[Babes]

Has anyone had their engine cut out due to too much boost? Just had a call from the unichip dealer fitting new chip and they say it keeps dying at 3000rpm at WOT. He thinks its a boost cut off as its running 17psi which is quite high apparently. If you go through rev range not quite WOT it sails through smoothly but WOT it cuts out again.

Does anyone know if it is a boost cut off, never heard of that before on the MINI? They have them on skylines and wrx's im told.

[roland2003]

Hi jason, no we ran upto 20psi with the SC and have hit 25ish with the turbo.
Best Regards Roland GTT

[Babes]

thx for that roland, any idea what would cause it too cut out like that then?

[Richard Crofts]

Dodgy sensor somewhere making the ECU think theres a problem?

I know folks hitting over 17psi on road cars regular ... some GTT some others

My suspision is its not actually boost related its a fault with something on the cars electrics (either fuel, rpm, boost ete etc sensor gone wild or something else)

[Babes]

ok seems it could be the plugs causing the probs!

[Richard Crofts]

Strange. Plugs you'd expect a misfire not total engine failure. Is the car just loosing power dramatically at 3k rpm, missfiring and so going t hell at 3k rpm, or is it actually conking out totally?

Misfire would suggest issues on fueling or spark (either plugs or leads/associated cables).

Dramatic loss of power but not missfire suggests ECU issues (sensors causing EML to come on, limp home mode etc etc maybe correctly due to an issue elswhere on fueling etc, or maybe due toa faulty sensor on manifold etc)

Total stop would suggest something similar where the car is struggling even more to adjust for issues and so it fails totally.

[Ant FR]

I assume we are talking about the supercharged MCS, if it had been Turbo i would have said MAF triggering safe mode. Does the SC version run a MAF sensor??

[Babes]

basically it is a stumble at 3000 at WOT, if you drive nicely is sails through no problem and then 50% of the time WOT it sails through just the other 50% it stumbles briefly before reving away. It didnt do it before fitting screamin deamon ignition and nology hotwires so im guessing it has to do with spark.

car goes into bmw tomorrow for a few other things and will get them to check fault codes as SES light came on.

just read on NAM a few others with the same problem

[Richard Crofts]

Also maybe ask them to reflash the maps with latst software...this solved a lot of fueling and DSC issues that I had (best £30 I spent in the first year of owning it)

[Lucky Dave]

it maybe to modified map? what did the old one do? im seeing 19.5 psi boost with no problems!

[Babes]

it was there before with the MTH map, was hoping a custom unichip would get rid of it but has made it more apparent. We will see what codes it throws at BMW today

The car is still perfectly drivable, like i say its only sometimes at WOT.

[Capsaisin]

Quote: Originally Posted by Babes (original)

basically it is a stumble at 3000 at WOT, if you drive nicely is sails through no problem and then 50% of the time WOT it sails through just the other 50% it stumbles briefly before reving away. It didnt do it before fitting screamin deamon ignition and nology hotwires so im guessing it has to do with spark.

car goes into bmw tomorrow for a few other things and will get them to check fault codes as SES light came on.

just read on NAM a few others with the same problem

Can't you put back your old coil and wires and see what happens?

[Babes]

forgot at the same time i changed wires and ignition i also removed the flap on the rear of the JCW airbox. BMW seem to think this might be the cause so will take the flap back tomorrow for refitting and see if that sorts it.

[roland2003]

Did the Unichip dealer give you an AFR graph. ?Just wondered if youve maybe got a nasty little dip leaning it off at 3000rpm?. If not connect up a wideband and do a couple of WOT runs in say 3rd or forth to see what your getting.

[Richard Crofts]

Get some big injectors and a variable FPR from Roland... that'll soon solve any leaning out

I think rolands right a wide band AF sesor while testing on a RR or the open road will probably give you some interesting results. Can't see the flap on the airbox being an issue...if anything I'd say it being fitted and reducing flow then suddenly opening it to flow would be more likely to cause an issue than it being open all the time??!

[Babes]

Went in today with the flap to replace and BMW could not get it to stumble at 3000. I took it for a drive and it seems to have gone! No idea what was going on but whatever was happening has stopped and it runs smooth right through the rev range. Im a happy camper especially with the 20whp extra the custom unichip gave.

[roland2003]

..Maybe when the flap was removed the vacuum pipe that operates was disconnected. If its not either connected or blanked off, the bypass valve doesnt see vacuum and therefore doesnt open properly. This can give symptoms like you describe.