C230 rough idle, no power, misfire code, bad coil, coil test, lessons learned
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c230
C230 rough idle, no power, misfire code, bad coil, coil test, lessons learned
SUBJECT: C230 rough idle no power, misfire code, bad coil, coil test, lessons learned
CAR: 1998 C230
SYMPTOM: very rough idle, car shaking, no power, obvious misfire condition
CAUSE: bad coil (serving cyl 4 and 1)
OBD Codes: P0304 (cyl 4 misfire) + other non related codes
COIL RESISTANCE TEST: (see below)
LESSONS LEARNED - 1) Reset your OBDII codes and restart your engine after each engine modification, else the codes may not update. 2) When a "dual" coil (each coil fires 2 cylinders, 1-4, 2-3) fails the computer may generate a misfire code for only one cylinder not both cylinders (in my case cyl 2 or 4 when the coils were swapped). 3) When you begin troubleshooting a problem, read and record the OBD codes, then clear the codes to remove any "old" codes, then restart the engine and reread the new codes.
MY EXPERIENCE:
Symptom: very rough idle, car "shaking" while idling, no power and shaking while driving, clearly a misfire condition. The check engine light had been on for a long time but the car was running fine until now and the many previous repairs I did didn't require a code read.
I didn't have a code reader so I tried replacing the CAM POSITION SENSOR and that didn't help. So I bought an OBD II code reader and read the following 4 codes: P0450 Evaporative Emission System Pressure Sensor / Switch, P0170 Fuel Trim Bank 1, P0455 Evaporative Emission System Leak Detected (large leak), P0304 Cylinder 4 Misfire Detected. I later found that all but the cyl 4 misfire code turned out to be bogus leftover codes.
Seeing the cyl 4 misfire, I pulled the coil on cyl 4. There are 2 coils, one sits on top of cyl 4 and fires 4 and 1 simultaneously, and one sits on top of cyl 2 and fires 2 and 3 simultaneously ( "wasted" spark system). I didn't think it was the coil because I mistakenly assumed that a bad coil would produce a cyl 4 and cyl 1 misfire since the coil fires both (WRONG!). The spark plug #4 looked fine and I checked the resistance. I swapped the coil packs and also spark plugs 4 and 1 to be sure. I started the car, same symptoms. I read the codes and got the same codes, cyl 4 misfire. I did not reset the codes because the misfire codes are "continuously monitored" and I assumed they would update without being reset (WRONG!). I also made the mistake of not testing the coil with a meter (see below on how to do this).
At this point I figured it can't be the coil, so I pulled the #4 fuel injector wire and confirmed it was getting battery voltage (I did not check the injector firing signal as I didn't have a test light and figured the pulse was too fast to show up on a meter). I replaced the fuel injector, started the car, it had the same symptoms.
What's left - compression? Last thing I would expect. So before buying a compression tester, I figured I clear the codes just to be sure. The coils and also spark plugs #4 and #1 were still swapped. I cleared the codes, restarted the car, and voila! P0302 - cyl 2 misfire, all other codes went away. At this point I again assumed if it was the coil pack it would generate 2 misfire codes since the coil fires cyl 2 and 3 in this position. So I pulled the checked the plug wire boot under the coil and it was fine.
I pulled both coils and did a resistance check with a meter and found a "bad" coil in the now cyl 2 position, it had leakage (high resistance reading) between input positive and gnd and both output+ and ground. The good coil read open (meter set on the highest scale 2000K ohm) between all input and output positives and grounds, which makes sense. Hope this helps someone. In my experience with this car, it's hard to believe that a car this well built has so many problems.
COIL RESISTANCE TEST
Below are resistance measurements for my bad and good coils. Beware, bad coils may produce different resistance results or may not fail until they get hot. Each coil has a coaxial input with a center + pin and outer ground, and two output + pins to the spark plugs.
