jrotsaert

Looking for some ideas. After our last race at Spa we let our battery drain completely before we re-prepped the car. Yesterday we got to Donington to test for tomorrow's race and our rev limiter is kicking in at 8000 vs 8600 REVS. These 600 revs are obviously critical and we are miles off the pace.
We thought something might have happened in the Bosch 3.1 ECU so we got the factory to re-send us a map and flashed it back in. Turns out that this did not cure anything and we sill have the same problem. We thought it might be the flywheel inductive sensor so removed the gearbox and cleaned everything (we couldn't find a new one) but again, this doesn't help...
Any ideas?
JM

A.Wayne

The most obvious thing would be crank error re-counts causing the ECu to mis-read RPM kicking in the rev limitier , this should be obvious in your datalog , look for max revs...as an indication ..

jrotsaert

That we have already checked.... any other ideas?

A.Wayne

What is it showing for max revs?

You said you have re- flashed the ecu and still have the problem, did you unplug the ecu before re-flashing , i would try doing this then re flash Software ...

Check for cam sync signal .....

DId you re start car using a Battery booster/charger ?

jrotsaert

The ECU was taken to a place 100 miles away and put in a different RS to do the flashing. It showed no issues at all in terms of settings/faults/etc. The cam signal is only used once at start-up according to Porsche Motorsports so if that sensor fails you can't start the engine but if it starts it's never checked again until the next time you start. We always have a slave battery to start the car (unless it's after a spin ). What's your theory on this?

A.Wayne

If using a slave battery there should be no issues, if using a high voltage booster charge you could have damaged the ecu... check to see if this was done where it was re flashed

I would unplug the ecu and re flash again , if it still persist , change the crank sensor , The Bosch sensor has a pretty high voltage output at 8000+ , It could be causing the software ot shut down at 8000, is the engine popping @ 8000 or feels like it runs into a soft limiter ....

jrotsaert

slave battery it was. can't redo the ecu it was done and there's no chance to do it again... and there's no sensor anywhere in the UK - the race it tomorrow... We've checked the data again and again and it's a hard cut at 7,995 RPM. The only thing I haven't looked at yet is if or any reason the map on the dashboard was wrong - you know the 1,2,3 with 1 being quali, 2 regular and 3 safety car.
After that, I have no more ideas...

analogmike

Make sure your battery and alternator are working well while on track. Obvious but important!
good luck!

jrotsaert

Why would the alternator cause problems at 7,995 RPM? I don't get a low voltage alarm anyway...

A.Wayne

Change the sensor gap, open it and see if the rpm limit moves ......

jrotsaert

Did that too... it was supposed to be 1mm but when we pulled it it was 0.6 mm. We've put it back to spec and nothing happened... Tell me more
JM

A.Wayne

Pull it back more , see if the rpm limit moves , are you able to see the software ?

analogmike

I raced a sports racer last weekend that had enough voltage to run the ignition, but the instruments and computers were screwed up as the alternator was cutting out, and would not rev up to redline. I guess your car is a lot more sophisticated so it would tell you if the voltage was not high or steady enough.

Good luck!

jrotsaert

Will try that since I don't have a better idea... but it takes removing the box again... From an electrical perspective however I don't understand why that would matter at all. The sound brakes an Em field and there's either a signal or there isn't and I can't remember distance playing a meaningful effect in the equations... usually it's 1/r2 the factor in Em fields... Am I missing something?
Any other ideas?

jrotsaert

Thanks for the explanation. Yes, the software would tell me that very quickly