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Good evening gentlemen. I have an intermittent misfire on my December 2012 E63 wagon (5.5 biturbo engine with AMG Performance Package - 550 BHP). It first happened about 800 miles back - full throttle, up near the red line, ragged misfire but no EML, felt as though it had gone into some sort of limp mode - no acceleration on more than a small amount of throttle. I pulled over, switched off then on again, and the throttle response was back to normal.
I had the codes read (P0300085 (random misfire), P030685 and P030585 (misfires on cylinders 6 and 5) and P026A00 (charge cooling insufficient) and cleared on Star, but they seemed old stored codes, and there was nothing my (expert) mechanic thought likely to be the cause of the problem. I offered to go and find a stretch of clear freeway and give it some beans, and bring it back with the latest codes. Seven full bore standing start runs up to around 120-130 mph, and....nothing. Everything as normal; no misfire, no problems, nothing.
The misfire came back yesterday. I was doing about 90 mph, and a new Lexus PC200t came hurrying up behind me as I was passing a group of two or three cars, so in order to get out of his way (and, I admit, demonstrate to the poor, deluded fool what real performance looks like...) I floored the loud pedal.
The misfire recurred, the EML came on, the car felt as though it was in some sort of limp mode - open the throttle more than a touch, and it did not want to accelerate. I pulled over on to the hard shoulder, turned off then restarted, and normal running and throttle response was restored with the EML light off. I haven't given it full bore since
I just plugged in the iCarsoft MB II. Four fault codes were stored: P0300085 (random misfire), P030685 and P030885 (now misfires on cylinders 6 and 8) and P026A00 (charge cooling insufficient).
The spark plugs have done 40K miles, so they're not overdue for a change, but if it was plugs or coils, I wouldn't expect the fault to be intermittent.
God, I hate intermittent faults! Could that last code, which points to the IAT/Manifold Temp sensor, relate to random misfiring?
If nobody can shed any light, I'll start with replacing the IAT sensor, and the plugs, and see if it happens again. God, I really hate intermittent faults...
That iat reading is concerning. Did you split your intercooler from your normal radiator setup?
40k miles on the stock plugs may be pushing it a bit honestly. I suspect your plugs are gone
I had a customer's E63 that had a spark plug fail. Find Ground Vision Performance on Facebook and find the picture. The porcelain broke and it could have severely damaged the engine. He had a constant misfire though.
Thanks guys. No, the car is not modified; it's completely standard in every way. So far as the iat sensor code is concerned, I can't see how that could cause an intermittent misfire. I've come to the conclusion that I'll change the plugs and await any further developments; new plugs may sort it out.
I've had the car long enough now to get over the initial "Warp Factor Nine, Mr. Sulu" at every opportunity, so it might be a while before I find out, if ever I do, whether the problem is still there. Time will tell...
Forgot to tell you to check for oil at the ME harness due to wicking up from the cam sensors. I have seen that multiple times and it usually shows up with a misfire.
Forgot to tell you to check for oil at the ME harness due to wicking up from the cam sensors. I have seen that multiple times and it usually shows up with a misfire.
Thanks, guys; first I've heard of that one. Does it usually give a regular misfire, or an intermittent one only under high load?
Based on prior readings, both.
I changed mine before any symptoms could prop up (cheap and easy to do), it was SOAKED in oil! At least 6 to 8 inches of the harness was coated with oil too. Went through 2 cans of crc electric cleaner.
Note I did not have any symptoms yet I had quite a collection of oil. I can only imagine what yours looks like at that mileage with symptoms.
You have a 2012, you could have the first gen plugs that used to cause a lot of misfire even when stock. You definitely have the old cam sensor part number that leaks.
Fix both issues
You have a 2012, you could have the first gen plugs that used to cause a lot of misfire even when stock. You definitely have the old cam sensor part number that leaks.
Fix both issues
My wife's is a '12 also. What's the updated cam sensor? First I've seen a solution other than cleaning/replacing the harness.