input+ is the center conductor on the input connector
input- is the outer coaxial gnd on the input connector
output 1 is the center conductor on the bottom of the coil to the spark plug
output 2 is the center conductor on the side of the coil to the spark plug
input+ to input- (this is the primary coil) = 1.8 ohms (bad coil), 1.8 ohms (good coil)
input+ to output1 = leakage ~900K ohms on 2000k scale (bad coil), open (good coil)
input- to output+= leakage ~900K ohms on 2000k scale (bad coil), open (good coil)
output1 to output2 = ~8k ohms (bad coil), ~8k ohms (good coil)
coil boot connector resistance (bottom connector to spark plug): 2K ohms
CAR: 1998 C230
SYMPTOM: very rough idle, car shaking, no power, obvious misfire condition
CAUSE: bad coil (serving cyl 4 and 1)
OBD Codes: P0304 (cyl 4 misfire) + other non related codes
COIL RESISTANCE TEST: (see below)
LESSONS LEARNED - 1) Reset your OBDII codes and restart your engine after each engine modification, else the codes may not update. 2) When a "dual" coil (each coil fires 2 cylinders, 1-4, 2-3) fails the computer may generate a misfire code for only one cylinder not both cylinders (in my case cyl 2 or 4 when the coils were swapped). 3) When you begin troubleshooting a problem, read and record the OBD codes, then clear the codes to remove any "old" codes, then restart the engine and reread the new codes.
MY EXPERIENCE:
Symptom: very rough idle, car "shaking" while idling, no power and shaking while driving, clearly a misfire condition. The check engine light had been on for a long time but the car was running fine until now and the many previous repairs I did didn't require a code read.
I didn't have a code reader so I tried replacing the CAM POSITION SENSOR and that didn't help. So I bought an OBD II code reader and read the following 4 codes: P0450 Evaporative Emission System Pressure Sensor / Switch, P0170 Fuel Trim Bank 1, P0455 Evaporative Emission System Leak Detected (large leak), P0304 Cylinder 4 Misfire Detected. I later found that all but the cyl 4 misfire code turned out to be bogus leftover codes.
Seeing the cyl 4 misfire, I pulled the coil on cyl 4. There are 2 coils, one sits on top of cyl 4 and fires 4 and 1 simultaneously, and one sits on top of cyl 2 and fires 2 and 3 simultaneously ( "wasted" spark system). I didn't think it was the coil because I mistakenly assumed that a bad coil would produce a cyl 4 and cyl 1 misfire since the coil fires both (WRONG!). The spark plug #4 looked fine and I checked the resistance. I swapped the coil packs and also spark plugs 4 and 1 to be sure. I started the car, same symptoms. I read the codes and got the same codes, cyl 4 misfire. I did not reset the codes because the misfire codes are "continuously monitored" and I assumed they would update without being reset (WRONG!). I also made the mistake of not testing the coil with a meter (see below on how to do this).
At this point I figured it can't be the coil, so I pulled the #4 fuel injector wire and confirmed it was getting battery voltage (I did not check the injector firing signal as I didn't have a test light and figured the pulse was too fast to show up on a meter). I replaced the fuel injector, started the car, it had the same symptoms.
What's left - compression? Last thing I would expect. So before buying a compression tester, I figured I clear the codes just to be sure. The coils and also spark plugs #4 and #1 were still swapped. I cleared the codes, restarted the car, and voila! P0302 - cyl 2 misfire, all other codes went away. At this point I again assumed if it was the coil pack it would generate 2 misfire codes since the coil fires cyl 2 and 3 in this position. So I pulled the checked the plug wire boot under the coil and it was fine.
I pulled both coils and did a resistance check with a meter and found a "bad" coil in the now cyl 2 position, it had leakage (high resistance reading) between input positive and gnd and both output+ and ground. The good coil read open (meter set on the highest scale 2000K ohm) between all input and output positives and grounds, which makes sense. Hope this helps someone. In my experience with this car, it's hard to believe that a car this well built has so many problems.
COIL RESISTANCE TEST
Below are resistance measurements for my bad and good coils. Beware, bad coils may produce different resistance results or may not fail until they get hot. Each coil has a coaxial input with a center + pin and outer ground, and two output + pins to the spark plugs.
