Check Engine Light
 

I have a 96 GT and I just added a K&N air filter and an off road H-pipe and now my check engine light stays on. Does it have to do with the MAF or maybe because the Cats where removed? Everything seems to run fine so is it something I should even worry about?
Thanks for the help.

make sure your o2 sensors are plugged in. sometimes i've heard that back pressure (egr solenoid)is affected by off road h-pipes on the 4.6. if you saturate the k&n then your maf feels like its in the poisiedon adventure; it gets that gunk all over the sensor and destroys it. and it will set a lean condition for a code.

I would lean more to an O2 sensor than an MAF problem from the K&N. You might want to check for any trouble codes from your computer.
Hope this helps...

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98 GT
Dyno-Max cat-back exhaust, 3.73 gears, Steeda shifter, Ford Motorsport Underdrive pullies, 87mm MAF and Roush cold air kit...

I believe it has to do with the offroad H-pipe. When the cats are removed on the newer stangs (not sure if it's 94+ or 96+) you have to get some MIL eliminators for the computer to compensate for losing the cats. Not sure where you get them but when you put them in, your CE light will not come on.

It's the o2 sensors on the 96-up cars that are the most sensitive since OBD2 came out. Dallas Mustang sells the MIL eliminators to disrupt the signal. When I had an offroad pipe on my 96 the same thing happened.

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(96Cobra/softtop-3.73,almdrvsht,fancontrl,steeda sbfrmes+shifter,eibachspgs,pulleys,Bassani X pipe,C&L 80mm
Cobra DYNO 301rwhp horsepower
93 Ford Probe Gt(slower but turns)

be wary though, the mass air flow sensors on these cars do not like K&N filters. read the other post on this topic about a check engine light.