P0172 System Too Rich - 2002 C230k coupe auto
10-17-2016, 10:36 AM
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2003 C200 Kompressor
P0172 System Too Rich - 2002 C230k coupe auto
Hi
So I have brought this car back from the dead and had a blown head gasket repaired. It's got new pistons, piston rings, big end bearings, head gasket and aftermarket MAF sensor.
The mechanic who did the job for me returned the car. It's running great, plenty of power, but uses plenty of fuel also. The check engine light is on.
Fuel consumption is 13.5 - 14.5 l/100km
What I have done so far is the following:
Initially LTFT was -15%
I replaced the MAF sensor with the original which I repaired (the electronics had come off the body so I plastic welded it back). No change in performance, still runs good, and LTFT moved to -10%
I don't want to start changing parts in the hope that somehow the problem will go away, so I would rather diagnose the fault.
Apparently the injectors were checked according to the mech.
For a rich code, the following come up as suggestions:
MAF sensor overreading - unlikely since both MAFS did the same thing and dirty MAF's tend to underread.
Fuel pressure too high - unlikely since the fuel filter has an integrated pressure regulator and it's an original part.
Dirty injectors - injectors apparently checked.
Faulty MAP sensor - I've checked the ambient but not the manifold one.
Faulty O2 sensor - O2 story below.
No hesitation on acceleration, great idle, the car runs really good.
I've plugged in my diagnostic tool and after a 20 minute trip the following are parameters are I've recorded.
Pre cat O2 sensor, voltage bouncing between 0.1 and 0.8 volts.
Post cat O2 sensor 0.85 volts - this seems a bit high to me?
Where to from here?
Ideally, what should a healthy post cat voltage reading be?
I'll A/B against my 2003 C200k and report back.
Suggestions welcome.
So I have brought this car back from the dead and had a blown head gasket repaired. It's got new pistons, piston rings, big end bearings, head gasket and aftermarket MAF sensor.
The mechanic who did the job for me returned the car. It's running great, plenty of power, but uses plenty of fuel also. The check engine light is on.
Fuel consumption is 13.5 - 14.5 l/100km
What I have done so far is the following:
Initially LTFT was -15%
I replaced the MAF sensor with the original which I repaired (the electronics had come off the body so I plastic welded it back). No change in performance, still runs good, and LTFT moved to -10%
I don't want to start changing parts in the hope that somehow the problem will go away, so I would rather diagnose the fault.
Apparently the injectors were checked according to the mech.
For a rich code, the following come up as suggestions:
MAF sensor overreading - unlikely since both MAFS did the same thing and dirty MAF's tend to underread.
Fuel pressure too high - unlikely since the fuel filter has an integrated pressure regulator and it's an original part.
Dirty injectors - injectors apparently checked.
Faulty MAP sensor - I've checked the ambient but not the manifold one.
Faulty O2 sensor - O2 story below.
No hesitation on acceleration, great idle, the car runs really good.
I've plugged in my diagnostic tool and after a 20 minute trip the following are parameters are I've recorded.
Pre cat O2 sensor, voltage bouncing between 0.1 and 0.8 volts.
Post cat O2 sensor 0.85 volts - this seems a bit high to me?
Where to from here?
Ideally, what should a healthy post cat voltage reading be?
I'll A/B against my 2003 C200k and report back.
Suggestions welcome.
10-17-2016, 11:55 AM
#2
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How many miles do you have on the O2 sensors? The pre cat at one is the one that determines how much fuel needs to go into the mixture.
Hi
So I have brought this car back from the dead and had a blown head gasket repaired. It's got new pistons, piston rings, big end bearings, head gasket and aftermarket MAF sensor.
The mechanic who did the job for me returned the car. It's running great, plenty of power, but uses plenty of fuel also. The check engine light is on.
Fuel consumption is 13.5 - 14.5 l/100km
What I have done so far is the following:
Initially LTFT was -15%
I replaced the MAF sensor with the original which I repaired (the electronics had come off the body so I plastic welded it back). No change in performance, still runs good, and LTFT moved to -10%
I don't want to start changing parts in the hope that somehow the problem will go away, so I would rather diagnose the fault.
