Just got the Z4MR from an oil and brake fluid change. I was parking in an underground garage and wanted to rev up the engine to hear the great acoustic from the sports cans in the rear, but to my surprise the revs would not go above 6k rpm (no matter how long you keep your foot on the accelerator). Is this normal (some protection activates when revving in neutral) or there's something wrong??
Engine Revs up to 6000 RPM only
- Thread starter danny_acs
- Start date
ive never tried it nor would i really want to, to be honest as its not to kind to your motor, but you are correct the engine will only rev to 6k in neutral, you car is protecting the engine from high engine speeds with no airflow ;-) i believe it will do the full revs with the clutch dipped and in gear.
danny_acs said:
Probably in my top ten best ways to wreck an engine - taking it unloaded to the rev limiter. Great job BMW do in protecting the engine
Liverpool
Ah one of my favourites. Combining a misfire and revving the engine to clear the problem. Might have worked on an old coked up 50's/60's sports car, but a big nooooo these days.
Unfortunately it required the Z having emergency medical treatment :thumbsdown:llamedos said:mmm-five said:Yet that's exactly what the BMW technician who came to look at my yellow light did for 30 minutes when trying to 'clear the misfire'
He would of only done it once to my car !
To suggest doing again would require him having medical attention !!!
survivalist
Member
Apologies in advance for my ignorance, but why is revving an engine under no load a bad idea? I only ask because I once went on a factory tour for a large car manufacturer and this is exactly what was done once the assembly process was completed?
S
S
survivalist said:
Survivalist
I don't believe that simply 'revving' an engine to it's limit will do that much damage per se. Of course an engine is designed to be run under load and without can be subject to excess vibration and stress Clutch, gearbox and drivetrain all damp the system. Poor analogy, but try peddling a bike fast without it's chain on and see how horrible it is.
For me the biggest damage is that this type of thing is usually done in combination with other things:
Over revving - simply as the engine can spin up so quickly it can go above it's limit and beyond it's mechanical tolerances. Easy to break things (hence BMW limiter)
Revving itself implies on and off to the limit as opposed to a progressive throtttle increase to peak and back down - unburnt fuel - ends in the cat burning, exploding and causing damage. fule washing the bores, etc. as the throttle is lifted quickly.
Cold - often done at start up when mechanical parts are not up to working temperature causing horrible wear and tear. Even in a car park the engine will have cooled internally and not expect the shock of hitting high revs instantly - very different to taking it up to peak over a second or so in gear.
Fault diagnosis - as noted above, to perhaps clear plugs, misfires, etc. resulting in high spinning ill performing engine. This can easliy cause a catastrophic failure as the engine is out of balance , damaged part stressed to listen to noises, etc.
So just my thoughts and why I'd never rev an engine and those who want to listen to the wonderful exhaust note I have, join me and the ///M's in a Welsh tunnel or listen to Andy's clips :roll:
My 2p is that it is fine to free-rev.
BMW add lots of things in to protect the retards from themselves, and this is probably for that reason than some other reason.
I'm fairly certain there is some coding in the ECU to stop this engine from being run on a chassis dyno above a certain rpm range, without doing something funny with the throttle, ignition and DSC button, to enable it to rev up properly.
Consider that 90% of the loads, possibly more, at 6000rpm+, are inertial loads due to the rpm itself, than the 'load' on the engine from any work it is being asked to do. I don't think the presence of load or not is such a huge worry, especially since you could easily clutch in in 1st and rev to 8000rpm+ anyway.
Hmmm
Dave
BMW add lots of things in to protect the retards from themselves, and this is probably for that reason than some other reason.
I'm fairly certain there is some coding in the ECU to stop this engine from being run on a chassis dyno above a certain rpm range, without doing something funny with the throttle, ignition and DSC button, to enable it to rev up properly.
Consider that 90% of the loads, possibly more, at 6000rpm+, are inertial loads due to the rpm itself, than the 'load' on the engine from any work it is being asked to do. I don't think the presence of load or not is such a huge worry, especially since you could easily clutch in in 1st and rev to 8000rpm+ anyway.
Hmmm
Dave