I have a 2008 C300 sports flex fuel throwing code p0170 and p0173
Replaced MAF, MAP sensors, spark plugs, all 4 o2 sensors, vacuum lines,intake manifold air filters, intake manifold actuator. Qhat else is there to fix this problem? Please let me know is it dirty fuel filter, fuel pump, fuel injectors? Causing it?

moved to W204 forum...

HI, did you get to fix it? Mine is throwing up the same codes and is misfiring at idle - unsteady idle. But above 2000 rpm seems to be driving fine unless power limited due to the misfires.

What have you tried fixing? Start at the MAF. Use Bosch.

I replaced the intake manifold, It had a stuck flap in the manifold (infact the vacuum actuator linkage to the flap was broken - at the joint and not the vaccum unit to the swivel connection). I completed the work on Sunday and restarted the car - it was still misfiring at idle. Yesterday I went and checked the codes at Autozone - it is showing up another code 2015 intake manifold performance. However the P0170 and P0173 are not there for some reason.

However I have the P0300 code - Random misfires. But it is occuring only at idle. I have had the P0017 and P0016 for about 90K miles ( cam crank syncronisation error).. However the engine runs fine at higher rpms and doesnt seem to be doing any different than before - power seems to be the same as before. So I am suspecting it is some vaccum tube or MAF sensor. Next is to get a MAF sensor. Saw one at Rockauto from Bosch. Hope to get one and see what it does. If that doesnt fix it - wondering what it might be.

Did you ever replace the cam and/or crank sensor?

Quit going to auto parts stores and get your own MB scanner! Here's an excellent choice!

So previously you were getting codes P0170 and P0173, replaced the intake manifold due to broken linkage. Fixed those codes but now its showing P2015 and also P0300.

What engine do you have?

What brand intake manifold did you install?

Because you say you recently replaced the intake manifold and now have code P2015 I would go back thru the installation and make sure everything is connected properly. Check all the sensor connectors and vacuum lines.

The code P0300 could be spark plugs, O2 sensors, coil pack, blocked cats, clogged fuel filter etc. At least from what I come up with upon searching that code.

I would check the fuel pressure, may tell you if its fuel related.

​​"I have had the P0017 and P0016 for about 90K miles ( cam crank syncronisation errors) - However the engine runs fine at higher rpms...."

This is your loose VVT-Gears saying goodbye nicely.

I would not bother with a new MAF to fix that.


Make sure you're running clean engine oil/filter to remove wear metals.

I replaced the sensors and also the cam solenoids. Did not do anything to the codes.

In addition to p0300 there are misfires on all cyclinders - i e it shows cycl 1 through 6. I installed a part I received from Amazon - it says Miliparts.

I will check the connectors and vacuum hoses over the weekend just to ensure that I have not missed anything.

If it was fuel pressure related or filter related, I would think the performance at higher speeds would be impacted. I do not feel anything is down if the engine has not gone into a derate mode if I stay too long at idle. However the derate will go away if i switch off and restart until it has time to detect in idle area.

Really need a proper scan tool to clearly understand what the issue is. In the mean time I have ordered a MAF sensor from Autozone - a Bosch one. I can at least check out. I am suspecting since all the cylinders are misfiring at random, it has to do with some thing to do with air.

I have run 90k miles with p0017 and p0016. It originally popped up above 100k miles. Now it is around 188K miles. The misfires are probably not related to it. Originally there was P2004 which was to indicate the manifold flap stuck open. I also had P0170 and P0173. I replaced the manifold. The thought process was if the manifold has issues this would cause misfires. After replacing the manifold I am getting P2015 - intake manifold performance. Not sure if the P0170 and 173 will reappear after driving for some time or not..

right now ordered a MAF sensor to check out if that is the cause for misfire. It occurs at idle and above idle seems to be driving fine.

[QUOTE=

What engine do you have?

Missed to reply on the engine

It is a C300 sport 2008. It has the M272 - the models before 2008 had issues with crank pulley wearing off and it was a class action lawsuit against mercedes for dead engines. this one has a fix supposedly.

[QUOTE=vijujohn@gmx.at;8985572][QUOTE=

What engine do you have?

Missed to reply on the engine

It is a C300 sport 2008. It has the M272 - the models before 2008 had issues with crank pulley wearing off and it was a class action lawsuit against mercedes for dead engines. this one has a fix supposedly.[/QUOTE]

wait.... a M272 2008:
isn't "balance shaft" involved here?

We're trying to help you sort things out here...
You should not ignore timing errors when searching for misfires.

That why I suggest focusing on your "cam-crank correlation".

The ECU is unable to burn well and leaning trims out negatively. The result is low power slow poke hot engine to prevent air pollution.

