[Behind Blue Eyes]

Hello,

I am getting back 2 error codes on my99 C230 K.

P0304 - CYL. 4 Misfire
And,
P0170 - Fuel Trim Malfunction, Bank 1

When it starts to miss all I have to do is stop, turn off the key, wait about a few seconds, then start it up and it runs good again. It seems to get this malfunction if i accellerate heavily, or on the freeway. If I drive it easy it is not a pervelant.

From what I can see it seems it might need an injector on #4 CYL. Does anyone have a fuel injector for sale? The part number of the injector is 000 078 81 23 . If someone has one or can tell me what might be going wrong I would appreciate it.

If anyone has an injector I would really apprecite it. ALSO: could it be the fuel filter being dirty/plugged?

Thanks for the anticipated help.

Geo

 

[bmeister]

Before you go buying a new injector ohm test them and compare readings. I had the Po170 with a #3 malfunction and if was the MAF. Has this ever been cleaned or changed?
I am sure the Maf wonder boy is on his way. It may be a case of cause and effect.
You should also pull that plug and check its condition as well. B

 

[liquidusculade]

here is what i recommend. erase the codes and recreate the condition, then get the codes read again. im not saying they are wrong, but i think the fuel trim one, might be an old code.

also, when was the last time you replaced your spark plugs. if it was recent, you can take #4 out, inspect it, and see if its fine. if it looks ok, then its most likely the wire.

the fuel trim is due to the fuel/air mixture being off. there could be many things that cause this.

also check your vacuum lines for leaks, check the vacuum line at the fuel pressure regulator.

 

[Behind Blue Eyes]

OK, I am gonna check the plugs. I dont know how to test the injectors with a meter.

Can you tell me where the MAF sensor is so I can take it out and fix cnean it.
How do you clean it?

 

[liquidusculade]

maf's are very sensitive. some people argue that cleaning them wont do anything. however, crc makes a maf cleaner spray. you just spray it on, and it dries itself, there is no need to actually touch the maf. you shouldnt touch the maf. the maf is located in the air intake after the air filter. it will be the first electrical plug you see coming off the air duct after the air filter.

there are some clips that allow it to be removed from the air duct. spray the sensor down with some cleaner and hopefully that helps. do you know where the fuel pressure regulator is to check the vacuum line?

 

[Check Codes]

Hey Geo.

If you're going to clean the MAF, clean it properly. Don't just spray down inside the tube, the odds of you cleaning what you need to are like 3% if that. Rather remove the assembly, then remove the insert from it, you can follow the DIY I did in the W210 forum, quite similar assembly and the insert is virtually identical. The pic below is of the one for your car. I'm one of those that says cleaning an MB MAF is usually a waste of time, but it doesn't hurt to try so long as it's done correctly.

I'd be surprised if a fuel filter is the issue as that would cause other misfires. But if it's old and needs to be changed of course do that.

You can also swap injectors and see if the miss moves, same with ignition wires and coils. Obviously don't move all of them at once!!

Take care and enjoy the ride,
Greg

 

[bmeister]

Maf-a-rama

OK, I am gonna check the plugs. I dont know how to test the injectors with a meter.

Can you tell me where the MAF sensor is so I can take it out and fix cnean it.
How do you clean it?

Get a meter and set it on the ohm setting.
Here is some instructions on the Maf. B

 

[Behind Blue Eyes]

Thanks guys.

Liquid, no i dont know where that fuel line is. If you tell me i will check it.

I read everything you all said. as far as swaping the injector that sounds like a good idea. Just to see if the error follows where the new injector is. Does anyone have a PDF on how to change a fuel injector?

 

[liquidusculade]

i think swapping a plug or wire (depending on which wire it is) would be easier than swapping an injector. also, thats why i recommended clearing the codes and recreating the problem. im interested in seeing if the misfire stays on cylinder 4.

ok, i just stole this picture and i circled the fuel pressure regulator in red. there should be a vacuum line that connects to the top of it from your intake manifold.

 

[Check Codes]

i think swapping a plug or wire (depending on which wire it is) would be easier than swapping an injector.

I agree, Liquid, but at least on the MB's I've toyed with, there isn't any room to swap wires. Those Germans don't give you ANY extra leeway.

OP, I think I'd do the injector last. Coils and ignition wires and plugs are lots easier to move, if you swap all those, clean the MAF, clear the codes and it still comes back to #4, then you know -- almost without a doubt -- that it's the fuel injector.

