Intermittent power at higher revs

[John.Reddie]

Well, my CSK has developed a strange behaviour... and I figured out that I probably had two issues, not one. Replacing the control unit on my LPG system has cured most of the trouble but I'm still left with "funny" performance on petrol, which isn't replicated when running on gas. (Thankfully, as I regard petrol as a last resort these days!)

So, up to around 2500 rpm everything is fine, but above that it exhibits symptoms that could be fuel starvation, there's sort of pull there but it cuts up and down, not in and out - it's more subtle than that, but one minute she's pulling like she should and the next not. Very disconcerting, especially if overtaking!

I've had this into two garages now both of whom assure me all is well and blame the LPG system for this. But I'm not convinced. The LPG problem was quite different, and at lower revs, and one could make it better or worse by bashing the old control unit. So their diagnosis, unprompted, of a duff controller made perfect sense.

I don't really see how a fault with the LPG system could affect running under petrol but maybe I'm missing something...

Anyone got any clever ideas?

thanks,
John

[John.Reddie]

OK, well whatever it was, it got worse, and then, about a week ago, it just suddenly went all OK again. I am mystified. Both LPG and petrol are fine, I've done about 500 miles since now in various journeys including several sustained hours on motorways etc. and it's absolutely fine... Weird.

I poked around and inspected everything I could get at during the time it was rough, and nothing I did made the slightest difference. Then one morning it just fires up and as soon as I pulled away I thought "this is better", got out to some open road, floored it and grinned!!!

One of the joys of running an 18yr old I guess...

John