input+ is the center conductor on the input connector
input- is the outer coaxial gnd on the input connector
output 1 is the center conductor on the bottom of the coil to the spark plug
output 2 is the center conductor on the side of the coil to the spark plug
input+ to input- (this is the primary coil) = 1.8 ohms (bad coil), 1.8 ohms (good coil)
input+ to output1 = leakage ~900K ohms on 2000k scale (bad coil), open (good coil)
input- to output+= leakage ~900K ohms on 2000k scale (bad coil), open (good coil)
output1 to output2 = ~8k ohms (bad coil), ~8k ohms (good coil)
coil boot connector resistance (bottom connector to spark plug): 2K ohms
Member
Joined: Mar 2011
Posts: 78
Likes: 2
From: NJ
2008 ML320 (W164) - 201K Miles
SUBJECT: C230 rough idle no power, misfire code, bad coil, coil test, lessons learned
CAR: 1998 C230
SYMPTOM: very rough idle, car shaking, no power, obvious misfire condition
CAUSE: bad coil (serving cyl 4 and 1)
OBD Codes: P0304 (cyl 4 misfire) + other non related codes
COIL RESISTANCE TEST: (see below)
LESSONS LEARNED - 1) Reset your OBDII codes and restart your engine after each engine modification, else the codes may not update. 2) When a "dual" coil (each coil fires 2 cylinders, 1-4, 2-3) fails the computer may generate a misfire code for only one cylinder not both cylinders (in my case cyl 2 or 4 when the coils were swapped). 3) When you begin troubleshooting a problem, read and record the OBD codes, then clear the codes to remove any "old" codes, then restart the engine and reread the new codes.
MY EXPERIENCE:
Symptom: very rough idle, car "shaking" while idling, no power and shaking while driving, clearly a misfire condition. The check engine light had been on for a long time but the car was running fine until now and the many previous repairs I did didn't require a code read.
I didn't have a code reader so I tried replacing the CAM POSITION SENSOR and that didn't help. So I bought an OBD II code reader and read the following 4 codes: P0450 Evaporative Emission System Pressure Sensor / Switch, P0170 Fuel Trim Bank 1, P0455 Evaporative Emission System Leak Detected (large leak), P0304 Cylinder 4 Misfire Detected. I later found that all but the cyl 4 misfire code turned out to be bogus leftover codes.
Seeing the cyl 4 misfire, I pulled the coil on cyl 4. There are 2 coils, one sits on top of cyl 4 and fires 4 and 1 simultaneously, and one sits on top of cyl 2 and fires 2 and 3 simultaneously ( "wasted" spark system). I didn't think it was the coil because I mistakenly assumed that a bad coil would produce a cyl 4 and cyl 1 misfire since the coil fires both (WRONG!). The spark plug #4 looked fine and I checked the resistance. I swapped the coil packs and also spark plugs 4 and 1 to be sure. I started the car, same symptoms. I read the codes and got the same codes, cyl 4 misfire. I did not reset the codes because the misfire codes are "continuously monitored" and I assumed they would update without being reset (WRONG!). I also made the mistake of not testing the coil with a meter (see below on how to do this).
At this point I figured it can't be the coil, so I pulled the #4 fuel injector wire and confirmed it was getting battery voltage (I did not check the injector firing signal as I didn't have a test light and figured the pulse was too fast to show up on a meter). I replaced the fuel injector, started the car, it had the same symptoms.
What's left - compression? Last thing I would expect. So before buying a compression tester, I figured I clear the codes just to be sure. The coils and also spark plugs #4 and #1 were still swapped. I cleared the codes, restarted the car, and voila! P0302 - cyl 2 misfire, all other codes went away. At this point I again assumed if it was the coil pack it would generate 2 misfire codes since the coil fires cyl 2 and 3 in this position. So I pulled the checked the plug wire boot under the coil and it was fine.
I pulled both coils and did a resistance check with a meter and found a "bad" coil in the now cyl 2 position, it had leakage (high resistance reading) between input positive and gnd and both output+ and ground. The good coil read open (meter set on the highest scale 2000K ohm) between all input and output positives and grounds, which makes sense. Hope this helps someone. In my experience with this car, it's hard to believe that a car this well built has so many problems.