Apparently the injectors were checked according to the mech.
For a rich code, the following come up as suggestions:
MAF sensor overreading - unlikely since both MAFS did the same thing and dirty MAF's tend to underread.
Fuel pressure too high - unlikely since the fuel filter has an integrated pressure regulator and it's an original part.
Dirty injectors - injectors apparently checked.
Faulty MAP sensor - I've checked the ambient but not the manifold one.
Faulty O2 sensor - O2 story below.
No hesitation on acceleration, great idle, the car runs really good.
I've plugged in my diagnostic tool and after a 20 minute trip the following are parameters are I've recorded.
Pre cat O2 sensor, voltage bouncing between 0.1 and 0.8 volts.
Post cat O2 sensor 0.85 volts - this seems a bit high to me?
Where to from here?
Ideally, what should a healthy post cat voltage reading be?
I'll A/B against my 2003 C200k and report back.
Suggestions welcome.
So I have brought this car back from the dead and had a blown head gasket repaired. It's got new pistons, piston rings, big end bearings, head gasket and aftermarket MAF sensor.
The mechanic who did the job for me returned the car. It's running great, plenty of power, but uses plenty of fuel also. The check engine light is on.
Fuel consumption is 13.5 - 14.5 l/100km
What I have done so far is the following:
Initially LTFT was -15%
I replaced the MAF sensor with the original which I repaired (the electronics had come off the body so I plastic welded it back). No change in performance, still runs good, and LTFT moved to -10%
I don't want to start changing parts in the hope that somehow the problem will go away, so I would rather diagnose the fault.
Apparently the injectors were checked according to the mech.
For a rich code, the following come up as suggestions:
MAF sensor overreading - unlikely since both MAFS did the same thing and dirty MAF's tend to underread.
Fuel pressure too high - unlikely since the fuel filter has an integrated pressure regulator and it's an original part.
Dirty injectors - injectors apparently checked.
Faulty MAP sensor - I've checked the ambient but not the manifold one.
Faulty O2 sensor - O2 story below.
No hesitation on acceleration, great idle, the car runs really good.
I've plugged in my diagnostic tool and after a 20 minute trip the following are parameters are I've recorded.
Pre cat O2 sensor, voltage bouncing between 0.1 and 0.8 volts.
Post cat O2 sensor 0.85 volts - this seems a bit high to me?
Where to from here?
Ideally, what should a healthy post cat voltage reading be?
I'll A/B against my 2003 C200k and report back.
Suggestions welcome.
10-17-2016, 02:29 PM
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Incidentally I plugged my diagnostic scan tool into my 2003 C200K with the M271 engine, the one with bicycle parts for a cam chain. Got totally different O2 readings, with pre cat at 1.5 volts and post at about 0.6
My question is, surely the post cat sensors should give an overall indication of the richness / leanness of the combustion? What triggered the code?
What I did notice is that the C200 has almost half the MAF readings at idle, at 3.5 g/s as opposed to 6 g/s for the C230.
Apart from the obvious fuel trim issues that long term fuel trim at -12.5% is a problem , I don't have healthy ball park numbers to compare mine against to know where to look for a culprit. And obviously the M271 engine is a completely different design, almost nothing in common between that and the M111 on the C230 Sport coupe.
10-17-2016, 10:30 PM
#4
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Did you clear the codes after you put the OEM MAF back on?
Fwiw, the MB Service Manual on DVD and their WIS software are semi-garbage! No where, did I find anything about the DTCs, how they are set, the conditions that set them, etc.
WTF? - GARBAGE!
So, I checked my GM shop manual. For a GM, the DTC "basically" looks at the long-term fuel trim under the correct conditions.
For the GM vehicle I looked at, iirc, that rich P0172 DTC was set at -15%.
You should have/get a good scanner that has a good update rate, and can do graphs. The "Torque Pro (OBD 2 & Car)" app on Android is a good choice.
https://play.google.com/store/apps/d...g.prowl.torque
Here is an old screen shot taken with one of the ~second gen android tablets:
At idle, you'll see the short-term trim values creep up, and the O2 values follow.
