1994 H/c/i Cobra Backfiring

haulbalz

Founding Member
Apr 6, 2002
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I'm Having Some Issues With My Mustang, It Seems To Be Backfiring Through The Intake When I Shift And Let Off The Gas. Plus When I Get It To A Certain Throttle Spot It Jerks Back And Forth. I Don't Really Know What It Could Be Because I Just Got It Tuned And It Ran Fine, A Week Later It Started Doing This. The Only Thing That's Not New Are My 24# Injectors, Fuel Pump And Tps Sensor.. Everything Else Has Been Replaced. Could It Be One Of These? Your Help Is Appreciated.
 
Back fire through the top is usually an indication that spark is way off.

You see this lots of times when the dizzy is way off like after it has been reinstalled.

It is possible that the guy that did your tune up left the dizzy hold down bolt loose causing the change.

Later
Grady