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Various Cylinder Misfires

52K views 136 replies 36 participants last post by  scrisp78 
#1 ·
Is anyone getting random cylinder misfires on their 12C? I have it happening just after the engine is warmed up and I have to idle at a redlight...quite annoying. I get a blinking check engine light that occasionally goes solid. It clears after a couple of starts or I clear it from my Dash Command App and a Pixi II ODB cable (at the instruction of my McLaren dealer).

I don't like this constantly occurring and wanted the groups 2 cents.
 
#3 ·
I've had that off and on for a few months now. I mentioned it to my dealer and they looked into it but there wasn't a clear solution and it still occurs every now and again. Coincidentally it actually occurred for me today at a stop light. Sorry I don't have more info for you, but if you find anything else out, it would be great to hear.
 
#5 ·
The dealer said they thought bad gas but this is a recurrent problem over 4 months. FWIW I only use Shell VPower 93 Octane (same as 98 RON). The issue is more a nuisance than a serious issue as it does not reduce power or give me the death warning telling me to call the dealer. It is just a disconcerting feeling every time the check engine light starts to blink.

I just had the Ver 12 software update which fixed several glitches for the better but sadly this was not one of them. I will keep you all posted if I find a solution.
 
#8 ·
yes yes ! i keep getting this . I get lean codes and flashing engine light . Car runs fine but when i turn car on i get this . Dealer cant figure it out and keeps changing parts with no solution .

I already did all gas even 100 oct . and all fuel additives . Changed plug they even replaced a few injectors . and coil packs
 
#10 ·
Did they change the oxygen sensors? Would be my guess....

yes yes ! i keep getting this . I get lean codes and flashing engine light . Car runs fine but when i turn car on i get this . Dealer cant figure it out and keeps changing parts with no solution .

I already did all gas even 100 oct . and all fuel additives . Changed plug they even replaced a few injectors . and coil packs
 
#12 ·
Here are the codes:
P0300 - Random/Multiple Cylinder Misfire Detected
P0308 - Cylinder 8 Misfire Detected
P0305 - Cylinder 5 Misfire Detected
P0307 - Cylinder 7 Misfire Detected

This always clears itself after a day or two or if I reset the CEL
 
#17 ·
It just hit me, remembering a white sheet on the engine posted in another thread, there a 4 knock sensors on the engine and one is directly between cyl 5&7. Depending on the fuel delivery system and hot spots in the engine there could be an intermittent knock at the front of the engine, specifically around 1 or 2 cyl that knocks a little under acceleration when timing is being advanced. Cyl 8 may be sending the knock from 7, but doubtful. Many engines have hot / lean cylinders and require a custom tune to fatten up one or 2 cylinders to prevent this lean/ knock condition. I'd like to think McL would have found this during development. Fuel flow and heat are the root causes of this if this is intact the issue. A knock can be interpreted as a misfire by the ECU.

Just thinking out loud.
 
#25 ·
The plugs on mine were replaced at 22000 Miles as the result of a error message that was read out.


If you are interested in more details:
Spark replacement was the result of 3 weeks diagnostics at McLaren dealer here in Brussels.
My 2013 Spider had quite a irregular cold start. Afte 3 secs the engine seemed to stutter down to 600rpm and then up to 2500rpm and down again and up .... during 2 following minutes, but not when I started driving... immediately after 5 secs.
I some cares in the first 5 minutes of driving, the car would tremble while in high gear at low speeds when I pushed the pedal, 5 th or 6th gear at 30 miles/hour. Then the engine light would blink for 30 secs and then go away.

With these facts, I left it weeks at the shop with my suggestion of a possible problem with the driveline dampers.
I read on DLD issues in another forumthread about irregular cold start.
DLD change is a serious expensive job so Mclaren warranty service let them do all sorts of tests, resets, but they couldnt find any error message of any kind. Except my car tremble error seemed to have been reported as a misfire error. This lead them to replace all sparks, a 650usd job not covered by warranty...although they should normally be replaced at 50000miles...

the irregular rpms at cold start where still there, painful feeling:crying:
but the car trembling didn’t happen anymore.
After 1500 miles to and from the Italian alps via Germany, the cold startup is not irregular anymore, great I think.
But today the car trembling and engine light issue is back, way longer and I had to stop/start the car. :crying:

So also
 
#28 ·
Something nobody has mentioned but I've seen happen in other cars... air filters. Have air filters been checked? Clogged filters will choke it at idle, cuts off air, fuel adjusts down to compensate, misfires.
 
#30 ·
Hey, I would check the vac harness, If you check where the vac harness fits onto the Left hand turbo dump valve to the waste gate as these do sometime come away from these area. I worked from Mclaren and Mclaren GT for a number of years and these was a common problem. It's a pain to get to the dump valve pipe on the left hand turbo but a good one to check.
We did also have issues with the wiring looms, so also check the connectors which clip to the oil filter housing in case any damage/oil after an oil filter change has happened, as we would sometime get these misfire problems with the engine wiring looms due to heat. So the main engine wiring loom has the coils all in built and the injections have a small separate loom for each side of the engine.
Hope this helps.
 
#31 ·
Hello folks, I’m new to the forum and I was hoping that someone here had the same issue and found the problem.
I took my car to the mclaren of SF for a basic oil change, after getting the car delivered back to my work, the car has a huge misfire on bank 5,6,7 and 8 (left side of the engine) and it the engine will shake, rpm will fluctuate during idle as well doing a valve noise due the fluctuating RPM (sounds like a lose nut on the bottom metal pan)
Own the car for 2 years and never had any issue whatsoever. I’m not sure if it’s related to the oil change or just a coincidence. The weird metal noise and misfire disappears during cold start, it will appear once the engine warms up.
Tried to look everywhere for a lead or a tip to find solution for this issue but no luck.
I find very odd to be misfiring on all the cylinders on the driver side of the engine. Also very odd to appears right after an oil change which technically speaking should have nothing to do with the misfire.
If anyone can help, I greatly appreciate it. Thanks guys!
 
#32 ·
So I replaced all spark plugs, switched the ignition coils, o2 sensors, maf sensors, intercooler pressure sensor, replaced air filters and the car still misfires on cylinder 5,6,7,8. The whole bank is misfiring. Only misfires on idle. No misfires when engine is cold or at high RPMs. Very weird and annoying to diagnose. Obviously mclaren of San Francisco will always recommend a new engine or even a whole new car. I’m just trying to work all my options before I do anything else to it. Anyone can help? Any tip? Anything I’m forgetting to check????
 
#40 ·
Thank you guys. I’ll start with the compression test then I’ll check the springs and dampers. Have you guys used the XPRD shop? Are they knowledgeable with opening engines? I don’t want to take to mclaren again because I know they will diagnose the easiest: just change the whole engine and even the whole car. My car always ran fine with no issues whatsoever. It has 31k miles and I hate to see this happen to it.
 
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