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Help with engine misfire codes

3K views 15 replies 5 participants last post by  johnny63ml320 
#1 ·
Hello Guys,

My car is running very rough and shakes alot and when driving the car accelerates really slow and has no power that I'm scared to drive it now until i get it fixed. I hope you guys can help me figure out the problems.

Below is my journal:

Here are the codes I got by running a scan.

P0173 Fuel Trim Malfunction (Bank 2) )
P0170 Fuel Trim Malfunction (Bank 1) )
P0221 Throttle/Petal Position Sensor/Switch B Circuit Range/Performance Problem
P0305 Cylinder 5 Misfire Detected
P0301 Cylinder 1 Misfire Detected
P0300 Random/Multiple Cylinder Misfire Detected

------------------------------------------

After installing the Mass Air Flow Sensor today I only have these codes.

P0305 Cylinder 5 Misfire Detected
P0301 Cylinder 1 Misfire Detected
P0300 Random/Multiple Cylinder Misfire Detected
P0305 Cylinder 5 Misfire Detected
P0301 Cylinder 1 Misfire Detected
P0300 Random/Multiple Cylinder Misfire Detected
They read out repeating each other once.

I guess the Mass Air Flow Sensor fixed the P0173 P0170 P0221 but still have the other three codes to worry about.

Background Info:

2001 Mercedes ML 320 , 65,000 miles
Recent Service “A” about a year ago.
All Coil replace were around 30,000 miles in ’03.
Last fuel filter done at 26k miles in June 2002 which includes the scedule B service.
Just installed new Mass Air Flow Sensor.
Car get machine car wash every two weeks.
Let me know if u need more background info.

Thanks in advance.
Johnny.
 
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#2 ·
Did you remove the codes after MAF replacement?
Some of them will clear them-self after few restarts (I counted 7) some might be permanent, till removed.
Clear all the codes and take it for long drive.
Than recheck.
My son had very similar situation. The truck had 10 codes stored. Replacing MAF and clearing the codes solved the situation.

BTW welcome to the forum.
 
#4 ·
catalytic converters recall?

Hello Joe,

I dont know what to check for the catalytic converters? How to test for malfunctions? I heard there is a recall for them on the boards and searched on line and found that the 99-2001 cars have under the hood catalyst cans may develop cracks along the weld seams btw the inlet funnel and the can of the body. ( see this link http://www.epa.gov/oms/cert/recall/2005recallreport6.pdf ). Does that mean the catalystic convert it self? Is that the recall? if not, what the warranty on the catalystic convert for a 2001 ml with 65k miles?? I'm in Califonia by the way.

Thanks.
JOHNNY.
 
#6 ·
replaced all plugs

Ok, I replaced all the 12 plugs today and the car is running about 75% better.
Now all i have is one code remaining after i cleared the code after installing the plugs. (P0305 Cylinder 5 Misfire Detected). I will try to replace the coil and wire for that cylinder and see what happens tomorrow? Btw how do you know when to replace your O2 sensors?

-johnny
 
#7 ·
johnny63ml320 said:
Ok, I replaced all the 12 plugs today and the car is running about 75% better.
Now all i have is one code remaining after i cleared the code after installing the plugs. (P0305 Cylinder 5 Misfire Detected). I will try to replace the coil and wire for that cylinder and see what happens tomorrow? Btw how do you know when to replace your O2 sensors?

-johnny
Err, before you went to all that trouble you should get the codes reset by the dealer. My mechanic who happens to be very good friends with the MB dealer mechanic said most of these codes are set by a faulty MAF. AND the codes must be reset by the dealer scanner after it is replaced. Dont know how true it is, but I just got mine back and its running like a dream so far. Will be keeping tabls on it with the occassional kickdown here and there. I usually drive very gently and keep the l/100k's figure down as much as possible. I cant afford to maintain my merc and put petrol in it.
 