When the mixture gets too lean, then short-term trim values creep down, and the O2 values follow.
When the mixture gets too rich, then short-term trim values creep up, and the O2 values follow.
When the mixture gets too lean, then short-term trim values creep down, and the O2 values follow.
And just keep repeating.
You may need to show just the trim and the O2 sensor, to see the displays fast enough.
But, if you see the O2 sensor values go up and down and up and down..., then the above is happening.
Btw, some okay web references:
http://www.troublecodes.net/pcodes/p0172/
http://www.troublecodes.net/pcodes/p0171/
http://www.troublecodes.net/pcodes/p0170/
http://www.troublecodes.net/pcodes/p0173/
Good Luck.
Fwiw, the MB Service Manual on DVD and their WIS software are semi-garbage! No where, did I find anything about the DTCs, how they are set, the conditions that set them, etc.
WTF? - GARBAGE!
So, I checked my GM shop manual. For a GM, the DTC "basically" looks at the long-term fuel trim under the correct conditions.
For the GM vehicle I looked at, iirc, that rich P0172 DTC was set at -15%.
You should have/get a good scanner that has a good update rate, and can do graphs. The "Torque Pro (OBD 2 & Car)" app on Android is a good choice.
https://play.google.com/store/apps/d...g.prowl.torque
Here is an old screen shot taken with one of the ~second gen android tablets:
At idle, you'll see the short-term trim values creep up, and the O2 values follow.
When the mixture gets too lean, then short-term trim values creep down, and the O2 values follow.
When the mixture gets too rich, then short-term trim values creep up, and the O2 values follow.
When the mixture gets too lean, then short-term trim values creep down, and the O2 values follow.
And just keep repeating.
You may need to show just the trim and the O2 sensor, to see the displays fast enough.
But, if you see the O2 sensor values go up and down and up and down..., then the above is happening.
Btw, some okay web references:
http://www.troublecodes.net/pcodes/p0172/
http://www.troublecodes.net/pcodes/p0171/
http://www.troublecodes.net/pcodes/p0170/
http://www.troublecodes.net/pcodes/p0173/
Good Luck.
Last edited by RedGray; 10-17-2016 at 11:14 PM.
10-18-2016, 03:45 AM
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Did you clear the codes after you put the OEM MAF back on?
Here is an old screen shot taken with one of the ~second gen android tablets:
At idle, you'll see the short-term trim values creep up, and the O2 values follow.
When the mixture gets too lean, then short-term trim values creep down, and the O2 values follow.
When the mixture gets too rich, then short-term trim values creep up, and the O2 values follow.
When the mixture gets too lean, then short-term trim values creep down, and the O2 values follow.
And just keep repeating.
You may need to show just the trim and the O2 sensor, to see the displays fast enough.
But, if you see the O2 sensor values go up and down and up and down..., then the above is happening.
Here is an old screen shot taken with one of the ~second gen android tablets:
At idle, you'll see the short-term trim values creep up, and the O2 values follow.
When the mixture gets too lean, then short-term trim values creep down, and the O2 values follow.
When the mixture gets too rich, then short-term trim values creep up, and the O2 values follow.
When the mixture gets too lean, then short-term trim values creep down, and the O2 values follow.
And just keep repeating.
You may need to show just the trim and the O2 sensor, to see the displays fast enough.
But, if you see the O2 sensor values go up and down and up and down..., then the above is happening.
To answer the cost question: I did clear the fault codes after fitting the OEM MAF.
I am beginning to suspect that it IS either the MAF or fuel pressure too high, because if the O2 sensors are faulty they would be telling the injectors to back off and that would create a lean mixture which would make the car stutter, hesitate and idle rough and it is doing none of those things.
The short term fuel trim and the O2 voltages are fluctuating as you describe.
I've attached pics of the obd scanner I have showing the data stream at idle with a warm engine and the graphs. From the min and max, you can see the B1S1 pre cat sensor going up and down aD well as the shot term fuel trim. The post cat is steady at 0.8V
It would be great to benchmark these numbers against a healthy '02 C230k..
