Its fluffing !

[samurikid]

Ok so I am back from Caterham , being told that it isnt fluffing at 5900 like it was, and to be fair it wasnt for the 2 hours it took to get back. However , attacking the B16something and heading in towards Norfolk, it started again. So far the plugs,leads,dizzy have all been replaced, it is a Suplight R , and above and below this point it is fine. Flying infact. But if you are on a dual carraigeway it is just where you dont want it. Question is , what on earth is it.....anyone else got any ideas. Is it time to change the ECU on it and upgrade, trouble is what does that cost (Racing BMW's is the priority walletwise) , or would it be something nice and simple?

[Fat Arnie]

OK, it almost certainly electrical, being cuased by a duff input on the ECU.
If you can find someone with Easimap (assuming your car runs an MBE ECU) hook up and turn on logging. Drive the car until the fualt condition occurs, then save the log and reveiw it. Look closely at all the sensor traces.

Failing the skills/availability I do think if it is a fault always at specfic RPM my first point of diag would be to change the crank sensor, and if poss check the pick up wheel is not loose on the crank.

[samurikid]

Cheers mate - good plan! Will see what I can find .....Easimap .....right .

[sam919]

When does it happen? i had a problem with the main HT lead arcing against the block at intermittant revs. It had been cable tied to the bell housing/ clutch bracket.Start the car and turn the lights out, check for sparks! sounds a bit half arsed but i saw it arc and was able to pin point it.

[samurikid]

It happens when it gets to abouot 5900 revs, any gear, on the straight or in a corner. And it seems to be only when it is under load,not when being revved at home........As far as I am aware it is standard as a standard thing under there so any ECU referance should be as the day it was brought into the world !

[dannylt]

You're lucky it happens consistently rather than intermittently - makes it a lot easier to find

[jeremyc]

Do you have a battery master switch?

If so, check it isn't this going faulty (simply bypass it); I had similar symptoms to you as the precursor to a complete misfire (and then nofire ). I also have an SLR ...

[Dave J]

coil duff

5900 is pretty close to max torque....

[bikemonster]

Dave J said:

coil duff

5900 is pretty close to max torque....

Bypass the coil and see if the problem goes away.

[Fat Arnie]

Having read this thread again, I'd also look to get your map refreshed. Or swap your ECU with another factory car of same engine spec.

[samurikid]

It was my initial thought to look to the ECU. On wednesday I shall go through all the other ideas you guys have had, and that will leave only one thing - back to the ECU! If it is that , and I end up looking at a replacement unit (eg upgrading) what does everybody recommend, and what would one spend ?

[Fat Arnie]

There will ne nothing wrong with the ECU, just a carelessly edited map perhaps.

Get the ECu refreshed, and check all the earth connections on the ECU plug are good connections to ground. Use a digi meter.

There is no affordable ECU any better than MBE.

[Fat Arnie]

Hang on, Superlight R????? Is it on the crappy modded Rover ECU?? If so, get a Supersport R kit - inlcudes all you need to gte the car from 190 to 210 bhp, and youy can probably sell the Rover set up for a grand!

[sam919]

If you think the ECU is out check the square waveform using a o'scope on idle and through the rev range, you should be able see any discrepancies.

[1st_petrolhead]

Bit obscure I know but check your cam belt is tight

[Fat Arnie]

Sam919, Kind of hard to attach a scope on any load site nigher than about 3 (of 15) Also you'd need to check the fueling drive as much as the ignition.

And a loose cambelt? I think you'd be in rather more serious trouble than a fluffy misfire!

[sam919]

Fat A, not if you have the right equipment, where do you think you would have difficulties

Edited by sam919 on Monday 4th February 16:58

[Fat Arnie]

Sam, do you have a rolling road then?

[sam919]

Yes i do but you don't need one

[Fat Arnie]

I'm intrugued as to how you would read an oscilloscope with the car moving?