#9 ·
Hey guys, the check engine light has nothing to do with the running performance of the vehicle...............only the malfunctioned component does. It is not necessary to have a dealer reset the codes. If you don't have your own scanner to do it, simply disconnecting the negative battery cable will do the same exact thing and the existing code or codes will then be stored in history faults. If the original problem was repaired correctly, you could drive forever with the check engine light on, with no change in performance , the only drawback would be that you will not know if you have a new problem developing.
 
#10 ·
43sqd said:
If the original problem was repaired correctly, you could drive forever with the check engine light on,.
I had the light on only couple of times, but it clears itself.
After replacing faulty MAF sensor I kept on turning the engine on and off. Took 7 times to clear the light off.
Now on E300D I have some glitch on gas pedal switch, that triggers the light and error. Didn't count it yet, but the impression is that it took about 20 restarts to clear the light off. Than the error comes back without specified time, so it might relight in the mean time.
Maybe qualified technician would confirm that, but from what I learned, the miscellaneous codes needs several occurrences to trigger the CE light and few good restarts to go off.
Meaning the light is not necessary coming, or going at the same time the errors happens, or clear.
 
#11 ·
Kajtek1 said:
As I sad in my response above, the $80 reader cleared all those codes with no problem.
I believe O2 bad sensor will trigger its own code, but haven't experienced that yet (knock on the wood).
So Katjek1, Do the aftermarket code readers available clear codes as well. I want to get one, for all I know, my MAF may have been ok after I cleaned it. But I will never know now since I could not clear the codes. Where can I buy one from. I am heading to the US next week for a week. Travelling from San Fran to Vegas to Seattle and ending up in Portland OR. I am sure they are much cheaper in the US than here in Australia
 
#13 ·
I lived in the US for 7 years. 15 months in Boston, and the rest in Portland OR. Traveled from East to West about 3 times. I have moved back to Australia now but I made a lot of friends over there. I am spending about a week there with my fiancee (reason why I moved back) She has never been here so I thought I try to jam as much as i can show her in a week. We are flying inot San Fran, staying in Union Square for a night. Show her Fisherman's wharf, take a cable car. Go up to the Television towers so she can see the whole city and bay. I love san Francisco. If there was a place I would live, that would be my first choice. We are then renting a car and driving to Reno through lake Tahoe. Catching a plane to Vegas for 2 days, then a plane to Seattle and drive to portland. I think for a week I am getting most of the nice sights covered for the West Coast. Thanks for the info.
 
#14 ·
Well... you are gambling a bit here.
Twin Towers like to have heavy fog with no warnings and I had driven my Friends there only to see .... parking curbs.
Driving to Tahoe in winter risks road closures. Make sure you carry the chains. Make sure you drive around Emerald Bay, or take paddle boat cruise there. Reno is just a village comparing to Vegas.
Las Vegas is really solid bet for fun, but 2 days are just enough to drive along the Strip and enter couple of casinos. I would make sure to see Bellagio fountain show (every 30 minutes when it is now windy) and Fremont Street show (3 shows every night starting about 8 PM). Nice casinos to enter are Wynns, Bellagio, Monte Carlo and Cesar Palace. Luxor makes architectural impression, but not much excitement comparing to other casinos.
Than I can make a secondary list that would keep you busy for next 2 years.
We go there each year for full week, sometimes 2 and never get bored.
Can't say much about Seattle and Portland. I drove there couple of times but never had time to explore.
 
#16 · (Edited)
Problem Solved.

Thanks everyone for your input.

I decided to switch out the wires to make sure it's not the coil and it worked.
Bad wires so I bought two for $18 each and my problems are solved.

Here's a summary of what i did:

Changed all plugs to Bosch Plat 2
Changed two wires only at the 5 cylinder (G and G wires).
Change my MAS.

Make sure you rent a ob2 reader for your troubleshooting analysis. (very important).

That took care of all my 6 original codes.

Tested drive the car and runs perfect like before :)

Thanks and good luck.

Regards,
JOHNNY.

ps.. heads up for joe for the wire plug suggestion (busoptr).
 
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