The 12 gauge shotgun backfire...POW!!!

[bigwheels]

My 1990 Corvette has been mechanically sound since ive bought it, that is until recently the pesky "service engine soon" light comes on while driving long distances and dissapears. The exhuast has always poped a little on deceleration, nothing alarming just normal sounding. Its has become much worse with huge backfires on deceleration from highways speeds, when you try to hold a steady speed the idle begins to hunt. i have changed the distributor cap and rotor, ignition control module, and the spark plug wires, and the spark plugs were changed 600 miles ago and were gapped accordingly. I dont belive its a vaccum leak, you cant hear one, and my car runs way too smooth for that; never stalls. My Corvette currently has 51,000 miles, no modifications have been made besides the exhaust which has gutted cats(all of them), and flowmaster catback force II mufflers. This was done about 800 miles ago. It could be lots of things, but im open to any ideas. Please help its Corvette season and im ready to drive!

 

[boomdriver]

fuel is too rich and the "mods" to the exhaust has lowered its ability to hold any kind of back pressure. These engines have a minimumcylinder back pressure. Remove that, its going to misbehave.

 

[FForward]

You need to pull the codes first......might be the 02 sensor

 

[bigwheels]

fuel is too rich and the "mods" to the exhaust has lowered its ability to hold any kind of back pressure. These engines have a minimumcylinder back pressure. Remove that, its going to misbehave.

Thanks for replying! I will definetly look into your suggesions about the exhaust and its back pressure, as well as the fuel mixture being to rich. I wonder why my corvette would start to backfire 6 months after the mods instead of right away. who knows....

 

[bigwheels]

Many thanks

You need to pull the codes first......might be the 02 sensor

Thanks man! Corvette owners are different from any other type of car owner because they have sympathy, and you have definetly displayed that.

 

[TedC]

A stock L98 engine is designed to operate with some exhaust back pressure. Zero back pressure can cause some interesting side effects. However, I think you have a rich mixture problem that is being caused by something other than your free flowing exhaust system. I would get a scanner and see what the ECM is seeing. The single O2 sensor can only monitor the driver's side.