Take care and enjoy the ride,
Greg

 

[liquidusculade]

i agree that it is a little tight, but its possible, at least on my non kompressor model to reach down in and pull the plug wires off the coil pack. ive never had to change a coil pack so im not sure how difficult that is, but im assuming its not the coil since its only one cylinder and not two that are misfiring.

 

[Behind Blue Eyes]

I got it. First thing I am gonna do is check the plug's and wires.

I dont have a manual, and I know i need to buy one, but is it a big deal to take out and change or move an injector? I will try the spark plug end of it, but if that doesnt work I would like to also try switching the injector like someone suggested.

If anyone has a PDF on how to change an injector I would appreciate it.

BUT... the funny part about the misfire is it will start up, and when you stop at a traffic light... so I shut the ignition off and then when i restart the car its back to normal.

Would that suggest there might be a problem with the ME?

Geo

 

[xvvvz]

Just in case there is confusion, the MAF is NOT located under the yellow arrow on a c230k. It is down at the end of the long black tube shown on the right side of the engine/picture. It is down at the bottom by the radiator and one end attaches to the intercooler (where the clips are located).

 

[Behind Blue Eyes]

OK. I changed the spark plugs. Got Iridium plugs AND i took out and cleaned the MAF with the CRC MAF cleaner. Bad connection on the wires and my supercharger would NOT work till I really cleaned the wire connection to the MAF. Seems to run good. BTU... the new codes:
P0170 - Fuel Trim Bank One (didnt go away)
P1000 -
P0110 -

Sound like the MAF? Car runs good, but I think it can do much better. What does it sound like my next move should be on these codes??

Geo

 

[Behind Blue Eyes]

OH sorry . Mistake on the new codes.

P0170
P0100 (NOT P1000)
P0110

Sorry bout the typo. What do these codes mean?

 

[liquidusculade]

well here is a link that shows what your codes mean:
http://www.diagnosticsolutions.ie/iopen24/pub///MB DTC.pdf

you now have maf and air temp sensor codes. not too sure why your getting them, but it could be the maf.

i would recommend recleaning the maf, and also clean the air temperature sensor, with the same cleaner, which is another connector that comes off the intake tube before the throttle body.

then clear the codes and see if they come back. if they do come back, get them read and see which ones come up. your problem unfortunately is most likely the maf since they are common problems, however they can be expensive. autohaus i think has the best prices for the whole maf, and germanstar sells the maf insert i think which will be the cheapest route. you could also try replacing the air temperature sensor first, since that is the cheapest, but ive never heard of one of them being faulty.

 

[Behind Blue Eyes]

Liquid,,

I was reading another thread that says that its an improvement to take out the screen inside the MAF. They were also talking about a resistor or something simular to bypass the MAF all together.

guess i gotta go looking for an MAF for my 99 c230 K. Anyone got a good one for sale?

Geo

 

[liquidusculade]

Liquid,,

I was reading another thread that says that its an improvement to take out the screen inside the MAF. They were also talking about a resistor or something simular to bypass the MAF all together.

guess i gotta go looking for an MAF for my 99 c230 K. Anyone got a good one for sale?

Geo

i wouldnt recommend modding your maf. its there for a reason, and if you try to bypass it you can cause way more damage than the maf is worth to replace it in the first place. its also important that you get a quality maf. the Bosch units are quality however alot of people sell fake boschs on ebay. i believe autohaus is where you will find the best price on a known good product as i said before. here is the link to your maf:

Your Parts Search Returned 1 Part(s)

also, as i said before germanstar i believe sells just the insert into the maf housing, for less than it costs to get the maf and the housing all together like what is sold at autohaus, however if your not handy with some simple tools, then just buy the whole unit.

her is the link to the maf insert from germanstar.
http://germanstar.net/MAF.htm

 

[doin12volt]

I had the p0170... car ran great - I changed about everything I could think of and STILL had the p0170 code --- UNTIL i put in a new BOSCH MAF. the other one i have still works great but it triggers the p0170 code.

 

[cjshade]

MAF Blues

MAF Wonder Boy here to say GOOD JOB to all you guys!:thumbsup:

I was away for a few days and missed the beginning of this Thread! I'm not suprised to see the outcome though...

Good Luck!:thumbsup:

C as in 220