Last edited by AK65; 10-18-2016 at 05:57 AM.
10-18-2016, 06:03 AM
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Just a quick update - it is unlikely the MAF sensor that came with the car is OEM - the OEM is a Siemens part with 5WK9613Z or A1110940148 stamped on it. This MAF has no markings whatsoever.
Last edited by AK65; 10-18-2016 at 07:59 AM. Reason: Correction
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10-18-2016, 02:20 PM
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in South Africa... I haven't tried unplugging the MAF cause I figured I would get a bunch of other codes without really knowing apart from better gas mileage if the MAF was the problem. I did notice on my trip back from the office today that the temperature quickly got to 70 Celsius and hardly got over 75 Celsius, which is on the cool side I think. Isn't the proper operating temperature around 90? Either the thermostat is not getting the engine up to temperature or the temperature sensor is faulty. Maybe that has something to do with it?
10-18-2016, 05:38 PM
#9
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I was battling a P0171 too lean code forever.
I finally got the codes read with an SDS, and it said something about a short in the MAF.
And when read with SDS it was it was too rich! P0172.
So, replaced the MAF with a Bremi, problems solved.
Also found a couple bad hoses along the way, replaced.
I finally got the codes read with an SDS, and it said something about a short in the MAF.
And when read with SDS it was it was too rich! P0172.
So, replaced the MAF with a Bremi, problems solved.
Also found a couple bad hoses along the way, replaced.
10-18-2016, 08:41 PM
#10
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Also, the issue is that the trim levels are bad. Unplugging the MAF won't prove anything, other than that MB has a preference for people to have their car towed asap when an error happens.
10-18-2016, 08:56 PM
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But, neither your car, nor my car, has that Space Alien :-O technology.
So, coming back to the real world, ALL "replaceable MAF units" require factory calibration. Also, there are tight tolerances in the electronics, materials, etc.
In other words, the non-Manufacture MAFs may or may not work!
Just because one person, or a few people, got "lucky" with some POS aftermarket MAF, that does not mean that the MAF isn't garbage! In fact, those POS MAFs are likely quickly calibrated to be sorta/kinda close at idle - so as not to cause an DTC/error-code. But, over temperature, humidity, and air flow, those POS aftermarket MAFs often show that they are a POS garbage part that doesn't even come close to factory OEM.
So, if someone want power, or gas mileage, or throttle response, or for their cats to last a long time, then a they should use only a factory OEM MAF.
Note, for GM/Ford, ProM has a line of MAFs that are good. But, again, in real life, it's "suggested/required" that the user puts the ProM flow numbers, from the flow measurement and error sheet that is with all of the ProM MAFs, into their computer tune.
Also, fwiw, those flow number are also based on an assumed pre-MAF intake setup. Any change, and the readings that MAF sends will have a greater error.
Imho, get an OEM MAF, even if it's from a local junk yard. I don't know what the s&h, import taxes, exchange rates are where you are.
Last edited by RedGray; 10-18-2016 at 09:20 PM.
10-18-2016, 09:17 PM
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My 2005 C230K with the M271 engine stayed right around 70C to 75C for the short time that I drove it.
10-19-2016, 04:29 AM
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[QUOTE=RedGray;6945675]My 2005 C230K with the M271 engine stayed right around 70C to 75C for the short time that I drove it.[/]
So my numbers are OK?
Incidentally I've attached some microscope pictures of the pirate Chinese MAF that the mechanic fitted, and it is an absolute PoS. It's as rough as old rope. No wonder the ecu doesn't like it.
So my numbers are OK?
Incidentally I've attached some microscope pictures of the pirate Chinese MAF that the mechanic fitted, and it is an absolute PoS. It's as rough as old rope. No wonder the ecu doesn't like it.
10-19-2016, 08:12 AM
#14
MBWorld Fanatic!
Hmm, imho, MB has some of the most stupid idiotic foolish Limp Home mode modes that I'm aware of in an EFI car made after 1990.
