Backfire at WOT When Cold

[rico05]

WTF. Never did that before I put the dp on. Any thoughts? My cold start really really sucks. Anyone think a new O2 sensor is in order (even though its heated)?

Cleaned AAC, set timing, no vac or IC leaks, cleaned MAF, no ECU codes, new NGK plugs w/ proper gap.

[WeldingHank]

when the engine and O2 sensor is cold, the ECU runs you rich just to make sure the engine isn't going to lean out. if the O2 is old, i would change it anyways.

[rico05]

How long should it take to warm up? I think it is the O2 sensor because after a hard run through the gears (ie more exhaust gas than at idle/low revvs) it goes away and I can boost/accelerate smoothly as much as I want.

[WeldingHank]

yeah, after you drive hard the O2 sensor is nice and warm. just don't beat your car when the engine hasn't warmed. its not really a good idea anyways.

[rico05]

I don't boost on it at all untill it is all the way warm and I never boost under 3k RPM anyway.

[WeldingHank]

are you running a BOV or a by-pass?

[rico05]

None. Stock IC and piping.

[Notchbackca]

don't go WOT when cold first off

and secondly its not a backfire, which can do alot of damage, its excess fuel being dumped into the exhaust system and as soon as the super hot fuel hits oxygen it ignites, causing the pop

[Xero]

YES it's the O2!!!

I just replied in yoru first post, my car was running super DUPER rich, my O2 sensor exploded!!

it would pop like a backfire whenever I let off the gas, but nothing came out thanks to my prolly burnt out cat.

I'm willing to bet it's the damn O2 sensor, they're not that much, go to the parts store!!

[paul_s13]

ecu temp sender?

[xTearsFallForeverx]

i have a stock ka24e that i just put a short ram intake on. its doing the same thing. ****ty start up till the engine gets warm. 3-4 min after it warms up it runs like a beast.. but crackles and pops when i let off gas. then when everything gets all hot.. car acceleration gets real poopy. engine been running way too rich for a long time. when i punch it i get a nice blast of carbon out the exhast. not oil.. carbon its black smoke. o2 sensor? thought it was the MAF but it seems to be working fine cause when i take off the plug it dies. unless its just malfunctioning.. but not sure what the error code for MAF is.

[rico05]

No offense man, but trying to compare KA and CA problems is hit or miss at best.

I replaced the O2 sensor and the water temp sensor. And no, the O2 sensor is not cheap. $63 @ NAPA.

[xTearsFallForeverx]

nvm guys i found someone with same problem as me. did the same thing i did. I have my answer is the idle control valve. hose not hooked up