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A170 sometimes won't rev beyond 3000rpm

Greetings. New here, and looking for advice please.

I drive an A170 CDI. Sometimes it won't rev more than 3000rpm - actually about 2800 - and is a bit sluggish on acceleration too.Most of the time though, it is fine and revs and pulls freely.

This seems to happen especially when I have been idling for a period of time - like in slow moving traffic.

I have found that if I turn the car off for a few seconds, it seems to reset and the engine revs normally again.

It is as if the engine management gets stuck in 'idle' mode.

Can anyone suggest what the problem might be, and what could be done to fix it? Dirty sensor? Stuck airflow?

Many thanks

Derek

A170 sometimes won't rev beyond 3000rpm

I've had the same problem car won't rev beyond 3000 rpm, I've changed Air Mass Sensor, EGR Valve and Vacuum pump, if i turned car on and off its okay again for a short while.

I've taken it Mercesdes Dealer and 3 other independant garages I have had no joy. Can help or ideas would be much appreciated.

I have the same issue with my 96 s320 it will drive great for a while and without cause it won't accelerate from a stop I can put the pedel to the metal and it sputters and the trany shifts hard but I stop and turn it off I restart in a few seconds and it is normal for a spell anyway thanks

Quote:

Originally Posted by dale22 (Post 155909)

Hello Dale22 ~ My 95 S320 is the very same, has been doing this for nearly 2 years now! Have been through several shops, no one can tell me what the cause is. Being a woman, they all look at me as if I know nothing about cars, and as they cannot find the issue, I must be the one who is crazy! It was suggested in another forum that it may be a coil pack problem, but I have not had that changed yet, still trying to figure out with more conviction before I start nickle and diming it.

One thing I have tried is using octane additives to the gas, gives some relief for the immediate issue, but it always comes back again. If anyone here would have some suggestions, they would be greatly appreciated! Have 205K on her, would love to see 300 if I can :) Thanks!