I have a 1997 C230 with 74k miles. It is misfiring on various cylinders according to "car chip" computer reader. This has been going on for about nine months. At first it was once every 3 months, now every week. At first it was only one cylinder, now I am getting random readings. Anyone have any answers, could it be the engine wiring harness(independent service person mentioned this).

 

ok, I have the same problem with my c230, and I really hope we can work out this together, according to the information i was able to get at alldata, the cause of this could be an injector, that does not close properly or due to engine wear. I would try getting a new set of injectors my self, but honestly, i do not have the means at the moment, so if You or somebody comes forward with some help, i t will be greatly appreciated.</P><edited><editID>harryfrank</editID><editDate>38072.5598032407</editDate></edited>

 

I went back and read what I had written, did not make much sense, so here I go again trying to be more specific.</P>


I have a c230 1997, and have the engine light come on a few times.</P>


According to the scan tool, the computer decided there was a misfire in cylinder one, so I went and did the cheapest fixed, which was to replace cables and sparkplugs. Since the light was still on, I went and unplug the battery for 5 minutes and put it back on. </P>


The problem got fixed for a while, I even went all the way to mexico in it without seeing the light come on again. that is like 1400 miles from where I live. Any way, while down there the light went on and I had the car scanned there, the car had a low gas sensor problem, another problem not related to the misfire,</P>


but it did not have the misfire along with it, and that is what counts. I drove another 1400 miles back to the US, and a day later from being at home...Yeap you guessed the light came on, and it was the missfire deal again, I have reset the codes by unpluggin the battery and keeps coming back with the same error. </P>


According to alldata, who provides technical info on all vehicles, this meant that my engine was worn out (from that long trip maybe?.. I do not think so) or I had a bad injector. I have driven my car for a nother 4 months with the light on and I have reset it a few times more with no luck, it comes on a little bit later.</P>


I know is not the engine, because it does not burn oil and works fine. So my next step will be to take the injectors and clean them my self!</P>


Again, if anybody out there had this experience...please advise.</P><edited><editID>harryfrank</editID><editDate>38072.5596527778</editDate></edited>

 

I have a 95 C280 which I bought with theengine light on<IMG src=smileys/smiley5.gif border="0">. Hoping it was something simple like a bad oxygen sensor or something, I drove it home from Texas and it was misfiring and it would revv up to about 4000 RPM before shifting. I took it home and changed the plugs and fuel filter and nothing, I took it to my benz mechanic and they hooked it up and got a reading that the fuel mixture was too lean, but they said I needed a new wiring harness, so $1300.00 later the car is doing great, no misfiring,hesitation, rough idle. All cured and for such a modest price too. <IMG src=smileys/smiley2.gif border="0"> I paid way too little for this car and I now know why but overall I'm very pleased. This is my third Mercedes and I won't drive anything else.

 

Yesterday after work I finally decided to clean the injectors, ( I did not mention before that before going to Mexico I had put some injector cleaning thing in my fuel tank, so that could have helped...), I took 2 screws out , took all 4 injectors out, (this would cause some fuel spill, and of course do this with the battery unplugged, for safety). I noticed there was a little bit of dust built around the bottom o rings, so took them off clean them, and decided to flip it over, since the bottom was kind of burned from contact with the engine. then I connected a small hose to the injector, (thats all i had on site), and filled it up with a mixture of thinner and gasoline, (yeah, yeah, thinner is too strong but i took my chances), after this i applied 12 volts on and off to it while blowing into the hose <IMG src=smileys/smiley8.gif border="0">, after a while you could see a nice stream coming out of the injector, put them back together and then put a little more of this mixture inside the fuel rail before putting the last injector back on . I attached the rail back to the engine, and then try to start it, I knew it would be hard, specially with the rail half empty and the mixture i put in, so i had to crank the engine 6 or 7 times before it kept idle by itself, then once it did, I went back and turn the engine off and unplugged the battery to have the engine light go off. After 5 minutes i plugged it back on and went for a test drive, the car performed great, I mean real smooth, and the engine light that would normally go on within 10 minutes did not, I drove it to work this morning and after a smooth ride the light has not come back on, let's hope that fixes it, but I will keep you guys informed.....</P><edited><editID>harryfrank</editID><editDate>38072.5599537037</editDate></edited>

 

ok, I'm back this time the light took 2 days to come back on!!! good , we are getting there... however the code in the computer shows po170, which is a problem detected on one of the fuel banks, from reading here and there I discovered I could swap ingnition coils and see if the problems changes to another bank, that way all i would have to do would be to buy a new coil, let's hope it works.</P>


help!!!!!!!!!<IMG src=smileys/smiley19.gif border="0"></P><edited><editID>harryfrank</editID><editDate>38072.5602546296</editDate></edited>

 

<IMG src=smileys/smiley4.gif border="0"> Guess what guys....I did not switch the bobbins but I got it fixed!!!!!!!!!</P>