Also, the issue is that the trim levels are bad. Unplugging the MAF won't prove anything, other than that MB has a preference for people to have their car towed asap when an error happens.
Also, the issue is that the trim levels are bad. Unplugging the MAF won't prove anything, other than that MB has a preference for people to have their car towed asap when an error happens.
Also while I agree that the manufacture MAF is the best option. It should also be noted that there is a difference between OEM and OE. I have bought some OEM parts that were not the same quality as the OE part. OEM = original equipment manufacture (does not have to pas MB testings/standards) and OE = original equipment.
Last edited by insame1; 10-19-2016 at 08:16 AM.
10-19-2016, 08:45 AM
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Not true. No reading from the MAF goes into a "limp" mode. If you unplug the MAF and the car runs slightly better chances are you have a bad MAF.
Also while I agree that the manufacture MAF is the best option. It should also be noted that there is a difference between OEM and OE. I have bought some OEM parts that were not the same quality as the OE part. OEM = original equipment manufacture (does not have to pas MB testings/standards) and OE = original equipment.
Also while I agree that the manufacture MAF is the best option. It should also be noted that there is a difference between OEM and OE. I have bought some OEM parts that were not the same quality as the OE part. OEM = original equipment manufacture (does not have to pas MB testings/standards) and OE = original equipment.
I'll either try an original Mercedes part from a used parts yard or a new Bremi or Pierburg european manufacturer. This is the second Chinese one that looks like it was made in a back yard.
My problem about unplugging the MAF is I doubt the car will run better because it is running quite well. Idles great, no hesitation on acceleration and plenty of power. Just using a lot of fuel and the check engine light is on. On my way back, I'll unplug it and see if I get better fuel economy.
I'm just hoping it does not run rough... my old BMW E46 325i ran the same with or without the MAF...so here's hoping
10-19-2016, 10:42 AM
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Well it turns out the MAF I have on now IS the original Mercedes / Siemens part. I was just too blind to see the numbers on it. Getting old sucks! I hope to hell it is shot, because if it is not, I really don't know where to look next 
10-20-2016, 09:56 PM
#17
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Change the primary O2 sensor, then change the MAF.
It's unlikely a fuel injector, since you don't have a cylinder misfire error.
It's unlikely a vacuum or gasket leak, since the engine is not running too lean.
It's unlikely a fuel injector, since you don't have a cylinder misfire error.
It's unlikely a vacuum or gasket leak, since the engine is not running too lean.
10-21-2016, 07:03 PM
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Update: I strongly started to doubt either the O2 or MAF sensor, since the engine was running in closed loop, albeit with horrible amounts of trim, and changing the Chinese MAF back for the original made no difference, and there were no MAF related fault codes.
I started to suspect unmetered fuel was entering the system. The fault was set when Long Term Trim was at -12.5 and short term trim was -11.7 The fuel filter started to look to me to be a likely suspect, as there is a vacuum operated pressure control regulator / diaphragm built in. Judging by the state of maintenance of the car in general when I bought it, I figured it would not hurt to change the filter ANYWAY. Everything else in the car was in a shocking state of neglect.
In the process of changing it, I moved all the fuel lines to the new filter and when I removed the vacuum line from the old filter, fuel came gushing out of it, a LOT of fuel. It is supposed to only carry vacuum. So I am pretty convinced I've found the problem, although a thorough test will reveal if all is good. It was probably sucking fuel directly into the throttle body. It would seem that all of these fuel filters will fail in this manner, and many others might be in the same boat as me. Anyhow, I'll report back as to whether this fix worked.
I started to suspect unmetered fuel was entering the system. The fault was set when Long Term Trim was at -12.5 and short term trim was -11.7 The fuel filter started to look to me to be a likely suspect, as there is a vacuum operated pressure control regulator / diaphragm built in. Judging by the state of maintenance of the car in general when I bought it, I figured it would not hurt to change the filter ANYWAY. Everything else in the car was in a shocking state of neglect.
