long story short i have a 408 in my 2000 ss that has backfired a total of three time in the past month. all three times car was being driven in town, and has happened when after i stopped at a stop sign and then kind of got on it. my tuner says its not a tuning issue and has to be machenical problem. wondering if anyone has had this problem? whether its a spark plug, timing, fuel, tuning or injector problem i just want it fixed and hoping someone else has been in my shoes.

 

Last time I had an engine backfire on me it was because I had used the wrong intake manifold gaskets and it had a vacuum leak at the port between the head and intake. This was a gen 1 engine not a Gen 3+ but I would expect a similar result if a port seal got rolled out of it's groove or something during install.

 

it also seems to run a little on the rick side at idle

 

If one cylinder is sucking air at the port the O2s will "see" that lean lean condition once it is mixed with the other 3 cylinders on that bank and dump fuel to compensate making the other 3 rich.

Have to remember fueling correction is done bank to bank.

I thought of another case where I had some backfiring, it was a single dead injector on an LT1. One injector was just dripping.

 

the more i get into it the more its looking like a fuel problem

 

i know something is wrong when it backfires and blows an muffler off

 

i blew 2 off one night but that was a wide plug gap and a lil too much n2o.

 

If the fuel mixture is too lean (not enough fuel) you may have a backfire in the intake, have you checked you air to fuel ratio?

 

Some data logging may do wonders for determining wtf is going on..............