAF responds as expected, every sensor on my scanner seems to be working together and engine is smooth but it can not accelerate rapidly without major trouble.

Could there be a vacuum leak pluged CAT's PLEASE Heeeelllppp

Have you tried unplugging the MAF and seeing if it improves?

If I unplug the MAF with car running it stops. if I try to start without the MAF plugged in it starts then dies.. I have ordered a new MAF but I think its probably ok??

Okay, this is sometimes the case when the you unplug the MAF but on some cars it will run okay just depends.

If your getting a MAF I would strongly recomend an original they are not that dear now, I've bought copies and they will fail quick. If your on a budget then get second hand original Bosch or Mercedes.

Does your code reader give you any errors on the 'hot film' sensor? this is related to the MAF.

Have you tried the throttle body position sensor?I had the same issues and it cured the problem It is by the windshield washer tank on my 2003 CLK 430.It is about $125.00 US to buy

Do you have any fuel trim numbers?

There were no malfunction messages but there a were a bunch is codes , sorry I do not know what they were..The sensor can be tested with a meter

......

At this point, you've probably thrown more $$ in parts at it than just getting it properly scanned at the dealer with the STAR computer. Normally $150 for 1 hour of "diagnostic" labor.

My first thoughts have already been done; Throttle position sensor, and CPS/KPS.

My CLK430 would idle with the MAF disconnected. It should go into a fail-safe mode and keep running.

Only other intuition I have is that maybe the cats are broken up and clogged.

Shot in the dark for you, but my 07 E350 had almost the same symptoms. Turned out to be a a bad valve body in the tranny. The actuators would get stuck cause the car to go into limp mode. The only difference is, my car would get stuck in 1st gear. Just a thought if you are having any shifting problems. GL

Engine ground cable, There is only one, It had better be in good condition. Otherwise think of your ECU having its brain reset or unloaded every time you start it! Its under the Drivers side motor mount.

Just hav a tought ...just get in the hood n go straight to the TPS sensor harness which will be located next to MAF sensor ..remove the battery negative terminal as usual n remove the harness from throttle sensor n clean it with some electric contact cleaner n socket it back firmly and reconnect the battery n give life to the engine see for any decent behaviour !! Gud luck

Just hav a tought ...just get in the hood n go straight to the TPS sensor harness which will be located next to MAF sensor ..remove the battery negative terminal as usual n remove the harness from throttle sensor n clean it with some electric contact cleaner n socket it back firmly and reconnect the battery n give life to the engine see for any decent behaviour !! Gud luck