Please read this, especially if you know your GTs! I can't figure this out!
For a couple of weeks now, despite really smooth acceleration when I let off the throttle a bit it kicks back. Also, when cruising at about 80mph it feels a bit lumpy... dunno why.
I've also had a new rocker cover gasket recently, fitted by me, and as my tools are at my parents house I fitted this when the car was still a bit warm and topped up with oil when I'd finished. Consequently, on checking my oil level the other day I found that I'm about 4-5mm over the top end of the dipstick "max" level. I'm told it burns this off with time, so I'm leaving it to do so.
Anyway, last night I drove to Sheffield. When I filled up before I left Cardiff, I noticed that I'd used a lot of petrol up, about 10 litres in 55 miles. It's been very variable lately, I've had 36.5mpg, then 28mpg, then 32mpg and now this is mid 20s. It's been running fine, so I thought I'd change to my chipped ECU for the drive up in case the one I had been running was carrying some random error log.
Anyway, on the drive up I stopped off at Hopwood Park services to fill up with petrol again. I worked out my petrol consuption to be about 24mpg!!! Really heavy for a car that's now running its paper filter and airbox again, and that's motorway miles too!
Thing is, it was driving fine on the way up, really quick and smooth acceleration and most of the time it wasn't kicking back on deceleration though it does still seem to be doing so. I parked up and revved the engine hard, and a little black smoke and some flakes of carbon came out of the exhaust. No oil coming out of the exhaust, smooth idle and the exhaust fumes don't smell of petrol so I assume it's not running rich.
Drove the rest of the way to Sheffield, and my petrol guage is indicating a similar MPG figure to the first half of the journey. Also, it's still kicking back sometimes when I decelerate.
Is it the oil burning off? What's doing this? Any ideas?
If anyone near Sheffield has an idea and fancies having a look, would also be much appreciated and I don't mind paying someone to have work done on it. It's cost about £40 to get from Cardiff to Sheffield!
Thanks in advance,
Alex