Is this the cylinders misfiring while downshifting? How do I fix running rich. I have reset ecu 2 times.

 

No, it's not in the combustion chambers...it is unignited raw fuel in the exhaust getting "spent' in the piping. Happens alot when you start adding exhaust-type mods to any vehicle.

 

IS350 here. No backfire problem from the FSport exhaust.

 

Had it installed for a year now lol. I think its cause my battery got reset when the battery died, so I guess everything got reset.

 

I have same issue and code running rich. I has put in new MAF Sensor and Seaform fuel injector cleaner in gas tank. Car seem to run ok still bogging. But no check engine light. From CL member recommendation I also order 2 new Aire Fuel Ratio Sensor.

 

I had 3 code PO172, PO175 Bank 1 Bank 2 system too rich and bad MAF sensor.

 

Have you checked your mid-pipe for exhaust leaks, especially under the heat shield? When it happened to mine, one of the symptoms, besides sporadic P0420 DTCs, was occasional backfires during deceleration.

 

I get the occasional backfire when the car is a bit colder and I accelerate out of the parking lot and then let off the gas. No big deal.

 

Same! I love it lol If I gas it and let off, the exhaust will gurgle and back fire as the car downshifts. It also does is when I'm slowing down after driving hard. I don't have the F-Sport exhaust though. I got the resonator and mufflers removed.

 

Nope, haven't check I have no CEL and no VSC lights. I only notice it when its a pretty hard brake. If its slowly decelerate it doesn't backfire but I'm worried running rich might cause some problems.

 

I always backfired with my f-sport. Like you described and especially right before coming to a stop. I put over 45000kms on it with no issues. Vancouver driven also if it makes you feel better .