99 C280 Sport with 83,000 miles. The car had been throwing a check engine light for a little while and idling rough when cold. When I checked it I got the standard P0170 fuel trim malfunction code. I cleared it, and drove a few miles and the code popped up again. I cleaned the MAFS with MAFS specific cleaner and the problem was still there, code an all. I reset the system and the car got worse. Not only was the idle poor when cold, there was now a pause before acceleration would occur. If I push the gas pedal to leave from a stop, the car waits a full second or 2 before moving. If I'm already doing 45 and I punch it WOT, the car doesn't do anything for 2 seconds, and then it accelerates very slowly. At idle if I attempt to rev it, the delay is present. Stomp the pedal and a second or 2 later the engine would rev.

I replaced the MAFS and cleared the code. I took the car for a drive and it still had the delay before accel, and bad acceleration, but the code didn't return. The idle seemed to have improved, but the delay was still there. I turn the car off, then back on a minute later and the delay was gone. It revved fine at idle. I went for a test drive and the car ran great, had more power..... for about 5 miles, then it threw code P1542 and the delay came back. I get back home, turn the car off and instantly restart it and the delay is gone. I let it idle for about a minute, the CEL comes on again and the delay returns.

The code P1542 seems to correspond to the "Pedal Value Sensor" which I believe is what the throttle cable attaches to but I can't understand why this problem would suddenly start up. Even moving the arm the throttle cable attaches to by hand doesn't make a difference. Its plugged in nice and firm, I've removed the plug and reattached it to be sure. The air filter is spotless, the fuel filter has less than 4000 miles on it, the MAS is new, when the code stays off the car has plenty of power and accelerates beautifully. Unfortunately the code doesn't stay off for long, and sometimes it comes on while the car is idling.

This is a DANGEROUS problem since I can't pass anyone, I can't cross an intersection unless there are absolutely no cars within about 20 seconds of me, and if anyone ever comes flying up behind me at a stop, I can't get out of the way.

Has anyone seen this problem before or have any idea if it can be fixed easily or even if theres a way for me to test the sensor before just blindly replacing it since its rather expensive.

well, I had the experience where my old c230 1997 would not accelerate, and it was the mass air sensor, I know you have replaced it, however, let me tell You something...I own a 1998 c280 now, and there was a time that I replaced the sensor twice within a week, and at last I decided to clean the sensor very well, and that made it work...now, there is the pedal sensor that you are talking about, have You replaced it?....everytime you erase codes, the computer takes like 5 minutes to do a diagnosis, this is when it brings the error and its caused......

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предложения на е-мейл softforme@bk.ru

Hi, as you may already noted I'm new here.
In first steps it's very nice if somebody supports you, so hope to meet friendly and helpful people here. Let me know if I can help you.
Thanks and good luck everyone!

Hi, as you can see this is my first post here.
In first steps it is really good if somebody supports you, so hope to meet friendly and helpful people here. Let me know if I can help you.
Thanks and good luck everyone!