RRS S/C: Help – Reduced Engine Performance
Driving over to France last week at about 85/90 and suddenly had significant loss of power accompanied by:
- orange engine management light coming on; and
- digital readout stating “Reduced Engine Performance”
Could still drive at 65 – 75 mph but very reduced power and no kickdown to accelerate.
Stopped in petrol station for 20 mins and fault had re-set with usual performance. Lasted another hour’s worth of driving before same thing occurred. Re-set after short stop and had another hour’s driving before the same thing occurred. Fault then remained all the way to destination. Orange light still on dash after a day’s rest.

Same thing had occurred once last summer and once earlier this year after very spirited drives but had re-set after short pause. Indie mechanic and I thought was linked to radiator issue (small leak) which was replaced and problem had not re-appeared until now.

Car is now with LR Chambery who tell me their diagnostics say a cylinder is out and are going to replace spark plugs and perhaps coil on Tuesday. BUT, except for the reduced power (which seemed to be an electronic control measure), the engine seemed to be running fine.

ALSO, I see from google that 2006 S/Cs can suffer from problems with supercharger cooling fans being mis-wired or failing after about 60k miles – mine has 70 k miles. There is a TSB out on the issue.

An overheating supercharger seems a more likely cause of my present problem than a sparkplug or coil issue.

Does anyone have experience or advice on this issue? In particular:
- would I be able to tell whether one cylinder was mis-firing/not firing at idle (I would have expected “yes”)
- could the problem with a sparkplug arise only at high speeds? High temperatures?
- If there had been a problem with the cooling fan, would the diagnostic equipment have identified it?
- In short, can I trust the LR dealer?

Many thanks for any/all help.

Michael

Quote:

- would I be able to tell whether one cylinder was mis-firing/not firing at idle?

Quote:

- could the problem with a sparkplug arise only at high speeds? High temperatures?

I think you will find it is the s/c coolant pump not the fan that was wired incorrectly, the tsb does say a possible symptom is reduced engine performance and engine misfire, if I remember right.

Cheers
Col

Was this really originally posted back in 2012? 2011 RRS HSE Luxury 3.0 TDV6 Fuji White on Ebony/Ivory
Born and raised in So Cal. Moved to the UK in 2018 for a few years. Now in Poland and looking at moving back to the UK.

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NoExpert wrote:

Was this really originally posted back in 2012?

Yeah, strange showed up as a new post for some reason, never even looked at the date.

Cheers
Col