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DISCUSSION => Engine + Driveline => Topic started by: 318-is on May 30, 2006, 02:25:15 PM

Title: Bizarre m42 fault
Post by: 318-is on May 30, 2006, 02:25:15 PM

my Is has developed a weird fault

from cold and when warm (although it never use to when warm,) my car seems to misfire mostly around corners or from standing starts. The car jolts once or twice extremely violently, but then drives perfectly in a straight line for the rest of the journey. then once i get to a roundabout or a bend, it will randomly missfire once then carry on. It is an intermittent fault, and only coccurs like 4 or 5 times a journey; sometimes it doesnt even happen at all

i also know that my hydrocarbons are high even though i have a new airflow metre on there

besides that, iv brand new coolant temperature sensor from bmw too.

there is no air leaks; all vacuum hoses were replaced less than 10000 miles ago, iv cleaned the injectors too. the throttle body has been refurbished for a big bore one and so is in working condition. iv recenlty changed fuel and oil filters, oil, and brand new spark plugs too.

other than a TPS what else could it be? what gets me is its only really round corners excpet the occasional standing start. i mean in the mornings sometimes it wont start but then any other time of the day, from cold or warm it will start! it also stinks of overfueling? Sometimes in the mornings its fine and others it is not; it really is a random fault!

i shall be trying a new cam sensor end of this week but im fast running out of ideas, as its definatly engine related, not driveline. Assuming its not the cam/crank sensors (i dont see how these would cause overfuelling), anyone else got any ideas to what it could be? maybe fuel pump!?

please help! PLEASE!

Title: Bizarre m42 fault
Post by: Febi Guibo on May 30, 2006, 02:57:36 PM

it could be something as simple as spark plugs (sometimes a small oil leak from the valve cover gasket), an injector heading south... or maybe your fuel pressure regulator...

Title: Bizarre m42 fault
Post by: johna on May 30, 2006, 05:34:10 PM

I had an intermittent misfire where the car would jolt violently, but it happened when the car was under load - nothing to do with cornering. It turned out to be a coil. Maybe something to check.

Title: Bizarre m42 fault
Post by: 318-is on May 30, 2006, 06:48:15 PM

the sparks had no oil on them at all last time i checked!

when its really buggered somedays, it takes a lot of persuasion to start it, it dies on idle, and dies when i put it under load even if i jsut rev it at a standstill and also stinks of fuel. then other days it will start fine but just randomly jolt

il bear the coil in mind!