In the process of changing it, I moved all the fuel lines to the new filter and when I removed the vacuum line from the old filter, fuel came gushing out of it, a LOT of fuel. It is supposed to only carry vacuum. So I am pretty convinced I've found the problem, although a thorough test will reveal if all is good. It was probably sucking fuel directly into the throttle body. It would seem that all of these fuel filters will fail in this manner, and many others might be in the same boat as me. Anyhow, I'll report back as to whether this fix worked.
Last edited by AK65; 10-21-2016 at 07:17 PM.
10-21-2016, 08:38 PM
#19
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I started to suspect unmetered fuel was entering the system. The fault was set when Long Term Trim was at -12.5 and short term trim was -11.7 The fuel filter started to look to me to be a likely suspect, as there is a vacuum operated pressure control regulator / diaphragm built in. Judging by the state of maintenance of the car in general when I bought it, I figured it would not hurt to change the filter ANYWAY. Everything else in the car was in a shocking state of neglect.
In the process of changing it, I moved all the fuel lines to the new filter and when I removed the vacuum line from the old filter, fuel came gushing out of it, a LOT of fuel. It is supposed to only carry vacuum. So I am pretty convinced I've found the problem, although a thorough test will reveal if all is good. It was probably sucking fuel directly into the throttle body. It would seem that all of these fuel filters will fail in this manner, and many others might be in the same boat as me. Anyhow, I'll report back as to whether this fix worked.
In the process of changing it, I moved all the fuel lines to the new filter and when I removed the vacuum line from the old filter, fuel came gushing out of it, a LOT of fuel. It is supposed to only carry vacuum. So I am pretty convinced I've found the problem, although a thorough test will reveal if all is good. It was probably sucking fuel directly into the throttle body. It would seem that all of these fuel filters will fail in this manner, and many others might be in the same boat as me. Anyhow, I'll report back as to whether this fix worked.
Great catch on the fuel pressure regulator!
Gee, I guess it shouldn't surprise me. Since, imho, a good portion of the early 2000's C-class vehicle design seems similar to the GM 70's, 80's, 90's, 2000 philosophy of designing many parts to the minimum to barely last ~60K-90K miles.
Fwiw, GM's fuel pressure regulators are infamous for leaking and being purposely under designed (to save cost) for 20++ years.
When the fuel regulator leaks like that, then it's often harder to start the car up when soon after you shut it off. Such as a quick 2-5min stop at a store. That's because there's extra raw fuel inside the intake. So, it takes a few more cranks to clear out that extra raw fuel.
Fwiw, a clogged/bad fuel filter couldn't cause a rich condition.
Imho, you should replace the O2 sensor. After ~80K miles, all O2 sensors get slow (slower to respond) and start to read a little lean (~1-2%) - causing a more rich mixture - less gas mileage, but a little more performance.
If the engine was burning oil or antifreeze, then that O2 sensor is either garbage, or close to being garbage.
Also, as an FYI: The cat may be more clogged. That effects performance, max HP, and depending on driving habits - maybe gas mileage. So, depending on the purpose or desire of the car, replace the cat after the secondary O2 sensor indicates that the cat is no longer doing it's function, or replace it now.
Fwiw, for my 2005, with an M217 engine, I went with a Kleeman header and cat.
https://www.gmpperformance.com/index...ail&PID=318228
Note: The Kleeman header and cat may not be smog legal - depending on local smog laws.
Last edited by RedGray; 10-21-2016 at 08:44 PM.
10-22-2016, 09:46 AM
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Latest update. After eventually finding the mislaid key, I decided to let the fuel run out of the 'vacuum' line. After no sign of the fuel letting up, I started to suspect maybe it wasn't a vacuum line at all.
Turns out it's a equalisation line and goes back to the fuel tank and it is supposed to carry fuel. So much for that 'fix'. Turns out I've been barking up the wrong tree. The 'vacuum' line coming from the throttle body is something to do with the EVAP control system, and it's controlled by an ECU operated Purge valve. So my C230 has a new fuel filter but I'm no closer to solving my problem.
