exhaust pop/slight backfire type sound on 30%+ acceleration

[stratt134]

stock 2g turbo, SSAC FMIC... decided to cut the stock exhaust behind the cat/rear o2...

Since then, the car would pop or backfire under 60%+ TP acceleration.... a few times in each gear on full pulls. Not 100% of the time though...

Then i swapped out what was left of my stock exhaust for a Megan Racing downpipe... eliminated the cat, kept rear o2...

NOW the car pop/backfires 100% of the time on all 30%+ throttle position accelerations or pulls... 3-4 times per gear/shift..

Anyone have any ideas why? Was thinking a back pressure issue... but I have a friend who did the same thing and his car didn't do this...

Is it leaning out or something? Car thru a P0170 fuel trim malfunction code recently... BUT that was before I cut the exhaust or put the downpipe on. Maybe bad o2 sensor or something? I noticed the #1 o2 sensor on the o2 housing was solid white/light gray... the rear o2 was black as normal... does that mean anything as well? (I haven't had a chance to check the voltage going to the #1 o2 to see if it is bad... but...

DSMLink v3 & GT35R coming very soon =)

Again, all help is greatly appreciated!

 

[boostedinthe843]

kinda sounds like your plugs are going out, my buddys car would breakup/pop under a load. i would say pull your plugs and check them, your not throwing a CEL are you

 

[stratt134]

throws p0170 fuel trim malfunction.... maybe bad o2 or plugs.... will check the plugs tomorrow...

 

[KeelesKustome]

i agree it sounds like since you removed the backpressure equation that it over compinsated with fule fludding out, your plugs, screwing them over.

as another previnitive measure, why don't you move your o2 sensor.


as for getting rid of it... I am not sure, but i know with my dsmlink, that i highly rely on my o2 readings for my tuning process.

 

[stratt134]

less back pressure/extra fuel.... are people running different tunes for open downpipes??