backfire HELP!!

[black97awd]

i have a 97 tsi awd auto i replaced wires plugs and o2 sensor and put a 3"downpipe and 3"catback and now when im at a stop then floor the car it goes then around 4000-5000 rpms it backfires once or if im just driveing then floor it it will backfire once then drive normal does anyone no what could cause this or how to fix it thanks

 

[chico904]

Could be a boost leak, possibly vacuum leak, as well as plugs. What plugs did you get, and what did you gap them at?

 

[Backinajiffy12]

did you take out your cat?

 

[throwedgsx]

boost leak. Do a boost leak test

 

[black97awd]

i dont have a cat and i put ngk plugs in it

 

[throwedgsx]

What model ngk's? What did you gap them at

 

[black97awd]

i dont remember the model i gaped them at .29

 

[throwedgsx]

bpr7es ring a bell?

 

[black97awd]

yep thats what they are

 

[throwedgsx]

I don't know what to tell you then. Maybe try closing the gap on your plugs a little more. Does it backfire everytime?

 

[black97awd]

no not everytime almost everytime tho like 6 out of 8 times it does it

 

[throwedgsx]

Is your car running really rich?

 

[black97awd]

i think so it puts out a lil black smoke thats why i got a new o2 sensor but it still must be running rich and i dont no why

 

[throwedgsx]

Did it ever do it before you replaced the plugs, wires, and 02?

 

[JMiller]

I had a simular issue but the back fire turned into a misfire in cylinder 3. The problem was my plugs were gapped to much. But if you didnt have the issue before i would say re check everything you installed. If that doesnt fix then do a boost leak test.

 

[black97awd]

no i noticed it about a week after i put the 3"downpipe and exhaust

 

[throwedgsx]

I would make sure your plugs are still gapped correctly.

 

[black97awd]

alright thanks for your help

 

[chico904]

i dont remember the model i gaped them at .29

Dont know if it will make a difference, but it should be .28

 

[chico904]

Also with your mods, you should be running BPR6es

 

[Backinajiffy12]

Reasons for back fireing
http://www.dsmtuners.com/forums/newbie-forum/306076-exhaust-pops-flame-cat-no-cat.html