Also, hers had a misfire a couple months back. I knew it was time for plugs, having had it tuned last summer, but there was also a coil going out. The stock '14+ plugs are the updated plug for our '12s from what the dealer told me.
The plugs were changed in 2015, but the part number of the replacement plugs fitted (by a main dealer) was 0041596403. I gather that's now the wrong part number; was it the correct plug in 2015? If it wasn't, and the wrong plugs were fitted, then that might explain the misfire...
No need to replace the harness right away, take the ECU out, look at the pins and see if they have oil on them. If not, you are good to replace just the sensors. Do clean the connectors when you replace the sensors, my dealer replaced the sensor with a new one and left the oil in the connector and replugged it back in........smh
Quick search for cam sensor on this forum will show the updated part number. Im not even sure if that is really necessary since IMO they leak after a certain mileage, so change them every 35-40k miles. At $35-4$0 a pop, its cheap insurance
The plugs were changed in 2015, but the part number of the replacement plugs fitted (by a main dealer) was 0041596403. I gather that's now the wrong part number; was it the correct plug in 2015? If it wasn't, and the wrong plugs were fitted, then that might explain the misfire...
Don't know the correct part number for the plugs, but in 2015, they should have already gotten rid of all the old inventory of plugs by then
Ah, the plug part numbers. I now have four possible part numbers for the plugs, but according to Bosch their ZR6SII3320 is/was the standard fitment on pretty much all the MB V6 and V8 petrol engines from about 2012 to 2016! It is tempting to conclude that the MB part number is irrelevant...
I haven't pulled it apart yet; I'll do that when I change the plugs. One question, though; when you say "take the ECU out", do you just mean the connector? What I understand by ECU is the main control unit that the engine harness goes to.
Ah, the plug part numbers. I now have four possible part numbers for the plugs, but according to Bosch their ZR6SII3320 is/was the standard fitment on pretty much all the MB V6 and V8 petrol engines from about 2012 to 2016! It is tempting to conclude that the MB part number is irrelevant...
I haven't pulled it apart yet; I'll do that when I change the plugs. One question, though; when you say "take the ECU out", do you just mean the connector? What I understand by ECU is the main control unit that the engine harness goes to.
I think it is easier to remove the whole ecu and look at the pins outside the car than to try and bend the wiring harness to where you can see the pins under the hood.
Hope this helps. Better have it checked and praying that your still under warranty if this is the problem. Remove your ECU and check connectors to see if you have oil intrusion of any kind as suggestion. If this is the problem and I hope it isn't, it is one hell of a job. It took the dealer more than 1 week with parts and had almost everything taken out the engine for the fix.
2013 E63 with 28,000 miles when it had random misfires and the dealer replaced everything under warranty.
This is a rare thing in the UK so far, and given that I only get a misfire in one particular condition - full load, near the red line, and only intermittently - I suspect I don't have the problem. I'll check the cam sensor connectors when I do the plugs, and hope not to see oil. Fingers crossed...
This is a rare thing in the UK so far, and given that I only get a misfire in one particular condition - full load, near the red line, and only intermittently - I suspect I don't have the problem. I'll check the cam sensor connectors when I do the plugs, and hope not to see oil. Fingers crossed...
You will see oil sorry. But does not mean the harness should be replaced if you do. Cleaning the connectors, replacing the sensors should do the trick (assuming no ecu leakage yet)
It takes about 30 seconds to remove the ME. Why would you not just do that?
I'll be getting at the car next Monday, and I'll check the sensors' connectors to see if there's oil. Two questions, though;
Firstly, where exactly are the camshaft position sensors? I can't find a reliable image anywhere, and the only one I did find that looked right is definitely not for the Biturbo 5.5 M157.
Secondly, could you please confirm what you mean by 'ME'? I presume it is the engine wiring harness (loom on this side of the pond), but I could be wrong.
Changed the plugs; God, it's a fiddly job, but I got there. Now I'll see if the misfire ever comes back...
I found the camshaft position sensors, right at the front of the engine, and yes, they all have oil there, so they'll be changed very soon; thanks for the tip.
04-28-2018, 03:54 PM
