Had my timing belt, et al, replaced at 58K miles in July of '12 because the chain had too much play in it. Been looking on this list, and from what I can gather it is the tensioner that is causing these premature chain failures. Given when it was replaced, do I have a "new and improved" tensioner, and therefore should not expect any more premature chain failure? Seems like I also read something to the effect that this problem is only with pre '11 vehicles. Is this true?

The check engine light came on, I took it to my independent mechanic, he said the code read that there was intermittent misfiring in the cylinders. His thought was perhaps the timing chain. Car now has 70K on the clock.

Sorry if this has been addressed before. Cheers.

 

Was your whole timing chain system replaced or just the tensioner bolt? When was your last carbon cleaning?

 

The whole system was replaced. I've had all my service done at the dealer (purchased extended service agreement), looked over all the records, and nothing about a carbon cleaning.

 

Sounds like your long overdue for carbon cleaning service. Surprised you've made it this far/miles without it driving you nuts. I'd have your dealer perform a misfire test (cylinder contribution test) which will identify if your vehicle is in need of carbon cleaning services to your intake runners. I'd also recommend @ this point if your their also performing injector cleaning service as well and throw some new plugs in her for the trifecta of service tune up. You will feel like your n14 is alive and new again.

 

my dealer would do carbon cleaning under warranty. ask them about it and they will check for error codes for carbon cleaning.

 

Took her in to the dealer (St. Louis) yesterday, the problem was indeed caused by carbon build up, according to them. Have to reschedule an appt. to get the work done. Service manager said that not using 91 octane fuel could be the culprit. I've been using 89. Opinions?

 

Not really the issue (the octane, though lower than called for(( not sure, 90 for a gen2 car?)) octane COULD cause other issues).....the basic design of the Direct fuel Injection system and PCV system is the problem...
Fuel DOES NOT get sprayed on/near the intake valves like in typical fuel injection....so any PCV gasses and condensate that goes past the intake valves can hit the valves, get baled, and turn to COKE/Carbon.
A redesigned PCV system is helping (mini has changed the PCV design and valve-cover a couple of times), but other manufactures are actually adding 1 extra traditional fuel injector the intake of DI cars..to add a bit of fuel/fuel cleaner to dissolve the gunk before it can bake....remember, on a DI injected car, the INJECTOR is SCREWED INTO the HEAD of the car, like a sparkplug, and it operates at very high PSI, unlike a traditional Fuel injection, where it is injected just prior to the intake valves...