Back fire after cat, and new O2

[Scaramoche]

Hey all, update

 

I passed Emissions!

 

Now the problem lol, seems im full of them.

 

I got a new cat, and o2 sensor, but now im having backfire issues.

 

What occured,

after cat, and o2 sensor i was still high on my high rpm HC's. which was really strange because my problem befor was low end HC's. Either way, when i looked back on it the one thing i did(other than new o2, and cat) was corrected some issues with my AB valve(i had some cracked lines, and im not sure if it works either way) in a nutt shell this was when my HC's went up(after connecting and repairing ab), and now i have alot of backfire.

 

I noticed that if i let air into the AB valve hose(the part that connects to the intake) it backfires real bad, but if i completly block it off(I put a hose cap on the tube comming from the intake maniforld) it clears up a bit.

 

Even with the intake manifold AB intake capped i still get some backfire at high rpms, so my next step was i disconnected the O2 sensor(from the harness). This even made it run a bit smoother, but still some backfires, especially if i lower rpm's(around 2k) in 3rd gear or so.

 

Im completly stumped, i didnt have this issue before i started with a new cat, o2, and installing ab, now even if i disconnect them im still backfiring.

 

any help appreciated, and ill toast a beer to you.

 

Also, now that my emissions has past(for the next 2 years), I dont mind disconnecting, or completely removing any emissions gear(as long as it makes me run better)

 

Thanks again

[JamesRich]

You are probably running a bit rich. Do you have any exhaust leaks? When you let off the gas a vacuum forms in the exhaust and fresh air gets sucked in through any leaks you have. The fresh air mixes with the unburnt fuel from the rich fuel mixture and the heat of the exhaust ignites.

James

[Scaramoche]

You are probably running a bit rich. Do you have any exhaust leaks? When you let off the gas a vacuum forms in the exhaust and fresh air gets sucked in through any leaks you have. The fresh air mixes with the unburnt fuel from the rich fuel mixture and the heat of the exhaust ignites.

James

 

yup, i think i do, i have a stud broke off on cylinder number 5, thanks ill check whats going on

[Scaramoche]

found the problem,

 

my AB valve(anti backfire valve) was seized.

 

I spoke with nissan for a replacement, but they didnt have one, and not sure how long it would take to get one. So either way, this morning(befor i did my suspension). I took off the ab valve off soaked it in bolt penetrator, had a couple cups of coffee, then flushed with 2 cans of brake fluid, dryed, and reinstalled.

Bingo!

it worked, and works well.

 

No more backfires

[Precise1]

I love the easy fixes...

 

B

[Tungsten]

Just out of curiosity, where is this valve? Is it a TBI thing?

[Scaramoche]

Just out of curiosity, where is this valve? Is it a TBI thing?

I do have the throttle body, and the AB valve is connected to the front of the airbox via a hose. This hose connects to the front of the ab valve. The top of ab valve has a vacuum line comming from manifold and at the bottom of AB valve has another hose which connects to the intake manifold(basically feeding fresh air into the combustion chamber.

 

Ill try and get some pics for ya later today

 

EDIT

actaully found a pic 1path did that shows the ab valve

 

http://www.nissanpathfinders.net/forum/index.php?showtopic=23251&st=0&p=416253&fromsearch=1entry416253

Edited June 25, 2010 by Scaramoche