Gulf Racing 310R
I've not heard of that before.
Presumably they're talking about engine vibration, if it was vibration from the chassis or road it wouldn't be at the same revs all the time, and it's hard to be see where enough vibration could come from the engine to do that.
If that's what they say, they should know, but I'd want a full explanation of that, which might be of interest to Sigma owners on here.
There is a thread - IMMOBILISERS AND MISFIRES - CONNECTED ? from 2003!
Turned out to be a broken PCB.
Since I'm currently having issues with my immobiliser (though it's a bit late now, since I've handed the problem off to Caterham), but just for better knowledge going forwards, does anyone know where roughly this relay hides under the scuttle?.
Update - it seems apparently the relay(s) are contained within the immobiliser unit as a whole
Mine is a Duratec but I had exactly the same symptoms you describe - a misfire high up the rev range.
I changed all the usual suspects, plugs, coil packs etc but still the same.
My dealer couldn't diagnose it and said it was likely to be the imobiliser which they then modified.
Still no joy. Took it to Northampton Motorsport who put tested it on the dyno and it proved to be a failing throttle position sensor.
TPS could have been an issue too - see below.
I finally picked up the car from Williams today - I had to wait for a new windscreen and roll bar to be fitted (also under warranty) at the same time...
I gave it a good few tests on the way home, and I can confirm that the hesitation isn't there anymore - it accelerates smoothly all the way to the shift light now
Apparently the TPS settings were all out too, so they've been reset to the factory settings. That's made a big improvement to driveability, so I can only assume the TPS settings were wrong when the car left the factory.
That's good news!
I'd love to know how much time/money Caterham spend having to fix stuff "under warranty" judging by what I read on BC and my own experience.
That`s probably why they cost so much in the first place!