Avo turbo backifring
 

I have an all catless exhaust with an avo turbo stg 1 and usually while on 1st gear cruising slowly up to 4k rpm to switch to 2nd gear I hear a really loud pop after I pop it into 2nd. Is this normal?? Doesn't a backfire usually indicate a misfire?

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Do you have a Vent to A BOV? Could just be afterburn.

Are you on base tune?

And you are running straight pipes so some backfire is to be expected?

Mine pops all the time. Base tune is running really rich.

Are you guys running the BOV and vented to ATM? If so, everytime the BOV acts, it will go pig rich, unmetered air is being lost.

Need a tune for that. Some people love the backfire though....

The backfire is controllable. Nothing wrong.

This is probably it. STI's, WRX's and other turbo Subaru's experience the same issues when a vent to atmosphere BOV are fitted.

IIRC, all the air that the computer has already calculated is gone due to the BOV, so its just fuel and very little air, resulting in backfire (correct me if I'm wrong here)

Yea, the BOV location os post MAF so that is why. A kit with BOV before MAF cannot produce backfires that easy :D

I had the AVO kit with BOV and basemap and misfires. What Pete says is correct, it was nothing crazy or too worrisome. When I got dyno tuned, it all went away.

Sadly you don't shoot as much cool flames now


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Yea, I'm bummed :(

I guess 500 whp will have to do for now...

David, when you had your avo kit I in your car, did it kind of thump as soon as you turned on the ignition?

"Thump" is a very vague....

Describe the thump