COIL RESISTANCE TEST
Below are resistance measurements for my bad and good coils. Beware, bad coils may produce different resistance results or may not fail until they get hot. Each coil has a coaxial input with a center + pin and outer ground, and two output + pins to the spark plugs.
input+ is the center conductor on the input connector
input- is the outer coaxial gnd on the input connector
output 1 is the center conductor on the bottom of the coil to the spark plug
output 2 is the center conductor on the side of the coil to the spark plug
input+ to input- (this is the primary coil) = 1.8 ohms (bad coil), 1.8 ohms (good coil)
input+ to output1 = leakage ~900K ohms on 2000k scale (bad coil), open (good coil)
input- to output+= leakage ~900K ohms on 2000k scale (bad coil), open (good coil)
output1 to output2 = ~8k ohms (bad coil), ~8k ohms (good coil)
coil boot connector resistance (bottom connector to spark plug): 2K ohms
CAR: 1998 C230
SYMPTOM: very rough idle, car shaking, no power, obvious misfire condition
CAUSE: bad coil (serving cyl 4 and 1)
OBD Codes: P0304 (cyl 4 misfire) + other non related codes
COIL RESISTANCE TEST: (see below)
LESSONS LEARNED - 1) Reset your OBDII codes and restart your engine after each engine modification, else the codes may not update. 2) When a "dual" coil (each coil fires 2 cylinders, 1-4, 2-3) fails the computer may generate a misfire code for only one cylinder not both cylinders (in my case cyl 2 or 4 when the coils were swapped). 3) When you begin troubleshooting a problem, read and record the OBD codes, then clear the codes to remove any "old" codes, then restart the engine and reread the new codes.
MY EXPERIENCE:
Symptom: very rough idle, car "shaking" while idling, no power and shaking while driving, clearly a misfire condition. The check engine light had been on for a long time but the car was running fine until now and the many previous repairs I did didn't require a code read.
I didn't have a code reader so I tried replacing the CAM POSITION SENSOR and that didn't help. So I bought an OBD II code reader and read the following 4 codes: P0450 Evaporative Emission System Pressure Sensor / Switch, P0170 Fuel Trim Bank 1, P0455 Evaporative Emission System Leak Detected (large leak), P0304 Cylinder 4 Misfire Detected. I later found that all but the cyl 4 misfire code turned out to be bogus leftover codes.
Seeing the cyl 4 misfire, I pulled the coil on cyl 4. There are 2 coils, one sits on top of cyl 4 and fires 4 and 1 simultaneously, and one sits on top of cyl 2 and fires 2 and 3 simultaneously ( "wasted" spark system). I didn't think it was the coil because I mistakenly assumed that a bad coil would produce a cyl 4 and cyl 1 misfire since the coil fires both (WRONG!). The spark plug #4 looked fine and I checked the resistance. I swapped the coil packs and also spark plugs 4 and 1 to be sure. I started the car, same symptoms. I read the codes and got the same codes, cyl 4 misfire. I did not reset the codes because the misfire codes are "continuously monitored" and I assumed they would update without being reset (WRONG!). I also made the mistake of not testing the coil with a meter (see below on how to do this).
At this point I figured it can't be the coil, so I pulled the #4 fuel injector wire and confirmed it was getting battery voltage (I did not check the injector firing signal as I didn't have a test light and figured the pulse was too fast to show up on a meter). I replaced the fuel injector, started the car, it had the same symptoms.
What's left - compression? Last thing I would expect. So before buying a compression tester, I figured I clear the codes just to be sure. The coils and also spark plugs #4 and #1 were still swapped. I cleared the codes, restarted the car, and voila! P0302 - cyl 2 misfire, all other codes went away. At this point I again assumed if it was the coil pack it would generate 2 misfire codes since the coil fires cyl 2 and 3 in this position. So I pulled the checked the plug wire boot under the coil and it was fine.
I pulled both coils and did a resistance check with a meter and found a "bad" coil in the now cyl 2 position, it had leakage (high resistance reading) between input positive and gnd and both output+ and ground. The good coil read open (meter set on the highest scale 2000K ohm) between all input and output positives and grounds, which makes sense. Hope this helps someone. In my experience with this car, it's hard to believe that a car this well built has so many problems.
COIL RESISTANCE TEST
Below are resistance measurements for my bad and good coils. Beware, bad coils may produce different resistance results or may not fail until they get hot. Each coil has a coaxial input with a center + pin and outer ground, and two output + pins to the spark plugs.
input+ is the center conductor on the input connector
input- is the outer coaxial gnd on the input connector
output 1 is the center conductor on the bottom of the coil to the spark plug
output 2 is the center conductor on the side of the coil to the spark plug
input+ to input- (this is the primary coil) = 1.8 ohms (bad coil), 1.8 ohms (good coil)
input+ to output1 = leakage ~900K ohms on 2000k scale (bad coil), open (good coil)
input- to output+= leakage ~900K ohms on 2000k scale (bad coil), open (good coil)
output1 to output2 = ~8k ohms (bad coil), ~8k ohms (good coil)
coil boot connector resistance (bottom connector to spark plug): 2K ohms
1) How did you resolve the issue ?. What was the final solution ?
