Backfire/bogging down

[zepher0n]

The past couple of months, maybe once a week when I start my car it acts like it's choking or starving for fuel. If I back out of a parking spot it may die/stall out. When I start the car again, it seems to be "backfiring" from the exhaust... kind of sounds like a rumbling sound when I shift or let off the accelerator. Honestly it sounds badass haha but I'm sure it's not a good thing. Sometimes I will hit the gas to go (not talking WOT, just normal driving), and the car sputters and has absolutely no power.

Some backstory: I got this car about two years ago. It was taken great care of (my aunt) and sat in the garage for two years before I got my hands on it. I immediately did a tuneup (plugs, wires, dizzy cap and rotor, timing, fuel filter and even a new fuel tank and filler spout/gasket). SLP exhaust, pypes offroad xpipe.

It's not tripping any lights or anything and isn't usually a problem. It may do this once or twice a week like I said, and even then once the engine warms up it doesn't happen anymore. I'm sure I have to change my air filter. I'm going to be adding a CAI soon though. Instincts tell me air filter and clean the MAF, but any thoughts are appreciated.

 

[white95]

I had a similar problem a few years back, but it wasn't intermittent like your issue. In my case, I eventually changed the oxygen sensors which fixed it. I also changed the fuel filter, fuel pump, cleaned the Idle Air Control/IAC valve, checked the TPS sensor voltage, cleaned the MAS, performed a high pressure fuel system clean, bypassed the smog pump and checked the timing. A lot of work that helped in other areas but not the stuttering/bogging situation.

 

[zepher0n]

Thanks for the input! I should look at changing the o2 sensors, they're probably needed even if they aren't the issue. I already have everything I need to clean the IAC and massair so I will do that, too. Anything else I should look out for?

 

[white95]

Vacuum leaks could also be suspect here..

 

[RichV]

A sidenote on the O2 stuff. When I ran my car last, I noticed I did not plug in the O2 harness (it's the round plug under the oil filter area). Anyway, I plugged it back in and the car did not run good. Not as bad as yours, but definitely some sputtering and backfire when I let off the throttle. I unplugged it and ran it like that all weekend, and it ran fine.

I probably would not do that on a street car, because you need the O2s for closed loop. But you could just unplug the harness to test.