Question on boost/vacuum meter

on 5.0 1992 mustang I have a boost/vacuum meter
has a KB 6 pound on it
has been running for 10 years this way OK except when really hot outside(100
or more) then some det. and I back off

When cold, sometimes the meter vacuum (-20 to -10 or so) and then it will
spike into boost a few psi and then back down very quickly 1/4 second or so.
I think the engine may be backfiring.
then when it goes closed loop, it doesn't do it much anymore.

Any other possibilities or ideas on how to fix ?

greg wrote:
> on 5.0 1992 mustang I have a boost/vacuum meter
> has a KB 6 pound on it
> has been running for 10 years this way OK except when really hot outside(100
> or more) then some det. and I back off
>
> When cold, sometimes the meter vacuum (-20 to -10 or so) and then it will
> spike into boost a few psi and then back down very quickly 1/4 second or so.
> I think the engine may be backfiring.
> then when it goes closed loop, it doesn't do it much anymore.
>
> Any other possibilities or ideas on how to fix ?

My advice is to get a chip with a tune for having the blower installed.
You symptoms could be caused by numerous things and it is nearly
impossible to diagnose the problem with limited information. Most
issues are tuning related, then fuel delivery followed by the ignition.