SHO Woes, surging, air box popping, flooding

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Bigmatt

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Hey all,

I have a 94 MTX with underdrive pulley, upgraded MAF, y-pipe, and dynomax exhaust. Most recently it started acting up. Some days the car runs just fine, and then as if a switch flipped, it bogs down, I hear popping from the air box, and it won't rev, or go at all. I limp it back home, turn it off, and then come back later, then it's fine.

On two of these occassions the cats were glowing red, which tells me whatever it is, it's running rich. Would that ruin the cats for just two times of having that happen? They are new cats, and I don't think I ruined them cause I can drive it just fine later.

I replaced the O2 sensors, the air box temp sensor, the throttle position sensor, and today, the MAP/BAP sensor. I think it might be the map sensor because it acts up mostly when it rains. We'll see if the BAP replacement cures the problem. I also recently did the 60k, so the crank position sensor was changed, and it has new plugs and wires.

I don't have a scanner to pull the codes, and the check engine light only comes on when it acts up. I was thinking of taking it to a shop, but they've all said they can't do anything unless they catch it in the "act." I am nervous because I have to drive it back across the country (on military temporary duty) Any thoughts?

Thanks kindly,

Matt
 

itwonder

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Try unplugging the MAF when it acts up and see if it runs better.
 

SuperHO

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when you say "upgraded MAF", upgraded with what and how long have you had it?
 

jayro

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I've also heard bad things about the c&l mafs. They are very hit and miss. Pull the codes with the paperclip method and see what comes up. Glowing cats is usually a rich condition. If you hadn't just replaced the o2's I would go there first.
 

Art5

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when you pull cam sensor check if there is any oil leaking from the seal or not. I had a problem with one car like that before. Too much oil getting clogged up in there. And yes, I would also try putting stock maf on and see how it goes from there.
 

Bigmatt

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Pulled the codes today and this is what I got: 21 Engine Coolant Temperature (ECT) sensor out of range - ECT. I bought a new one, haven't installed it. Hopefully that fixes the problem, but I noticed the wire on the sensor to that thermostat outlet was almost off too. Maybe that had something to do with hit. I'm glad I changed the o2 sensors, bap, tps, and air temp sensor cause it's running like a bat out of **** when it does run!
 

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