Hey everyone, as most know my car is officially a 2002 CLK 55 now as Isis a complete swap a few monts ago. Everything has been running great until 3 weeks ago. I was driving and was behind a red light and the car just died. So I started it and it was very low power so took it to the shop and put a band new OEM Maf on and it fixed the problem as I was driving without a filter for a few months so maf was probably damaged. Ten two days later when I started the car it idled like a 57 chevy and finally when the check engine light came on I read the code and it said throttle postion sensor circut A malfunction, so I bought a brand new OEM position sensor and installed it and it was having the issues again so I bought a brand new oem throttle body and installed it with the seal. And then proceeded to install an E55 airbox with brand new filters for time being till I fan my intake. The car is running fine and has power how ever twice I stepped on the gas pedal while doing 15mph and the car hesitated for a second and then took off. So I did the throttle learning procedure and no issues sine. BUT and this is a nigh BUT(not the kind we like haha) sometimes when I start the car it idles pretty rough and car vibrates and also when I come to a full stop at the red light the car idles rough and shakes and then I put it in nutral and rev it a little and then put it in drive and all is good. I'm very confused as to what is causing it because everything on my car is brand new OEm parts, nothing after market. I have a brands new oem:
MAF
Throttle body and seal
Throttle position sensor
Vaccum hoses( all tight and new)
Plugs Bosch oem
Wires(Bosch oem)
Secondary high flow cats about three months old

Could this be caused by bad O2 sensors because they are used, I got them when I purchased my primary cats, they were in there but I don't think the car was high mileage. I'm really puzzled by this and any guidance would be much appreciated. By the way no codes or check engine light.

 

I had the almost the same problem when I have bigger throttle body and polish head. End up with bad fuel injector. And soak the spark plug wet all the time.

 

Hey dude! I haven't talked to you in awhile man, I see you are always doing crazy things with the CLK, last I heard you done a CLK63 bumper right? Is that still on there?

Well back to your prob, that sounds pretty hefty but I'm willing to bet it might actually be your Camshaft position sensor. I can't tell you where it is on the car because I don't know probably somewhere on the back of the block (Not to be confused with the Crankshaft Position Sensor which also sits behind the block) if it starts to go out it will retard your timing and the car will start to feel like it's a diesel and feeling all clunky and sound different.
OR
Your timing may be off and may be due for a timing chain.
OR
It may be your fuel pump going out, but it actually could be a number of things but first place to start is your spark plugs and make sure they are getting spark, your ignition coils, then re-check your MAF, and definitely check the Crankshaft Position Sensor which is relatively cheap to get.
It sounds electrical related. Hope that points you in the right direction.

OH and almost forgot, do what tery said check fuel injectors and your Fuel pressure.

 

My MAF, plugs and wires are brand new. I have 3 brand new oem MAFs and tried all of them and no difference so I can confidently rule that out, the camshaft position sensor I honestly didn't know of so that is the one that came with the motor. Fuel pump and fuel filter are brand new as well and I get perfect fuel pressure. I forgot to mention that two weeks ago I was driving around 20mphs up hill and I floored the pedal and it down shifted and took off and then boom it died and wouldn't start, so I checked everything and all was well and found out my ignition coil fuse( the fuse box inside the engine compartment) had blown so I switched it out for a new one and right away it fired up.

 

https://www.autohausaz.com/search/pr...rk%20%20Sensor
That's for a 02 CLK55 motor.

But honestly sounds like you are also having electrical issues, check your wiring harness and bust out the multimeter and start some tests. If you are blowing your ignition coil fuse it'll happen again if you got a short somewhere.

Try the sensor route if you think that may be the problem.

and if you don't want to buy a new sensor, test out the voltage input and output.

 

The fuse thing only happened once and my mechanic who is a Benz mechanic said he has seen it happen before as an isolated incident when the car is too hot or something, but honestly te fuse thing happens two weeks ago and I've been using and abusing the car since an no issues, it has full power and runs fantastic, if I can just figure out why it idles ruf at idle sometimes and wen I come to a quick stop, that will be the end of any issues I'm having. I did do a search and the cam shaft sensor sits in front of the head on the passenger side and it is easily accessible, do you think that might have anything to do with it? Because I replaced all the other sensors except that and the knock sensors when I did te swap. And the motor has extremely low miles but was sitting for 6 years before it went into my car, therefor I change all the seals and gaskets and sensors and water pump..... The only two thins I didn't chane where the knock sensors and the cam shaft sensor.

 

Hmm, interesting. Well look at the Camshaft Sensor and if you see oil deposits around itself, that could also be a good indicator that it's done and needs a swap. As for the knock sensor that is also a good direction to go in. One little sensor will throw off the entire driving experience. But you say it has low miles and been sitting for 6 years so I don't see how any sensors would go bad sitting without use.. but it may have already been on it's way out..

During the sit did you do anything else to the motor?

 

Drive the car all day an all was great, I got home parked te car for two hours and just went down to start it to leave and right when I started it started woom woom woom like some one is playing with the throttle and the check engine light kept flashing, **** it off and re started an same thing, shut it off the third time and restart it and same thing and this time it died, shut it off and start it the 4th time and idles and works perfectly normal! And no check engine light or anything. Something is wrong with this thing.

 

Yeah you got some crazy stuff going on, more complex than sensors I mean the symptoms it's giving off sounds like Crankshaft Position Sensor AND a Camshaft Sensor.. but it's hard to say with everything you got going, it sounds more like wiring issues, did you do the swap yourself or someone else do the wiring, check the wiring and connections and they are in the right places. Let me know how things go.