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Discussion Starter · #1 ·
A buddy of mine who works for a BMW dealership in my town told me that if I find a M5 that is still under factory warranty, I have to make sure it doesn't have any over rev codes in the computer. If something should happen to the engine and the service techs go in an find any over rev codes, then I am stuck with the bill. Is this true? Second, does one get a code from simply going over red line on rpm's for a second, or will it not register unless certain parameters are met like being rev'ed too hard for an extended period of time.

I did a search and couldn't find anything, but wanted to make sure there were no surprises on any hopeful purchase in the next week.
 

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jlindy said:
A buddy of mine who works for a BMW dealership in my town told me that if I find a M5 thWhat is still under factory warranty, I have to make sure it doesn't have any over rev codes in the computer. If something should happen to the engine and the service techs go in an find any over rev codes, then I am stuck with the bill. Is this true? Second, does one get a code from simply going over red line on rpm's for a second, or will it not register unless certain parameters are met like being rev'ed too hard for an extended period of time.

I did a search and couldn't find anything, but wanted to make sure there were no surprises on any hopeful purchase in the next week.
Interesting... what effect does the computer rev. limiter play? Fuel is cutoff when you reach too far into the red.
 

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Fuel cutoff won't help you on a 5th to 2nd (instead of 5th to 4th) blown shift forcing the engine to rev to 12,000 rpms and then kaboom....

Rev limiter can't stop the engine from turning those revs if the drivetrain is forcing the engine to spin that fast.
 

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I would hope that under a severe mis-shift (like a 5-2) the car would lose traction and the rear tires would simply stop turning (skid). I know this happened to me on a previous car, but not sure if the meat on the M5 would do the same...
 

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Wrightsville's post is how I understand the system to work. The rev limiter will protect you if you just keep your foot in it too long, but can not protect you from the mechanical problem of a improper downshift. It's only a software program, not a brake on the driveshaft.
 

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You got it.

I used to do some minor wrenching for a guy that raced superbikes. He was extremely hard on downshifts - usually pushing the limit with little mechanical sympathy for the drivetrain.

The rev limiter would prevent him from over-revving if he simply held on to the throttle too long in gear - but it wouldn't help him if he got too aggressive banging downshifts into a turn and overrevved the engine.

Invariably he would cook a motor or two each season by downshifting too aggressively and spinning the engine past its mechanical limits.
 

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I would rather not identify an M5 owner that got nabbed by over-rev events being recorded in the BMW DME computer. Be advised that at least one person got in a big battle with BMW over who should cover an engine that showed non-OEM rev limits exceeded & threw parts. An aftermarket chip was removed before the warranty request was filed.

I witnessed first hand discussion on this subject. It is true and the risk of warranty forfeiture is real. Folks choosing aftermarket chips with elevated RPM limits are assuming risk. If the engine sees an internal hardware failure, they will most likely review "excess RPM event history" stored in the engine mgmt computer.
 

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LSCMAN,
Do these over rev codes show on the "normal" code readout, just like an O2 sensor or other code?

:cheers:
 

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Lscman said:
If the engine sees an internal hardware failure, they will most likely review "excess RPM event history" stored in the engine mgmt computer.
The follow up seems to be, how does one remove the stored codes absent going to a dealer? If they are not removable, are they overwritten after a certain amount of time/engine revs?
Regards,
Jerry
 

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Lscman said:
I would rather not identify an M5 owner that got nabbed by over-rev events being recorded in the BMW DME computer. Be advised that at least one person got in a big battle with BMW over who should cover an engine that showed non-OEM rev limits exceeded & threw parts. An aftermarket chip was removed before the warranty request was filed.

I witnessed first hand discussion on this subject. It is true and the risk of warranty forfeiture is real. Folks choosing aftermarket chips with elevated RPM limits are assuming risk. If the engine sees an internal hardware failure, they will most likely review "excess RPM event history" stored in the engine mgmt computer.
Chip? What chip? :confused:

Lscman, there is much I would rather not talk about on this board. I never missed a shift in the M5 while I owned it. There is a lot more to this story, but things are so fine and dandy with Porsche and its GT cars, there's no reason to look back into the dark past. ;)

That being said, it is definitely not recommended to raise the rev limiter on these engines. They are just too maxed out from the factory. The engine is simply not meant to be revved past 7100rpm for any sustained period.

BMW will try to find any excuse to get out of a warranty claim, period. They only changed their minds when they found out that my family is full of litigation attorneys. Had a CHIP company been found responsible, they would have paid for a new engine and then some after my legal team got done with them. grrrrrrr
 

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Discussion Starter · #11 ·
I just wanted to get back to my question. How much is enough to set them off? If I find a vehicle that has some codes in it's computer, should I walk away from the vehicle because the warranty may be void or no? This is more for pre-purchasing than maximizing speed/power through rev limiters and/or chips. Thanks.
 

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FYI. I had an '02 turbo Jetta. Right before selling, I took the car in for a cel which turned out to be an o2 sensor. They asked me if the car had been chipped and of course it wasn't. It was completely stock :D . Well, turns out they asked because they found an over-rev code (or several). I guess with that and the prior first/second gear rebuild, they got suspicious. Anyhow, they made me sign a disclamier that the car was never chipped or modified in any way. If I didn't, they would have made me pay the repairs and void the warranty. I signed, sold the car and moved on to an M5. So yes, they can tell.
 

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jlindy said:
I just wanted to get back to my question. How much is enough to set them off? If I find a vehicle that has some codes in it's computer, should I walk away from the vehicle because the warranty may be void or no? This is more for pre-purchasing than maximizing speed/power through rev limiters and/or chips. Thanks.
jlindy-

I think the answer to your question would be "any" RPM over redline should be enough to ward you off. Just to re-cap, we were talking about three separate events, only two of which are problematic from a future warranty perspective:
1) banging into the rev-limiter on aggressive upshifts (this is the benign event, as the rev-limiter works as designed and prevents engine overspeed)
2) running increased redline due to 'chip' tuning: whether it's the root cause or not, this could present problems should you ever have engine internal failures and a record of operating beyond OE redline limits (see exchange above)
3) missing a downshift and going WAYYYYY into the red. A very bad thing....
 

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jlindy said:
I just wanted to get back to my question. How much is enough to set them off? If I find a vehicle that has some codes in it's computer, should I walk away from the vehicle because the warranty may be void or no? This is more for pre-purchasing than maximizing speed/power through rev limiters and/or chips. Thanks.
From the E46 M3 experience, my understanding is that what is recorded is the total time spent in excess of a preset rpm level (for M3 it was 7800rpm when redline was 8k) in addition to max rev level. Also this information was not able to be read by the dealer. They have to send the DME unit off to BMWNA to analyzed.

Here's a link where Jim Conforti reveals all:http://bimmer.roadfly.org/bmw/forums/e46m3/2412688-10.html
 
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