axis11

For the past two weeks, the car has been having random exhaust backfire( I think).Its not really loud and you can hear it only when you are at the rear of the car close to the exhaust. You wont hear it in the engine bay but you could feel the vibration its causing. Its noticeable only at idle. It doesnt seem to be having a misfire. I have normal power while driving. It just started acting up all of a sudden and continued since then. No CEL. Car has very few sensors in it. None on the exhaust and cat. Im thinking it could be running rich and cat might be worn. Their is but a slight smell of gasoline on the exhaust but very clear and no visible smoke. Car has 320K miles on it and the exhaust seems to be still stock. Help!

sfar785

is it backfiring from the intake manifold or the exhaust?

axis11

only backfire on the exhaust or should I say after fire.

sfar785

stock exhaust?

grumblemarc

iTrader: (4)

Last tune up? Check timing? Does CEL actually work?

axis11

Not exactly stock. There are now two mufflers and tailpipes connected in parallel. The parts are all stock though. But the changes were done two years ago with no problem since.

sfar785

i'm guessing you're running rich and not all of your fuel is getting burned in the combustion chamber, it's getting sent out the manifold. When it hits the hot exhaust piping, it ignites causing the backfire. So check your plugs/plug wires..

also, you're running a dual exhaust? Could be lack of back pressure because our motors weren't meant to run dual exhaust, our motors have the exhaust and intakes they have to let the motor breathe a certain way, once you start ****ing with **** and changing things you're gonna get some repercussions. I have a 2 1/2" exhaust running from my header to my muffler, no cat no resonator, it backfires when i left off the gas at high RPM's due to the lack of back pressure.

axis11

CEL is working. Two months ago I got a CEL for iacv. Cleaned it and problem was gone. Plugs were maybe a year old. Wires were there since I got it 4 years ago. So I took my friends dizzy cap and wires and tried it on,same problems. Cleaned and adjusted spark plugs, replaced air filter. I still have a lot of power and can still get to max speed limit and max rpm.I adjusted valve clearance the other day hoping it was coming from the valves. Have to check ignition timing tomorrow.

sfar785

put a single exhaust on it...it'll clear the problem right up

axis11

I could always take one muffler out. And besides the modification was two years ago.

sfar785

so it just started doing it? its from your car running rich then

axis11

Could a dying catalytic converter be the one to take the blame? The car has 320K+ miles on it.

sfar785

yes, yes that can be the cause because that means unburned fuel is getting through the cat and igniting in your exhaust

axis11

Shouldn't I be getting more backfires when im accelerating or moving fast and then let go of the gas? Weird coz it fires only on idle or low rpms.

axis11

I uploaded some sound and videos.