Hello All,

I've got a 1989 S10 Blazer 4x4, 4.3L, auto, TBI, with approx. 175K
miles on it.
Last week, my wife, on her way to work, ran over a rock. Since then,
the engine has developed a miss. I'm not saying the cause of the miss
was hitting a rock, but I thought it might be relevant. The miss is
especially noticeable under a load.
I have tested the coil and distributor pickup, both are OK. The vacuum
tube where the PVC valve attaches to the bottom ot the TBI was clog.
Cleaned that and now have vacuum there. Replaced the PVC valve and air
cleaner just because it was time. This week I'll replace the plugs, and
throw a bottle of Techron in the tank. Nothing so far has eliminated
the miss.
I need help with this. What is the next thing(s) I should be checking?
EGR? IAC? Would LOW back pressure cause this? (I found the muffler was
loose where it attaches to the cat.)
Any help appreciated and welcome. TIA

Leyton at Tahoe

L8ndeb wrote:
> Hello All,
>
> I've got a 1989 S10 Blazer 4x4, 4.3L, auto, TBI, with approx. 175K
> miles on it.
> Last week, my wife, on her way to work, ran over a rock. Since then,
> the engine has developed a miss. I'm not saying the cause of the miss
> was hitting a rock, but I thought it might be relevant. The miss is
> especially noticeable under a load.
> I have tested the coil and distributor pickup, both are OK. The
vacuum
> tube where the PVC valve attaches to the bottom ot the TBI was clog.
> Cleaned that and now have vacuum there. Replaced the PVC valve and
air
> cleaner just because it was time. This week I'll replace the plugs,
and
> throw a bottle of Techron in the tank. Nothing so far has eliminated
> the miss.
> I need help with this. What is the next thing(s) I should be
checking?
> EGR? IAC? Would LOW back pressure cause this? (I found the muffler
was
> loose where it attaches to the cat.)
> Any help appreciated and welcome. TIA
>
> Leyton at Tahoe

BTW, there is no "service engine soon" light on.