After going to a few reviews and forums, I noticed that one of the main complaints in some mercedes was the MAF (MASS AIR FLOW SENSOR), so I made the BIG and then not so big mistake of trying to clean it. So I took it apart and put some cleaner in it..... BIG mistake! I actually finished ruining it. The car would stall unless I had my pedal on the gas!!!!. I relized it had to be the "cleaning" I had performed, so after this I drove it Inoticed 30% improvement on a transmission issue I had!! why?..the MAF senses the amount of air that goes into the engine to calculate load and how much gas goes into the injectors! but also and most important it tells the computer when to shift!!!, I had bought the car like this and have always considered the car to lack some power (thinking...well, I had a v8 this is only a 4, I guess is ok for a 4 cilynder ). NO WONDER!...the issue was that my transmission would not shift gears soon enough, and I always thought that it was deterioreting little by little.because It was not that bad when I first bought it. Then it was giving me all those p017x errors that were supposed to be related to injectors and gas. that is why I decided that I was to find the problem around the injectors or spark plugs.</P>


Anyway I had to drive with both feet on the pedals for 2 days to overcome my pride andbuythe sensor paying overnight shipping too!! <IMG src=smileys/smiley19.gif border="0"></P>


Yeah, I was going torisk345 dollars to see if the air mass flow sensor was my problem... and guess what!!!!I did not only gained that 30% increase in power, but gained smothness at idle and great performance!!!! The engine light is gone and I'm sure I will not be seeing it anytime soon!!!</P>


BELIEVE ME, that sensor makes the difference between a mercedes and A MERCEDES!!! if You know what I mean...Mercedes rock!!!! <IMG src=smileys/smiley10.gif border="0"><IMG src=smileys/smiley10.gif border="0"><IMG src=smileys/smiley10.gif border="0"><IMG src=smileys/smiley10.gif border="0"><IMG src=smileys/smiley10.gif border="0"></P><edited><editID>harryfrank</editID><editDate>38077.3349305556</editDate></edited>

 

first off when i read this, if a enigine light comes on u need to see a dealer and have a system scanner on your car and dont clean everything with brake cleaner or anything else, youre asking for trouble.</P>


ya if theres a misfire its either lean or rich, so ya MAF might do it. these are like 50k dollarcars and youre "guessing" and cleaning everything is real risky. next time just fork out money and see a dealer, risking a bigger problem is not worth it on a nice car</P>

 

I just went through this engine misfire with my 1998 c230. I changed spark plugs when I encountered a bad hesitation and misifre in November of 2005. It didn't fix the problem. I have been struggling with this problem since then and finally broke down and took the car to a dealership where they ran there diagnostics on it. There was a problem with the air/fuel metering controlled by the computer which they reset but they said that because I had installed platinum plugs there was no guarantee the problem would go away. The CEL light remained on after I picked up the car but I immediately picked up some non-platinum plugs, changed them, and the car was unbelieveably fixed and runs great. I have never heard of such a thing. I believe that the combination of being platinum and the fact that the plug gap on the platinum plugs was very wide caused a high resistance and misfire the dealer told me was the part of the cause.

Problem solved. Under $7 for the plugs but the diag and other adjustments cost me $200

 

Not sure where to post this...but this thread seems most relavant. I hope someone could use this info, since I was able to fix my 1996 c280 (113k miles) from this forum (great forum for Mercedes owner who are trying to be DIY mechanics, and trying to save some money). Hope someone else could benefit. Thanks!

Long story short, I had hesitation on hard acceleration or uphill accel, lost of power or no power thereafter. Very rough idle during stop (sometimes just "slightly" rough idle during stop). Once in this mode, only stop engine and restart engine would make it go away. Check engine light was on prob for 6 months, but had no symtoms (I had a baby, so no time for anything!). Finally had time, read A LOT on this forum.

First thing was change the 6 spark plugs. Got Kragen's "recomended" platimum plugs (two prongs) $4.95 ea.. Problem seems to go away, but, I think, was only masked by "seemingly" stronger engine performance. By the way, this is the first time changing these old plugs!

2nd thing was to check and change plug wires (a set of 3 ~$130). Didnt see any cracks, or otherwise bad wires, but installed new ones anyways. No change. Still same problem.

3rd was to change Mass Air Flow (MAF) sensor. Many posts had this as the solution. Cheapest new was $200 on ebay ($500 at dealer, just for the part). Some used ones can be had for ~$140, but didnt want to chance it. At first, problem seems to go away...no more hesitation/rough idle for 2 days, but still had backfires once a while during hard acceleration or climbing hills, as well as slight power hesitation. Then problem came back. So now I reset the computer by trying Sleepwalker's suggestions with the battery terminals. Noted the check engine light for the next occurance of the problem. Once the light came back on, this time, I bought a OBDII reader ($75) and saw #5 cylinder misfire/ multiple cylinder misfire codes.

THEN, I saw this post from tomk.

Went back and REGAPPed the OLD plugs to 1mm (all 6 old plugs were at ~1.5 to ~2mm) and replaced them. BAM! NO MORE PROBLEM. Never ever heard of this before, until I found tomk's posts! Thanks! This forum is great!

Summary: probably combination of Mass Air Filter problem and over-gapped spark plugs. Wish I had the code reader before reseting the computer, just to know.


PS. Just in case someone who knows reads this: during one of my plug replacement session, I broke these yellow tubes that were running along next to the ignition wires (very brittle - so be careful!) I managed to glue them solidly together, but in case these become a problem later, does anyone know what they are and how to get them (besides the dealer, I mean). Thanks.