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Over rev.....ouch!

4K views 26 replies 12 participants last post by  PoisonBeef 
#1 ·
Hi guys, was racing my friend in his BMW 330, changed to 3rd gear, thought i was in gear but wasnt. I flattened the accelerator pedal and once i had realised that i wasnt in gear, the revs were already at the end of the dial and the car made a bit of a weird sound. I slowed down and it was idleing very roughly and the car was shaking. I drove to my house really slowly in 1st about 1km away. Was pissed off so i locked the car and went inside. The next morn i checked for boost pipe leaks, oil leaks and found nothing. Started it up, still idleing roughly shaking and sounds like its not firing on all cylinders. Got all upset again and went inside. This morning i started it up, still idleing roughly but not too badly. Drove it to work and by the time i got here it was back to normal, boosting normally and all good. How weird. Was it a limp mode perhaps or what?
 
#2 ·
Most of the time when this happens that valves float and the pistons put a nice kink in the valve stem bending them all making the car run like crap or not run at all afterwards.

I would say count your blessings because it sounds like the car made it by without killing it's self.
 
#4 ·
Look at the plugs. Any extra blowby or oil consumption? Stock pistons don't like being accelerated that fast.

I regularly take my Vig on stock and big cam valve-train to 7200 so it is unlikely that you got it to rev that tight unless in wrong gear. Couple weekends ago saw a drag car 9k in 3rd got to second.. It ruined everything.
 
#5 ·
Look at the plugs. Any extra blowby or oil consumption? Stock pistons don't like being accelerated that fast.

I regularly take my Vig on stock and big cam valve-train to 7200 so it is unlikely that you got it to rev that tight unless in wrong gear. Couple weekends ago saw a drag car 9k in 3rd got to second.. It ruined everything.
Thanks. Going to check the plugs this eve. Think i might just replace them anyway. The car really does seem 100 percent. Thought i had bent a conrod. If i did damage valves, pistons or head then surely it would not suddenly be 100 percent? I thought maybe that by revving it high it over fueled which caused the irratic idleing?
 
#11 ·
I would do as Nick suggest, check each plug, keep track of what hole they came out of and see if one is really wet or anything. Put in a new set of plugs and re-set the ecu and see how it does.

Reading the plugs should tell you some information if there is a problem with one of the cylinders,

good luck,

John
 
#13 ·
As stated before in the thread, if this happened in neutral like he said, the motor should have just bounced of the rev limiter. Can't hurt to check the things stated, but I think the car should be fine.
 
#14 ·
I'd bounce my car off the rev limiter time and time again at autocrosses, as other have said, the rev limit is there, and the only way to exceed it really should be from downshifting instead of upshifting. A no-load trip up to 6500rpm or so should not destroy anything.
 
#15 ·
haha any of you remember Jak Stoll at the Carlisle Show in '06, he was bouncing his car of the limiter non stop.
 
#16 ·
If you pull the plugs and can rotate the engine through, you can look through the spark plug holes with a small flashlight and see the tops of the pistons, this way you could check to see if the valves hit them.
Also, you could do a compression check to see if you have a bent valve (will not seat correctly, therefore low compression).
lastly, you could check to make sure your timing chain did not jump a tooth. This can sometimes happens, especially if components are worn, and will make the car run funny, idle erratic, run hot, etc.. Line up all the timing marks and check.
 
#27 ·
I am fairly sure mine is at 6200. The first time I floored it in my car after having it for a day or two and lost traction, thats where she hit and bounced... I think...
 
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