2009 Clubman S 135,000 miles. Cruising down the highway at 80mph and it starts hesitating. I scan it with my phone app and it says cylinder 1 misfire. The CEL is flashing. Then all hell breaks loose. All cylinders are misfiring. I get home and change out all the plugs and coils. (saved from the pervious swap in Jan 2019) Start it up and my Swaben says cylinder 3 misfire. High pressure fuel pump shut off. I reset all the codes. Install new plugs and coils. Again cylinder 3 misfire.

Questions: What are some of the causes for the same cylinder to misfire? Is there something common at this mileage?

Any ideas, comments, greatly appreciated

Thanks Frank

 

Got this code 2B64 unmetered air. Things I have checked so far. Timing chain and guides, Vanos, PCV, all look ok. Looked inside the cylinders as best I could with a flashlight. Couple of cylinders looked like it could be wet on the top. Hard to say. Cylinder 1 looked like there was some black gunk on top. Like I said hard to tell and I have nothing to compare it too because I've never had an issue like this.

 

Bump

 

The misfire with #3 cylinder may be self inflicted. I note the misfire moved from #1 to #3 after you replaced the plugs and coils.

This suggests that something is amiss -- no pun... -- with the connection of the coil to the plug or with the coil to the engine wiring harness. The coil must be properly secure so it has a very good ground.

I'd suggest you double check your coil/plug work.

If you find nothing to account for the #3 cylinder misfire you probably want to focus on the unmetered air issue.

The intake system is a pretty complex air flow device and anything out of the ordinary could account for a cylinder misfiring. The other cylinders may be close to registering a misfire it is just the #3 cylinder gets over the threshold first.

No direct experience but with two people I know who both had cars that generated a persistent misfire one was caused by an over rev of the engine -- apparently there was no rev limiter to protect the engine and a valve floated and touched a piston and was bent.

In the case of the other car at something over 100K miles an exhaust valve burned. This was a turbo charged engine (Subie car) and exhaust valves can run pretty hot.

In both of these cases were one applicable to your engine a compression test would likely find a low cylinder pressure in the #3 cylinder. If adjacent cylinders are low that could be a head gasket leak between cylinders.

While I've never encountered a bad injector techs have told me a lazy injector can cause misfires. I have never had to touch injectors and I'm very reluctant to mess with these unless it is clearly necessary and am just as reluctant to send you on an injector R&R but if you find no other reason to account for the misfire behavior...

 

Thanks for your response. I had it towed to the dealer. It starts and runs, just not very well. I'll report back with the diagnosis. Hopefully I won't get clobbered!