Misfire at 5K

[davidn]

I'm getting a misfire at 5k, only happens when opening the throttle quickly and feels like a rev limiter but not if throttle opened gradually so isn't, also fuel consumption seems high, 100 miles from a tank and no it hasn't got a leak. Any thoughts?
David

[2 sheds]

When were the plugs last changed , are the leads the originals ? sometimes replacing service items like this can resolve a mis-fire.
Tim

[jigs]

This happened with my 4.3 precat Griffith some time ago. I replaced all the usual suspects, i.e. plugs, ht leads, plug insulators, dist cap and rotor, coil, etc. Mis-fire was still there so on a fellow PHer's suggestion I changed the hot wire air flow meter. Bingo - problem solved. Has run fine since.

>> Edited by jigs on Saturday 24th May 22:19

[43scotty]

HI Davidn , Try removing the air tube between the air filter and air flow meter then take the car out for a run . i had the same problem last year.

[davidn]

Thanks for the help you guys, so far I've replaced HT leads coil and air filter. Checked mesh filter in air flow meter - okay, checked for leaks in ducting to plenum - oaky, checked throttle butterfly for gunge - oaky and lastly checked vacuum advance tube, no leaks but have run with it and without, blocking plenum connection with a rubber cap and there is no difference in the way the car drives, would this point to a fault with the advance mechanism in the distributor?
On your suggestions I'm going to replace the plugs and run with the ducting removed from the air flow meter but is there any way for an airflow meter to be checked rather than just replaced, they sould expensive.
Thanks all.
David

[jigs]

Airflow meters aren't that hard to remove/refit - get one of your TVR club mates to swop meters to try.

[siwes]

Hi
almost certainly your problem is the coil amplifier , the small solid state item next to your coil , they start to break down when hot , it is an easy and inexpensive replacement. I suffered for over a year with mine and two services at Blackpool they found it on the second one . good luck and its not yuour aif flow meter
regards

[jigs]

I agree that it's not 'yuour aif flow meter' but it might be your air flow meter.