Multiple random misfiring P0300
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Multiple random misfiring P0300
Please advise, I have been diagnosing the CEL P0300 of my 2011 E63 with 45,000 miles and have not found any solution. The multiple cylinder misfiring are cylinder 1, 2, 3 and 4 all in Bank 1. The engine idles normally and when I rev the engine, the engine response well and responsive. However, when there is a load (driving the car) the check engine lights turns on and engine runs rough and no power.
I have switch over spark plugs, coils, cam shaft sensors to the Left Bank (Driver's side) no improvement. I checked on the fuel pressure and the reading at idle was as 50 psi and when I rev the engine at 3000 rpm the reading was 60 psi. I have loosen the exhaust pipe thinking that the catalytic converter might be clog but no changes. I checked all Bank 1 fuel injectors by disconnecting the electrical connector one by one and as I disconnect the connector the engine idles changes, meaning the injectors are working. I have sprayed carburetor cleaner around intake manifold and vacuum hoses, no leaks. I am hoping that someone in this Forum can give me some advise how to solve this problem. Thank you in advance
I have switch over spark plugs, coils, cam shaft sensors to the Left Bank (Driver's side) no improvement. I checked on the fuel pressure and the reading at idle was as 50 psi and when I rev the engine at 3000 rpm the reading was 60 psi. I have loosen the exhaust pipe thinking that the catalytic converter might be clog but no changes. I checked all Bank 1 fuel injectors by disconnecting the electrical connector one by one and as I disconnect the connector the engine idles changes, meaning the injectors are working. I have sprayed carburetor cleaner around intake manifold and vacuum hoses, no leaks. I am hoping that someone in this Forum can give me some advise how to solve this problem. Thank you in advance
Last edited by hcsoong; Oct 7, 2016 at 04:07 AM. Reason: adding more tests
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2014 Gl350 Bluetech (Diesel) , 2007 ML350 3.5L V6 Gas
I have similar P0300 multiple misfire on bank 1 cylinder 1,2&3 on 2007 ML350 V6. Wondering if you ever got yours fixed and what was the culprit? My scan codes indicate that all the injector electrical circuits fault or open, plus camshaft sensor A&B on bank 1 electrical circuit fault or open. they are all on bank 1! By listening to the injectors for click or zip, can tell they are not firing most of the time, cylinder 1 & 3 fire occasionally which would rev up idle momentarily, which has been at very low 600-800 rpm, barely hanging-on and sometimes dies.
Checked on the 3 injectors, they are all working - with 12vdc to 2 terminals, they click. Injector wire harness/connector w 2 terminals, one terminal has 12V, the other/signal terminal has rarely anything.
I am wondering is it's due to electrical - wire shorts or open, or computer, or the bank 1 Cat converter clogged? Really appreciate anyone who's experienced similar situations or with the issues to provide comments or suggestions. Thanks much in advance!
Checked on the 3 injectors, they are all working - with 12vdc to 2 terminals, they click. Injector wire harness/connector w 2 terminals, one terminal has 12V, the other/signal terminal has rarely anything.
I am wondering is it's due to electrical - wire shorts or open, or computer, or the bank 1 Cat converter clogged? Really appreciate anyone who's experienced similar situations or with the issues to provide comments or suggestions. Thanks much in advance!
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Joined: Nov 2011
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From: Austin, TX
2013 SL550 BiTurbo
I have similar P0300 multiple misfire on bank 1 cylinder 1,2&3 on 2007 ML350 V6. Wondering if you ever got yours fixed and what was the culprit? My scan codes indicate that all the injector electrical circuits fault or open, plus camshaft sensor A&B on bank 1 electrical circuit fault or open. they are all on bank 1! By listening to the injectors for click or zip, can tell they are not firing most of the time, cylinder 1 & 3 fire occasionally which would rev up idle momentarily, which has been at very low 600-800 rpm, barely hanging-on and sometimes dies.
Checked on the 3 injectors, they are all working - with 12vdc to 2 terminals, they click. Injector wire harness/connector w 2 terminals, one terminal has 12V, the other/signal terminal has rarely anything.
I am wondering is it's due to electrical - wire shorts or open, or computer, or the bank 1 Cat converter clogged? Really appreciate anyone who's experienced similar situations or with the issues to provide comments or suggestions. Thanks much in advance!
Checked on the 3 injectors, they are all working - with 12vdc to 2 terminals, they click. Injector wire harness/connector w 2 terminals, one terminal has 12V, the other/signal terminal has rarely anything.
I am wondering is it's due to electrical - wire shorts or open, or computer, or the bank 1 Cat converter clogged? Really appreciate anyone who's experienced similar situations or with the issues to provide comments or suggestions. Thanks much in advance!
The other major issue with that motor is the harness get oil intrusion from the cam phase sensors on the front of the head. Pull the connector and check for oil. if that is the issue, then you got it bad...hopefully that is not the case.
After these two things, I would start looking to have the engine scanned with a MB specific scanner that can talk to and retrieve/clear codes from ALL the modules as OBD2 scanners cannot. I have this . It cannot actuate or change any parameters, but it will read and clear all codes in the system. Good luck.
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2014 Gl350 Bluetech (Diesel) , 2007 ML350 3.5L V6 Gas
nota_amg: thanks much for the comments. I will try the rubber hammer test.
The camshaft sensor connectors are fine - fairly dry and clean, sensors replaced within a year.
I have a Bluedriver Pro Scanner, able to scan and clear all Mercedes codes. 3 consistent ones are injector circuit fault/open for all bank 1 cylinder 1,2 & 3. Test-light verifies that the 3 wire terminals are not firing most of the time. I am leaning towards electrical as bank 1 camshaft sensor circuits are open as well per codes.
Next step, I'd try tracing the wires back to the ECU pins and testing them for firing signals. Could be the ECU if the firing signals are not correct. Does it make sense?
Are there relays or fuses specifically for the fuel injectors? I've checked all of them that I thought relevant.
There has been no codes scanned related to O2 sensors or catalytic convertors somehow!
Again, thank you so much for your inputs on this. sooner or later we'll nail it!
The camshaft sensor connectors are fine - fairly dry and clean, sensors replaced within a year.
I have a Bluedriver Pro Scanner, able to scan and clear all Mercedes codes. 3 consistent ones are injector circuit fault/open for all bank 1 cylinder 1,2 & 3. Test-light verifies that the 3 wire terminals are not firing most of the time. I am leaning towards electrical as bank 1 camshaft sensor circuits are open as well per codes.
Next step, I'd try tracing the wires back to the ECU pins and testing them for firing signals. Could be the ECU if the firing signals are not correct. Does it make sense?
Are there relays or fuses specifically for the fuel injectors? I've checked all of them that I thought relevant.
There has been no codes scanned related to O2 sensors or catalytic convertors somehow!
Again, thank you so much for your inputs on this. sooner or later we'll nail it!
