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< Solved> W203 Random Misfire - ODB2 result attached C320 2002
< Solved> I have a serious unstable idling issue with C320 2002, 180K miles. Idling is so unstable, so that the engine stops sometimes while idling, a lot of vibration. Over 1500RPM, the engine seems to be running OK.
1. Fuel pressure is OK, tested. Fuel filter, pump, CPS are replaced.
2. All plugs are replaced. The coils were swapped, and no change on the error code.
3. MAF was cleaned. When MAF was disconnected, the same symptom persists.
Could be the injectors.
If it's not too hard, swap #1 and #2 injector.
Also, do a compression test. Again, just doing #1 and #2 will tell give an indication. If they differ by more than ~5%, then test all of the cylinders.
How exactly was the MAF cleaned? The design isn't exactly conducive to cleaning and spraying anything in these is more likely to do harm than good. If there was no change after cleaning I would guess your MAF was already dead. Can you see MAF live data with your obd2 code reader?
Could be the injectors.
If it's not too hard, swap #1 and #2 injector.
Also, do a compression test. Again, just doing #1 and #2 will tell give an indication. If they differ by more than ~5%, then test all of the cylinders.
I can't perform compression test here, but I'll swap injectors today. Thanks!
How exactly was the MAF cleaned? The design isn't exactly conducive to cleaning and spraying anything in these is more likely to do harm than good. If there was no change after cleaning I would guess your MAF was already dead. Can you see MAF live data with your obd2 code reader?
Thanks!
I cleaned it with CRC MAF Spray. After cleaning, the symptom is the exactly the same as before, and the same when MAF is connected or disconnected, so I guessed it would not be MAF. No live MAF data unfortunately.
I just disconnected Alternator, and the engine idling is smooth now.
I think it's Voltage regulator that is shorting or sending wrong voltage when the engine is slow.
I'll change voltage regulator next week. Thanks a lot!
Thanks!
I cleaned it with CRC MAF Spray. After cleaning, the symptom is the exactly the same as before, and the same when MAF is connected or disconnected, so I guessed it would not be MAF. No live MAF data unfortunately.
Turn the key to position 2, click the odometer reset button 3 times and you should see the voltage. Drive the car with that displayed and alternative connected. If the alternator VR is the problem like you suspect you should see some wold variations in voltage. Normally voltage should stay between 14.0-14.5 with the engine running.
Turn the key to position 2, click the odometer reset button 3 times and you should see the voltage. Drive the car with that displayed and alternative connected. If the alternator VR is the problem like you suspect you should see some wold variations in voltage. Normally voltage should stay between 14.0-14.5 with the engine running. https://youtu.be/ge1SgCZAXh0
I'll test the voltage in this way later.
The live data from ODB2 is showing the voltage between 11.2-13.2V while running, so I think VR or Alternator is causing the issue. I ordered VR, hoping it will solve the problem, finger crossed... Thanks!
I'll test the voltage in this way later.
The live data from ODB2 is showing the voltage between 11.2-13.2V while running, so I think VR or Alternator is causing the issue. I ordered VR, hoping it will solve the problem, finger crossed... Thanks!
When u get the VR make sure the small 2 pin plug is identical to yours. When I got mine, the seller shippede a w211 VR instead which looks identical but that small plug is slightly different and wouldn't fit. I only realized this after reinstalling the alternator. It was a waste of time.
The alternator on the c320 can be removed from the front by moving some the aux coolant pump to the side. You don't have to drain coolant or disconnect anything. Remember to disconnect the battery. Good luck.
When u get the VR make sure the small 2 pin plug is identical to yours. When I got mine, the seller shippede a w211 VR instead which looks identical but that small plug is slightly different and wouldn't fit. I only realized this after reinstalling the alternator. It was a waste of time.
The alternator on the c320 can be removed from the front by moving some the aux coolant pump to the side. You don't have to drain coolant or disconnect anything. Remember to disconnect the battery. Good luck.
1. I have changed voltage regulator, still low voltage. My alternator is not Bosch.
2. I have changed whole alternator ($130@Amazon), voltage goes up to 14.3V, and vibration is much less than before.
3. After "Italian Tuneup" (5000RPM driving for 5-10 miles), vibration has mostly gone.
03-02-2018, 04:02 PM
