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So I just got 2014 E63s with 86k miles about a month ago. I ran into a cylinder 1 misfire a few days after owning the car. I did all brand new spark plugs and gapped them to .022 and also did a fuel induction cleaning. About 1000 miles later I got cylinder 5 misfire. I cleared that and now about 500 miles later I know got cylinder 1 misfire. So it looks like it's going back and forth not sure what could be causing it. I'm going to reach out to Renntech again and see what they advise. My friend at Mercedes said we are going to do software updates and flash the ecu back to stock and run the car like that for a while and see if it comes up again. Just trying to see if the Renntech tune is causing issues with the ecu.
The car has Renntech R1 package as far as mods good.
If anyone has has this issue or if anyone has any ideas on what else I should be looking at I would greatly appreciate it.
Oh I should add,this only happens after going Wide open throttle, and the cel starts flashing then it goes solid and stays on. If I turn off and on the car the cel goes away. I used my Carly device to run the codes.
If this goes away after you go back to stock ECU, then you might want to make sure of your gas quality, i.e., it might not be high enough octane for your tune. If not, you might wanna try replacing your coils as well.
the m157 motor When tuned is very fussy about fuel quality and octane. If you have access to 100 octane fuel near you I would drop three or 4 gallons in with whatever fuel you’re running and see if that eliminates the misfires.
I use Shell 93 octane in all my cars. I don't have access to 100 octane in the Northern VA area. Just e85 but I don't think the car can run that. I could buy some octane booster and use that for now. I did jinx myself though. Now the CEL is still on it didn't reset when I turn off the engine and restarted the car.
OEM Plugs which were gapped to .022 like Renntech Recommends.
I use Shell 93 octane in all my cars. I don't have access to 100 octane in the Northern VA area. Just e85 but I don't think the car can run that. I could buy some octane booster and use that for now. I did jinx myself though. Now the CEL is still on it didn't reset when I turn off the engine and restarted the car.
OEM Plugs which were gapped to .022 like Renntech Recommends.
youll have to clear it with an obd2 device while the car is in the on position but engine not on
Yea i got it to work now with my Carly. I'll do some more runs tomorrow and see what's going on. I added some octane booster earlier.
When you pull your plugs, is there any blowback on the plugs? I was getting misfires with a newly installed r1 renntech package with new oem plugs gapped to .022 and pulled the plugs 2 weeks later to find oil blowback on the plugs so its likely piston rings are done and misfires would only happen at the upper edges of the r1 package boost. in effect having the tune allowed me to diagnose the issue earlier than i would have been able to otherwise bc it doesnt misfire at stock boost levels yet (just a matter of time). Its not as much a problem for me bc i have a warranty that should cover, but hopefully this isnt the issue for you.
Well since we did the plugs about 1000 miles ago my friend who is a master tech at Mercedes checked the previous plugs and didn't notice any blowback. I think we are going to start with replacing the Ignition Coil first and we will recheck for any signs of blow back and I guess go from there. If anyone else has any input please let me know, I appreciate everyone's so far. I already ordered the Coil from FCP Euro so I should have it within the next couple of days.
Hey thabigo
Been a while since you posted this...I can’t believe I didn’t see this post until now. Purchased a 2014 e63s with the RennTech stage 1 tune in Sept 2019. Have been having misfire issues ever since - only under WOT and intermittently.
Changed plugs with cooler model at local RennTech specialist and issue persists but less frequently. RennTech advised to purchase updated tune - which I did. No change.
Hey thabigo
Been a while since you posted this...I can’t believe I didn’t see this post until now. Purchased a 2014 e63s with the RennTech stage 1 tune in Sept 2019. Have been having misfire issues ever since - only under WOT and intermittently.
Changed plugs with cooler model at local RennTech specialist and issue persists but less frequently. RennTech advised to purchase updated tune - which I did. No change.
Did you ever have luck addressing your misfires?
For me the solution was to make sure you use OEM Spark Plugs and gap them at .022. I tried using the Bosch Spark Plugs through FCP Euro and those died within 5k miles instead of the 9k-12k miles your suppose to get with the OEMs. That was one of my issues. The other one that I had was the front O2 sensors. I kept getting intermittent misfires and no codes reading the o2 sensors. My tech was monitoring them with the Xentry system and determined that they were faulty. So far so good and no more misfires. I still got my CEL from the catless downpipes which have spacers so the CEL turns on every now and then kinda a PITA so I would get catted DPs next time for sure. Renntech won't tune it out unfortunately since they aren't about messing with emissions.
Wow - thanks for getting back to me!
stock plugs and O2 sensors. Check.
I was about to have the RennTech - spec plugs installed again (been about 7k miles). Based on your recommendation, I’ll do stock and swap out the O2s as well. Thank you very much for the insight.
re: your CEL and the downpipes - thanks for that insight as well. Ultimately, I really wouldn’t care if the CEL pops on every so often as long as it doesn’t go into limp mode like with the misfires. Sounds like you have a fun ride - congrats! And thanks again for the pointers
Prob gonna be a month or two until I get to the plugs...but I’ll post back.
I had the same issues with my W212. IT WAS BAD FUEL. Somehow I got a bad batch of fuel. After burning it off, I filled with Chevron (not Shell) and never had a problem since. YMMV
For me the solution was to make sure you use OEM Spark Plugs and gap them at .022. I tried using the Bosch Spark Plugs through FCP Euro and those died within 5k miles instead of the 9k-12k miles your suppose to get with the OEMs. That was one of my issues. The other one that I had was the front O2 sensors. I kept getting intermittent misfires and no codes reading the o2 sensors. My tech was monitoring them with the Xentry system and determined that they were faulty. So far so good and no more misfires. I still got my CEL from the catless downpipes which have spacers so the CEL turns on every now and then kinda a PITA so I would get catted DPs next time for sure. Renntech won't tune it out unfortunately since they aren't about messing with emissions.
Happy to hear you resolved the misfires! Most tuners do recommend replacing plugs sooner when tuned versus stock, also.
Thanks again for the reply back in April. Since then my shop actually rented a local drag strip and I purchased a few pails of Sunoco 100 octane race fuel for the event. Ran the tank way down and filled 1/4 way up.
Took the ECU about 7-10 miles of spirited highway driving to remap...during which, any time 3/4 throttle or higher I had misfire codes. BUT - after 7-10 miles, it was rock solid under all throttle conditions. Actually pulled an 11.18 in the 1/4 mile! (slip pictured).
With the RennTech site suggesting the R2 kit would do 11.61, I was pretty surprised seeing as my vehicle has the lesser R1 package. So...to me, the prior issues with WOT acceleration now seemed like a fuel issue.
Since then I've been running 1-2 ounces of a product called Boostane Professional and have had no misfire codes....for the first time in the 20 months I've owned the vehicle. I know lots of members here would say not to use octane enhancers/boosters and my local RennTech specialist also initially was of the same opinion. But with about a month of very spirited driving and no misfire codes, I'm going to stick with what works! It's been a month tomorrow since I had a misfire code and, man, have I been enjoying stomping my foot on the pedal and running well into triple digits (open roads) with no issues. What a machine.
thabigo22 - thanks again for your great insight here. Should I have issues with misfires in the future, I will remember to look at the O2 sensor(s).
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