Loss of power under load

[Steve Brown]

Sun was shining this afternoon, so thought I'd give the seven a run. Not been out of the garage for a couple of months, so gentle warm through until water and oil up to temp - no problems. After about 15 miles, everything up to temp and cruising on dual carriageway at around 5000 revs (1.8k supersport, 6 speed) when start to lose power. Pull into layby and it idles slightly roughly but is happy to pull away, but under load it's not happy at all, misfiring badly. Crawl home, where it'll rev quite happily on the drive - so only misbehaves when asked to do some work. Any ideas?

[The Stig]

A long shot....It could be many other things...

Check the Cat is not rattling or it is not broken up and restricting the exhaust flow. I had this problem on Tintop 8.0.

 

Did she run at all warmer than normal?

[Steve Robinson]

Could be the problem I have had with my SL twice now. Harder you squeeze the throttle the more it loses power and sounds like a tractor.

 

Check the spark plugs, I changed them for another set and the car runs perfectly.

 

Robbo

[robmar]

I wonder if somehow your ECU has gone into an emergency map

 

I was in Daren Balls car when we had very similar symptoms, I think it ended up being a dirty flywheel sensor or someother sensor, cleaned it up and allwas OK.

 

if yours is one of the older K series (I mean a non EU3) then try resetting it using the pumping of the accelerator 5 times with the engine off.

 

of course ICBTRIOA

 

rob

[Steve Brown]

It's a non cat (4-1 exhaust) car. I'll try the reset scam - please remind me of the routine. Thanks.

[robmar]

I think it goes something like this, but I am not 100% sure as I do not have one on my car

 

1. ignition on

2. immobilser off

3. pump accelerator 5 times,

4. fire it up

 

I am sure somebody else will give a more definitive answer

 

rob