popping/backfiring problem

[1990AWD]

car info: basically stock '90 AWD 5spd with mbc, boost gauge, fuel pump rewrite, and stock open dp

problem: lately my car has been making a real bad popping/backfiring noise only above 4k rpm, even under half throttle or WOT. It was doing this one day, not the next, and then again the day after

what has been done: lately I put a new ignition coil on because the old went (was working much better until now) and plugs and wires are relatively new.

solution: blank, can someone help me please?

 

[GRAVEDIGGER]

Have you recently changed your fuel filter? If not I would do that immediately as well as change the spark plugs. You say the plugs and wires are relatively new, but I would at least put brand new plugs in it.

 

[XiKeiyaZI]

Have you recently changed your fuel filter? If not I would do that immediately as well as change the spark plugs. You say the plugs and wires are relatively new, but I would at least put brand new plugs in it.

Don't mean the threadjack...


But a fuel filter... would that cause the above symptom on Decel as well?

 

[ramsack]

No. Your car should not be injecting fuel on decel with the throttle shut.

 

[XiKeiyaZI]

No. Your car should not be injecting fuel on decel with the throttle shut.

-trips-

>> Juuuuust questioning. That's all.

+1.

 

[1990AWD]

Have you recently changed your fuel filter? If not I would do that immediately as well as change the spark plugs. You say the plugs and wires are relatively new, but I would at least put brand new plugs in it.

The fuel filter doesn't have more than a couple thousand kms on it and same with plugs.

Any other ideas??


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[1990AWD]

Does anyone know whats wrong with my car??


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[boostNmetal]

Was that a Walbro 255 that you re-wired?

 

[1990AWD]

Was that a Walbro 255 that you re-wired?

no just the factory pump. trying to get all I can out of it


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[boostNmetal]

I would look at the plug wires again. I've had a set of wires go bad in no time at all before. Moisture in the plug wells will accelerate plug wire degradation.

 

[Dragon34x]

When was the last time you changed your spark plugs?

 

[2slow4utsi]

It's the spark plugs. I had the SAME exact problem. It would go something like "VROOOOMMMM pop pop pop pop" and you wouldn't move very far. Whatever you do DON'T run Iridiums. Go with your standard NGKs.

 

[dsmshae90]

Check your o2 sensor, check your spark plugs and the gap, check your wires, and check the compression.

 

[shockracer]

if the plugs are new i would check the coil pack next, don't ask me how im sure some one else can help with that, but i know of 3 other car's i've had that did the same thing

 

[1990AWD]

thanks for the replies, but the coil, plugs, and wires are all basically new. can't be more than 5000km on plugs and wires and 2000km on the coil. I will check to see if they are wet and dirty in the spark plug wells.

one thing I did try today was seeing if the O2 sensor was working. I unplugged it and the car didn't run any different. does that mean it's bad?


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[ramsack]

one thing I did try today was seeing if the O2 sensor was working. I unplugged it and the car didn't run any different. does that mean it's bad?

It could be, but that's not a real way of testing anything. The easiest thing to do would be to find the o2 wire in the passenger kick panel and tap an analog multimeter to it and find a ground for the negative of the meter. The wire is hard to find and you gotta untape or un-zip-tie the wire mess to find it. It's crammed up there. Then drive around and watch if it cycles on cruise and cycles on idle. If it cycles on cruise but not idle, you have an exhaust leak. If there is no movement you have a dead sensor or bad wiring.