Although , I generally think of ignition problems when somone talks about
"mis-firing", the fact that you can slow down and then speed up again for a
few minutes makes me think that you should check/replace your fuel filter.
Often a fuel filter that is partially clogged will allow enough fuel for low
rpm,
low power requirements, but will starve the engine when you put your foot down.
You can never do yourself any harm by replacing fuel filters (barring something
really bizarre ) and they are cheap unless you have fuel injection.
Jim S.
> Wow, it's the day for mystery problems just like mine! I have the same
>thing, but
> at ~73 mph (~4200 rpm), only in fourth and only after about 10 minutes
>driving that
> speed. It also seems to go away from time to time. Of course, I generally
>don't
> drive for ten minutes at 4200 except on the highway in fourth...
>
> The problem seems to be fuel-related in my case. If I slow down by 10 mph
>and
> drive for a few minutes, I can speed back up again for a while. Then it
>happens
> again a few minutes later.
>
> There are no strange noises. It's not suspension or brake related. I have
>pulled
> over and checked the coil - it's warm but not hot.
>
> I haven't yet pulled over and checked a plug. I have had multiple things
> contribute to this. I definitely had float and needle-valve problems at one
>time.
> I believe those are fixed. Vaccuum problems affect it too. I had a leak at
>the
> EGR connection between exhaust and intake manifolds. This made the problem
>occurr
> at lower speed.
>
> My belief is that with all this smog stuff on the car, a vaccuum leak has a
>much
> more profound effect on the mixture than it would on a less
> vaccuum-driven-wierdness-intensive vehicle.
>
> So check for vacuum leaks, and check your fuel system/float bowl.
>
> Do let me know if you figure this one out, cuz I've been trying to solve it
>for
> almost two years.
>
> -------------------------------------
> Alan Coleman (alanco@sybase.com)
> '79 Spitfire
> '64 TR4
> -------------------------------------
>
>
>
|