I did suspect something when RedGray, you mentioned that the engine would be hard to start after parking for a while, and I have no problem like that. The engine starts first swing and apart from the rich code and eye watering fuel consumption, the car runs great. That's with long term trim at -12.5%, which means the ECU is subtracting fuel and the car is still running great.
I don't suspect O2, because I think they would cause a false lean condition. Either the engine is over measuring the air (MAF overreading) or the fuel injectors are injecting too much fuel (maybe they are the wrong type?)
I'll replace the MAF with a European part and see what gives.
At least I wont' have to change the fuel filter LOL.
So back to the drawing board.
Turns out it's a equalisation line and goes back to the fuel tank and it is supposed to carry fuel. So much for that 'fix'. Turns out I've been barking up the wrong tree. The 'vacuum' line coming from the throttle body is something to do with the EVAP control system, and it's controlled by an ECU operated Purge valve. So my C230 has a new fuel filter but I'm no closer to solving my problem.
I did suspect something when RedGray, you mentioned that the engine would be hard to start after parking for a while, and I have no problem like that. The engine starts first swing and apart from the rich code and eye watering fuel consumption, the car runs great. That's with long term trim at -12.5%, which means the ECU is subtracting fuel and the car is still running great.
I don't suspect O2, because I think they would cause a false lean condition. Either the engine is over measuring the air (MAF overreading) or the fuel injectors are injecting too much fuel (maybe they are the wrong type?)
I'll replace the MAF with a European part and see what gives.
At least I wont' have to change the fuel filter LOL.
So back to the drawing board.
01-25-2020, 06:33 PM
#21
Did this ever get resolved?
Latest update. After eventually finding the mislaid key, I decided to let the fuel run out of the 'vacuum' line. After no sign of the fuel letting up, I started to suspect maybe it wasn't a vacuum line at all.
Turns out it's a equalisation line and goes back to the fuel tank and it is supposed to carry fuel. So much for that 'fix'. Turns out I've been barking up the wrong tree. The 'vacuum' line coming from the throttle body is something to do with the EVAP control system, and it's controlled by an ECU operated Purge valve. So my C230 has a new fuel filter but I'm no closer to solving my problem.
I did suspect something when RedGray, you mentioned that the engine would be hard to start after parking for a while, and I have no problem like that. The engine starts first swing and apart from the rich code and eye watering fuel consumption, the car runs great. That's with long term trim at -12.5%, which means the ECU is subtracting fuel and the car is still running great.
I don't suspect O2, because I think they would cause a false lean condition. Either the engine is over measuring the air (MAF overreading) or the fuel injectors are injecting too much fuel (maybe they are the wrong type?)
I'll replace the MAF with a European part and see what gives.
At least I wont' have to change the fuel filter LOL.
So back to the drawing board.
Turns out it's a equalisation line and goes back to the fuel tank and it is supposed to carry fuel. So much for that 'fix'. Turns out I've been barking up the wrong tree. The 'vacuum' line coming from the throttle body is something to do with the EVAP control system, and it's controlled by an ECU operated Purge valve. So my C230 has a new fuel filter but I'm no closer to solving my problem.
I did suspect something when RedGray, you mentioned that the engine would be hard to start after parking for a while, and I have no problem like that. The engine starts first swing and apart from the rich code and eye watering fuel consumption, the car runs great. That's with long term trim at -12.5%, which means the ECU is subtracting fuel and the car is still running great.
I don't suspect O2, because I think they would cause a false lean condition. Either the engine is over measuring the air (MAF overreading) or the fuel injectors are injecting too much fuel (maybe they are the wrong type?)
I'll replace the MAF with a European part and see what gives.
At least I wont' have to change the fuel filter LOL.
So back to the drawing board.
i have a 2005 that has the code. Exhibits rough idle, lag on acceleration, plus sounds like an exhaust leak.
02-13-2022, 06:53 AM
#22
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2003 s500
c230, 2.3l, being a BEAST
I have a 2002 c230 kompressor, exact same symptoms as above, and am also looking for resolution, have done everything mentioned previously in this thread except O2 sensor. i cleaned the MAF sensor, no noticeable difference. Thinking one of the 2 needs replaceed.
