Trouble Running On Idle & Running Rich

[giblet]

Evening chaps. Slight issue with my car, both yesterday and today the car was struggling on start up after having being parked up overnight. It started and cut out yesterday and today it was close to doing the same. It also seems to be running much richer if the smell of unburnt fuel is anything to go by.

Looking at fuel usage it has dropped by 7mpg between the last two tanks. First tank was the motorway miles to Mr Mann's place and back with some WOT thrown in at times. Second tank was Leeds to the Lake District with a bit more WOT this time but still a fairly similar driving style.

Could the lambda sensor be on its way out? Its the only thing that has been touched in between tanks that I can think of that could be causing the issue.

[Nick Mann]

It could be. Remember the plug behind the interior panel? Check that is still plugged in. Also check for boost leaks - a leak could be causing poor running. If the down pipes have sprung a leak or didn't seal properly that could cause minor issues too. The only other thing we did that comes to mind now is if one of the HT leads is not quite seated properly. Is it running smoothly on idle or lumpy?

[exevoowner]

Do a ecu reset

[giblet]

Fired her up today, started fine but she seems ever so slightly lumpy on idle. Still seems to be running rich as the smell of unburnt fuel is stronger than it used to be. Weather has been terrible and is forecast to be just as bad for the next few days so won't be able to check the plugs and leads for a few days.

[Nick Mann]

I've seen magnecor leads not sit properly on the rear plugs. You could hear the spark ticking on idle. The tick is much crisper and a bit higher than a lifter tick. I've also seen a plug that wasn't seated properly cause a lead to lift off the plug with similar effects. I can't comment on mpg as the owners didn't mention it, but both cars were a bit down on power and were running lumpy on idle. If the downpipes were leaking or the lambda sensor was ropey you should still have a smooth idle. A boost leak could make the idle lumpy though.

[giblet]

I think you might be spot on with the leads diagnosis as I do remember hearing a louder more pronounced tick compared to before with the lifters. Dry weather forecast for Friday so I will try to sort it then. Looks like it's the K11 for a few days, will help the wallet after 3 tanks of V Power in 4 days.

[Nick Mann]

If it is the lead that is the problem, then I have to apologise. I normally mention to people that magnecors sometimes need a good shove to pop on properly. I guess I was distracted when you got to that bit and never mentioned it.

[giblet]

No worries, I was being overly cautious when fitting the plugs I think.