Thanks Cali for helping out. Appreciate very much your input.

I do understand that timing cannot be ignored. The question is for over 90k milesI had the same error with no appreciable difference in performance ( I had a mechanic who used to work at Mercedes benz dealership and he scanned it some years back and said that I have to replace the chain. However I am suspecting that even if the chain was replaced the error would have been there. I am suspecting the VVT mechanism ). Even now if I accelerate hard - I do not find an appreciable difference in performance. The issue is rough idling. It is not misfiring at higher speeds or at least there is no uneven feel or vibration above say 1200 rpm.

If it is purely a Cam sensor issue or crank sensor issue - I would have thought it would show up all over the place unless and until engine is running with an assumed timing position based on one of the sensors.

A "correlation code" is the ECU saying your camshafts are loosely positioned.
This screws up the timing of both injection and ignition = lean misfires.

What can cause that is either: VVT, Tensioner, (Chain)... sorted in decreasing order.

You can inspect these items by manually rotating the crank pulley to align timing marks.


Happy troubleshooting....

Thanks Cali

Do you by chance have pictures of the timing marks locations on the crank and the cams?

The logic for me for not suspecting this error code ie P0017 and P0016 is because I have had it for almost 90 K miles . The misfires started only recently with P0300, P0301 to 306 .P0170 and P0173 also the P2004 Intake manifold actuator stuck open. That is when I took out the manifold and replaced with a new one. The one on the car had the connection between the outside to the inside of the flap was broken. After fitting the new one, I still have misfires at idle and has the P0300, P0301 to 306 ie random misfires and another code P2015 (intake manifold performance). The P0170 and P0173 codes have still not come up. May be a little more extra driving - not sure if it will pop up.or not.

Air filters are not that old. I hope this will give a better explanation on the logic of trying out a different MAF sensor. If the MAF sensor doesnt fix it - as you said it could be timing, lambda sensor, catalyst, throttle ( I read in another thread someone had an issue with the throttle wiring - mine had the external plastic insulation cut - however the wiring was not rubbing or I could see any copper on the throttle). So I suspect it is not throttle body.. Also if it were catalyst the engine performance would have degraded significantly - which I am not feeling when accelerating hard.

In any case MAF sensor come out tomorrow and will try out this weekend. Thanks once again

You may be wasting your money if the MAF is not the problem. Misfires at idle can certainly be a vacuum problem.

There are four things you need for combustion: fuel, air, spark (timing), and compression. If your cam solenoids are failing (as Cali hinted), you may not be getting proper compression. Cancel the order with Autozone, save some money, get a scan tool, and if it indicates a bad MAF, get it from RockAuto.com. The Bosch one is $74.

https://www.rockauto.com/en/catalog/...f)+sensor,5128

These cars loves good parts. The parts-canon is not a bad practice! It will get you there but cost more. Make sure you trust the quality of replacement supplies, not eBay genuine-fakes.

The MAF, the intake plenum, coils, plugs, boots, (injectors), filters, (pumps), upstream lambda, (downstream O2).... must go anyway.

Check fuel pressure, fuel trims and ALT Voltage. It's free and will helps guide your repairs.


Cam timings needs to be ridiculously predictable, so chain TENSIONERS are excellent items to replace (beside loose VVT gears after testing).
🤞

Post 17 you mention wiring insulation being cut. I would wrap it up with some electrical tape just to be sure.

Air filters you can visually tell if they need to be replaced. Maintenance manual says replace every 4yrs/40,000 miles so they do last awhile.

Thanks Cali.

I did tape the wire for the throttle. I hope I did not miss anything on that wiring - If the throttle wiring has issue also this could cause or?

For the timing it looks like I have to take the cover off the front of the VVT - correct?

Thanks once again.

I don't know anything about throttle issues. This is usually out of reach for chaos. It limp-mode in a blink.... rarely.

If you have CPS located on top of valve cover then you have access to see the top of VVT-gears simply by pulling CPS out. There are few YT about that check.
Rotate only clockwise.

Thanks Tim. Will take a look if I can check the timing. I thought I replied to you. But I had adressed my message to Cali (both of you have been responding to my messages).. Thanks once again . Will keep you guys posed.

Thanks Cali. Will try to check and see. Will keep you posted.

HI Jetta Red, I had tried out MAF and it did not do anything. I will be returning the MAF back. Also looked for visible leaks on vaccum lines. Couldnt find any. One of my friend had a better scanner and he was suggesting looking for vaccum leaks with smoke.

I checked the codes again. Today I had P2006 and P300 - random misfire codes P301 -306 - but P2015 has disappeared. Makes me think there is some vacuum leak that I have not figured out yet.

Will update once I have had the scan with my friends device and do a smoke test.

Thanks once again.