Hi - Twice now in three weeks the car has shown the reduced engine performance after foot to the floor acceleration but not straight away (second time it happened was after two runs foot to the floor).

I have been reading around on the subject and it appears there are four possible common causes:

1. MAF sensor - but this seems to come with misfires and stalling etc and error codes logged

2. Throttle position sensor - again comes with error codes

3. Wiring for SC aux coolant pump wrong from factory - dealer has checked and confirm correct

4. SC aux coolant pump is failing - seems most likely cause as others have had this and no codes logged and would make sense of why it only happens when car is pushed really hard

Does my deduction of the possible causes make sense and would having the coolant pump for SC changed make sense?

Thanks

Simon

Coolant pump wiring was my first thought, but as you’ve had that checked . . .
Not sure how you check the pump itself but from what I can remember reading it’s not too difficult a job for a DIY to change and the pump itself is (or was) about £120. 2006MY 4.2 SC
BMW R1250 GSA Rallye TE
Triumph Tiger 1050 (sold)
1979 Pontiac Trans Am (sold)

It's going to be your supercharger pump.

Irrespective of what the dealer says, I'd check the wiring to the SC pump - I'm not sure any were wired correctly.

If you can get access to diagnostics such as an IIDTool, check the SC output air temperature. After 5 WOT accelerations up to speeds above what be legal in the UK it shouldn't get anywhere above 60°C (with ambient at 20). With an unserviceable pump it will rapidly climb above 90 and you'll get the reduced engine performance error as it passes 105.

I know this because that's how I diagnosed mine - it was wired backwards and even when wired correctly was obviously running slowly (and making a pretty nasty noise). With a new pump fitted I can't get it to go above 60°C no matter what I try.

Hope this helps!

Yes, agreed with Mulcher. It is a relatively easy job to do SC pump inspection) though a bit fiddly. Pull the front cover off the volute housing and power it up from the car plug and confirm correct rotation direction.

This will prove three things. It will confirm you actually have power arriving from the car plug to the pump when the key is on (check plug pins with multi-meter if no pump action), it will prove the pump motor is working and it will confirm the polarity is correct and hence the direction of rotation is correct. Conversely, if the car plug does not power it up, there is some other electrical issue there to explore.

It's the only way to be 100% sure. Put the volute cover back on and away you go. It was a cheap pump too, available on eBay or otters sources form memory when I did this some years back.

Regards

PC. '07 4.2 S/C
'13 X3M

My aux coolant pump was also wired the wrong way and my VIN is way after the era when this was meant to be sorted at the factory and as everyone else has said this screams failed pump from your symptoms. 2008 MY Supercharged
Rimini Red / Jet
four zone climate
remote park heater
and no ugly kid windows.
magnus satis quod turpis satis

Thanks for replies glad to hear all the reading of all old posts was worth it.

Its booked in now for coolant pump replacement I just need to work out how to check the wiring myself now beforehand.

Hi,
I had the same issue for one month when crusing at 80 km/h pulling a 3 tons trailer. The first 3 hours of travel were problemless on the belgian motorway, then I reached a long steeply slope (approx. 3 km) when suddenly in the middle of it the message "reduced engine performance" appeared. I was obliged to reduce speed at 70 km/h and stopped at the first parking area. I connected the ID-Tool but coudn't read any errors linked to the problem. After a 15 min stop I pushed along, the engine responded well to the right foot, no issue again during the 3 last hours of driving.
I wondering what could have caused the car to reduce performance, as I was trailling quite hard, could the gearbox have overheated and if so could it be the reason why I got the message?
Note : the gearbox is running fine otherwise, I changed the oil and filter 10000 km before (at 200 000 km) Current:
- L322 2006 S/C lpg
- RRC 1988 lpg / 287 000 miles
- Stage one 1981
- Lightweight 1976
- 109 SW 1968 under rebuilt

Gone: none

From what I have read of the REP message and no error codes people had it when engine was worked and supercharger was getting hot due to the failing pump or wiring issue.

As mentioned above diag tool to monitor SC temp will confirm if the aux coolant pump on SC is the issue

Quick update - car had the supercharger aux coolant pump and the wiring changed as it was damaged, car now seems to be fine after driving it hard and cannot get the REP message to re-appear.

Total cost including wiring, pump and labour at main dealer was £330.

I changed the pump on mine after having the same symptoms. I tested the pump I removed and it was intermittent, sometimes it would start and sometimes not. When it started it ran as normal. The wiring had been changed, but probably not the pump. It was easy to change the pump when you have this tool:

https://www.biltema.no/bil---mc/bilverktoy...2000018955 2006 Supercharged