james_duro

Hi all, I picked up a 507 coupe about 3 months ago. Ever since I have been chasing this check engine light and multiple misfires.
Mods/Info:
- MBH Headers, Midpipe, Eurocharged V7 tune and K&N Filters.
- Car is a 2015 with 77,000kms

What I've tried so far:
- New spark plugs (OEM from dealer; corrected gap to 0.040"; torqued to 22Nm or ~16ft-lbs)
- New O2 sensors (Bosch OE upstream/primary)
- New ignition coils (OEM from dealer)
- New air filters (K&N, plus removed charcoal filter)
- Cleaned MAF sensors 3 times
- Tested battery with a multimeter (OEM battery replaced 2 years ago)
- Oil changed with Liqui-Moly 5W-40 (Oil cooler drained, OE filter, torqued to spec)

Codes:
- Small EVAP Leak (this is very rare and only happens every 5 or so times I fill up for fuel; doubtful this is related. Maybe a fuel filler neck.)
- Random misfire on multiple/unknown cylinders
- Misfire on cylinders 2,3,4 and sometimes 8

Pretty bad misfiring during cold start. Sounds like a cammed corvette, unfortunately not in a good way.
Also, I know these cars are just awful on fuel, but my dash displays approx. 13L/100KM on the highway in comfort. In reality by tracking km and fuel usage, I am getting more like 19L/100km

Any help on this is much appreciate! I am not a mechanic and may be missing something obvious - I'm all out of ideas.
Thank you!

mr747

Intake manifold leak is your best bet

Dogtag114

My misfire issues ending up being cam adjusters at just over 100k miles.

mwhite1236

Same except mine at 76k miles. I had a cam adjuster rattle on start for a while and then one day car started misfiring and shaking like crazy on highway. Got it towed to my local Indy. Codes were all indicating misfires in right bank. Got the cam adjusters replaced in that bank along with solenoids and sensors. No more rattle on start up and car runs great. (Did new plugs and injectors too for preventative)

james_duro

@mr747 Thank you for the feedback. I will try a smoke test to see if there are any visual leaks.
If I end up removing it, might as well replace the gasket while I'm in there

james_duro

Thank you both @Dogtag114 and @mwhite1236 . I don't have any rattling on startup but I will keep this in mind.
My father's M156 CLS63 needed this back in the day. It only had 10,000km at the time

Nathan Grimmer

If its mapped, its probably over fuelling on cold start, get the map and fueling checked
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mr747

If a tuner is increasing fuel on a cold start on pump fuel then they need to be sacked simple

6_Myles

Experiencing something similar. According to the data is a vacuum, pcv, or intake leak causing my cold start misfire woes.

smoke test and visualyl inspect all the vacuum lines. Also check intake bolts to see if you have a loose one. Don’t tighten it down if so. Get a new one, they are tty bolts