Alternating power, rapid backfire

[Lawlipop]

Stock 2G. Has a vented BOV that I can't recirculate, so I need a new one. I know the symtoms of venting, and don't want to do it. But that's not the cause.

In lower rpms it feels like its pulling timing, loss of power until I get up to about 3k rpms, that's under light acceleration. If I step on the gas, it backfires, like rapid backfire. Its not so much like the loud pop you normally think when you think of a backfire. It's like a machine gun popping. Now if I take it nice and easy under acceleration I can get up there till I have it wot.

When I'm cruising, I can feel the car lose and gain power slightly. It will slowly lose power, then gain it back really quick, then lose it.

Got new plugs and wires, gapped at .28. New coolant sensor (had the code).

 

[Crash429]

Maybe try new fuel filter or fuel pressure regulator seems like its maybe starving for fuel, or cld maybe be runnin a lil outta time

 

[Lawlipop]

What's cld? How would I test the fuel pressure?

Haha, ok cld = could.

Well the mechanical is in time, and there's no way to adjust the ignition.

 

[KFred 513]

Have you checked all of your intercooler piping? Sounds like you could have a bad boost leak. Possibly a coupler blew apart or something of that nature. I'd do a quick BLT to make sure you have a solid intake before you go buying anything.

Is that BOV jacked up? It could be stuck open, pushing any pressure right out of your intake. If its not intake it sounds like ignition. Check to make sure you have spark at all four plugs. If you have spark make sure all four injectors are getting signal to fire.

My guess is your relying on all motor to get you where your going. Any hard acceleration will build boost, the MAF will read higher airflow, and your ecu will add fuel. If the air isn't making it to your cylinder, that extra fuel will have no air to atomize with.

Post back with results

 

[Lawlipop]

No the bov is fine, just that it has no way to recirculate. It's aftermarket. It seems to build boost just fine, but if I press down the gas all the way too fast, especially at any rpm below 3-4k it does it.

Also, when I'm going from a start, or switching into 2nd, it will sputter really bad like its about to die, and I just press down the gas and it goes back to normal. (but I can still feel the hesitation)

 

[n0de]

Is anyone thinking the possibility of Ignition timing being off? im not sure what to recommend for this guy to check first.

 

[Lawlipop]

I'm going to do a boost leak test, even though everything seems pretty solid. But I don't think there's a way to adjust ignition timing on a 2g.

 

[kayosfrawg]

Have you considered the MAF being bad? easiest way to check it is if you have buddy with one you know is good and just swap it onto your car and see if that fixes the problem.

 

[mchustle]

Sounds like a fuel filter to me. When is the last time it was changed?

 

[Lawlipop]

Well my boost leak tester is missing, so that sucks. Pulled my spark plugs, they have a little over 100miles, covered in a black carbon and the electrodes are white.

 

[Crash429]

There's accually a fuel pressure gauge made for testing it I jut bought one from summit racing, but maybe ask a few of your buddy's if the got one or take it to advanced auto or autozone I'm sure they will let u borrow one or check it free for you

 

[Lawlipop]

Have you considered the MAF being bad? easiest way to check it is if you have buddy with one you know is good and just swap it onto your car and see if that fixes the problem.

Tried that. I have 3 mafs.

I'll see if a parts store has a fuel pressure tester. Doesn't carbon build up on spark plugs mean you are running rich? Also, can an O2 be messed up and not give a code? I guess it's possible that a previous owner put an upgraded fuel pump on it, I haven't ran it hard since I bought it, needed a tps sensor. I adjusted that by turning it till the resistance went to zero method.

Couldn't this be from running too rich? I'm more worried about the normal driving problems (which is probably hand in hand with the wot problem).

Feels like its bogging down. And when I go from a stop it will start to misfire or something, unless I give it a bunch of gas. And the way I get it to stop misfiring is to give it more gas. I doubt it's a boost leak, because of the problems when there's no boost, and the fact it can build boost if I do it slowly.

I haven't replaced the fuel filter, but it seems to me it is running more rich than lean since it has black crap on the spark plugs.

 

[KFred 513]

Him, I know that when I raced MX a white electrode meant you were hot (lean) black was cold (rich) and a tan color was on the money.

Have you tried spraying carb cleaner around the intake manifold with the car running? If the idle drops or the car stalls you have an I take leak.

I'm not too familiar with the ignition system on this but its controlled by the ecu according to the signal from the cas. Make sure your sensor is plugged in. Maybe you can borrow one from someone to eliminate that as a possibility...its probably one of those simple fixes that is just a big headache to diagnose

 

[Lawlipop]

Him, I know that when I raced MX a white electrode meant you were hot (lean) black was cold (rich) and a tan color was on the money.

Have you tried spraying carb cleaner around the intake manifold with the car running? If the idle drops or the car stalls you have an I take leak.

I'm not too familiar with the ignition system on this but its controlled by the ecu according to the signal from the cas. Make sure your sensor is plugged in. Maybe you can borrow one from someone to eliminate that as a possibility...its probably one of those simple fixes that is just a big headache to diagnose

Here is what I'm talking about, all black, with a white ground electrode. They all pretty much look like this. I'm replacing them tomorrow with the fuel filter, but I need to find out whats causing it. I hope it's not the cas, I'm not getting a cel for it, and its located under the cam gear, got a 95..

And I think we can rule out some sort of air leak, idles fine, well sometimes a little low, but I have a problem whether it's 0 psi or 10 psi. Spooling or not.

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[91-GS]

Check the injectors, they might not be working properly, giving too much fuel, making the engine run rich.

 

[Lawlipop]

Check the injectors, they might not be working properly, giving too much fuel, making the engine run rich.

Could be a possibility, but for every injector to be giving too much fuel it would have to be from really high fuel pressure or maybe an ecu problem.

Last night just driving with light throttle it was pretty bad, when load is put on it in low rpms it misfires, worst being starting out in first. I guess too much fuel could cause this, because the spark plugs are black (but they are also dry). But when it misfires it feels more like lean.

Anywho, going to work and the. Replacing the spark plugs and fuel filter. Will report back. Anyone know if the front O2 could cause this without a CEL?

 

[Lawlipop]

Ok here's where I'm at. I first did the spark plugs to see if those were it, and it seems to drive fine now. I only took it down the road and back. I'm going to drive it a little more today. Seems like something ruined the spark plugs because they only have 100 miles on them. So I'll see if it comes back by checking the spark plugs in the next few days.

 

[ChiTownHussla]

Need some oxygen sensors are known to become lazy over the time and will not throw code because there in the parameters just very slow

 

[Jessi]

I would seriously look into the o2 sensor. That thing can cause odd issues to happen when its going bad.

 

[Lawlipop]

It pulls much better with the new spark plugs, but is reverting to poor driving under light to mid throttle. Doing the O2 tomorrow. If that doesn't work, pulling the fuel pump and making sure its stock. Or vice versa.

Well you'll never guess what one of the major problems was. It was intact the O2, buuut the O2 wasn't bad. The guy I bought the car from plugged the O2 into the cruise control and the cruise control into the O2.. They harnesses looked like they were stretched to to eachother and out of place. Checked for the proper wire colors and behod, they were plugged in wrong.

That fixed all my light to medium throttle problems. And I'm sure better gas mileage. And my backfire went from a loud, to now a "stutter" or muffled backfire. Still fast.