Hesitation and jerky performance - any ideas?

[KentishS2]

I wonder if anyone can help??

My S2 has not been running so well, it is jerky and hesitant to accelerate.

I checked the dizzy cap, rotor and leads and replaced the plugs, all appears to be OK there now. The fuel pump and filter have also been replaced.

The car also revved up high until the car came to a stop. I took it to the garage and they plugged it into their machine and told me one air flow meter was sh*gged! The garage also kindly phoned TVR to see if my plugs were correct and they weren't and replaced them for me with the correct ones. I had fitted plugs listed for a circa 1990 Granada 2.9i V6, it would appear they are different for some reason although the same as the ones I took out ....strange. I also searched e-bay and found an air flow meter and won it with a bid of £4.99 for a genuine brand new unit ....what a bargain (the post came to the same price as the part)!

Anyway, now that's fitted and the car has been back to garage to set up, it runs a lot better and seems a fair bit quicker but it still has the jerky hesitance it had previously. I wonder if this is down to the injectors? I did try a Halfords "miracle in a bottle" type fuel system cleaner and it did improve the problem for a while.

Any similar experiences, or ideas anyone?

[Roy C]

Sounds like it could be the old favorite - The Throttle Pot

[WildfireS3]

TP - No no toilet paper, but throttle pot.

[KentishS2]

Thanks guys, you're absolutely right but I forgot to say that I have also fitted a new idle control valve and TP a few months ago.

That's why I think that it may be injectors as I think I have checked most things but if anyone has any ideas I really appreciate any advice.

[Hoover33]

I had a similar problem....and it was traced to a leaking fuel regulator

[s1.5f]

Have similar problem. Got my injectors cleaned and flow checked at Austec, made a big difference but still very slight jerkiness and unburnt hydrocarbons in the exhaust been traced by Paul to a fault in the ECU firing the injectors at the wrong time (he thinks). I still have a spare set of injectors you can borrow if you want to send yours away and not be off-road.

Simon

[KentishS2]

Thanks Simon that is kind of you but it's not my everyday car so I don't mind too much if it's off the road for a week or two.

I think you are right about the injectors, I suspect they have done the full 110,000 miles since new and now need a professional clean. I will have them out soon and take to Lucas Service in Hastings as I know the Guy there (Ian Duncan) who is a perfectionist and knows loads about petrol and diesel injection systems.

I'll also check out the fuel regulator just in case, leave no stone unturned!

If I carry on spending like this there may soon be a nice dark blue S2 up for sale to pay off an overdraft!

Kevin

[hrjs]

I have been having the same problem, albeit only during warm up. Associated with the problem as a cloud of black smoke upon, and for a few minutes after, ignition. I am told that the car is "over-fuelling" i.e. that not all of the fuel is vaporising upon hitting the cylinder wall. This is because the injectors are old and dirty, and accordingly the fuel is not injected as a clean spray. As warm up progresses, the increased engine temperature makes vaporisation easier, so the nature and direction of the spray is less important. The problem can be solved by: (1) A cleaning fluid (cheapest option at about £15, but not always effective); (2) reconditioning of the injectors (an hour or so of labour, but only appropriate in cases where the injectors are still in reasonable condition); (3) replacement of the injectors (at £80 each, plus labour. To be avoided for obvious reasons.)