wondering if someone can help me i have a 2008 JCW
mini cooper works. Couple of years ago i had an issue with timing chain tension-er going which almost cost me an engine but lucky i was not moving at the time BMW changed it free of charge at the time it would have been 1400 euro but they covered the repair as timing chains are not supposed to go. At the time i heard rattle (the chain) figured it needed oil which was low (JCW
does require oil top ups in between services) anyway the chain went very soon after top up but once repaired all was well.
about 8 weeks ago starting the car i heard rattle again ( like a bad diesel engine sound) so dipped it saw it was low and had oil topped up no rattle car running fine but then i started to get few interesting problems over last two weeks. On a cold morning or night start she would start then revs would on there own go up to about 1500 then maybe drop down to 500 ( at this point it would choke itsself out and need restart) again i think i heard rattle but not as heavey almost like lite ticking sound. if weather was not cold she might do the same but not conk out and would correct itself after 30 seconds or so and drive perfectly. I gave it to my local garage who changed plugs and cleaned throttle valve but got it back and first cold morning same problem. Anyway i booked it back in and night before it was to go in i started it and it was cold outside i had same problem but it did not correct itself and when i tried moving car would die, restarted and got it moving but car back fired violently and there was no power felt like 1.1 pulling a tank, went small distance every warning light came on and continued back firing and just died so i parked it up for him to collect. He collected and started it she backfired but as day was warm actually cleared itself after few seconds and drove fine but at least he got to see problem.
He has run diagnostic on it and that's just showing misfire, temp senors seem to be working as is fuel injector and he is having real problems trying to identify the problem the only thing he can think of (after contacting bmw) is to maybe change coils in it.
Today when chatting to a mate who is also mechanic without mentioning history of car just current problems he seems to think its timing chain not tension-ed. would anyone here have an opinion?? i'll say it to my garage monday but if it is chain its a nightmare as in a mini, engine has to come out to get at it. further more if others think it is that problem should BMW cover this as it is out of warranty but timing chain is NOT ever meant to go.
Sorry for long story but i would really appreciate any input from anyone who is expert of cars. I know there are forums with simular to this but they are running to over 100 pages i would just like frank to the point answer if i can get it