2) Is Coil same as Spark Plug ?. Did you change the spark Plug ?
Thanks
Newbie
Joined: Nov 2013
Posts: 9
Likes: 0
1998 Mercedes-Benz C230
i started having this issue 2 days after changing spark plugs and oil change. I only went under the hood to make sure the new spark plug boot was still intact. Everything was fine before that. I dont know what I could have done in the process. Just wish there was a Car Savior that I can pray to.
Member
Joined: Mar 2011
Posts: 78
Likes: 2
From: NJ
2008 ML320 (W164) - 201K Miles
i started having this issue 2 days after changing spark plugs and oil change. I only went under the hood to make sure the new spark plug boot was still intact. Everything was fine before that. I dont know what I could have done in the process. Just wish there was a Car Savior that I can pray to.
Has similar issue with new Coil, I had to replace new coil.
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Newbie
Joined: Nov 2013
Posts: 9
Likes: 0
1998 Mercedes-Benz C230
Lordofthering, no I did not use BOSCH spark plugs, I used NGK G-POWER PLATINUM but I put the old BOSCH ones back on for now. Two days after, I checked the new spark plug boot which I bought from AUTO ZONE because the old one was melted on the old spark plug in cylinder #2. After checking on that boot and after it was running fine for two days, the CEL came on and these four codes appeard; P0170, P0300, P0302, P0400.
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Member
Joined: Mar 2011
Posts: 78
Likes: 2
From: NJ
2008 ML320 (W164) - 201K Miles
Lordofthering, no I did not use BOSCH spark plugs, I used NGK G-POWER PLATINUM but I put the old BOSCH ones back on for now. Two days after, I checked the new spark plug boot which I bought from AUTO ZONE because the old one was melted on the old spark plug in cylinder #2. After checking on that boot and after it was running fine for two days, the CEL came on and these four codes appeard; P0170, P0300, P0302, P0400.
I would highly recommend you to replace MAF (DO NOT BUY AFTER MARKET Part for this part. ). Cost is around $128 anything less is fake. Very easy to change, if you do not know how to change this part, please do google on MAF and you will find plenty of help. I have tried aftermarket parts and did not work twice.
Below is the part you will need if you have W202. Must buy BOSCH MAF.
Look at this problem similar like you and solved. I believe your issue is bad MAF
http://www.peachparts.com/shopforum/...0173-help.html
Last edited by lordofthering; Jan 14, 2014 at 09:56 PM.
Newbie
Joined: Mar 2017
Posts: 1
Likes: 0
C230
How if code is p0300
I think your issue is Mass Air Flow Sensor not the spark plug. This is most common issue with this car and almost all W202 had this issue at least once. Do you loose power at lower speed ?. Are you having trouble for power during increasing speed at lower speed ?. Once your car is running 40-50 mile/hour, you may not feel much power loss. If that is the case, you need new MAF.
I would highly recommend you to replace MAF (DO NOT BUY AFTER MARKET Part for this part. ). Cost is around $128 anything less is fake. Very easy to change, if you do not know how to change this part, please do google on MAF and you will find plenty of help. I have tried aftermarket parts and did not work twice.
Below is the part you will need if you have W202. Must buy BOSCH MAF.
Amazon.com: Bosch 0280217114 Air Mass Sensor: Automotive
Look at this problem similar like you and solved. I believe your issue is bad MAF
http://www.peachparts.com/shopforum/...0173-help.html
I would highly recommend you to replace MAF (DO NOT BUY AFTER MARKET Part for this part. ). Cost is around $128 anything less is fake. Very easy to change, if you do not know how to change this part, please do google on MAF and you will find plenty of help. I have tried aftermarket parts and did not work twice.
Below is the part you will need if you have W202. Must buy BOSCH MAF.
Amazon.com: Bosch 0280217114 Air Mass Sensor: Automotive
Look at this problem similar like you and solved. I believe your issue is bad MAF
http://www.peachparts.com/shopforum/...0173-help.html
