I just installed a mac offroad h-pipe. Is it normal for this alone to cause check engine light to come on on a 95 5 liter? It comes a few minutes after driving once car warms up. If I shut the car off it goes off and then comes back on in a few minutes. I thought this might happen, but if there is any way around it I would love to know. thanks.

 

Its probably because the rear o2 sensors are not picking up a signal reading saying that the "cats" are functioning properly. That can be turned off in the ECU via a tune or I know on 4.6L cars you can run mil-elimnators, but I am not sure if they work on a 5.0.

 

Ok after some research, i think the mil elims only work for 96+

 

Yes, turn off your 02's and you should be good to go.

 

how do I do that? and is any of this going to decrease my mpg (not counting my heavy foot).

 

The mpg shouldnt change. You're not damaging your engine and it isnt running any less efficiency. If anything, your mileage should actually go up. Except of course for the lead-coated right shoe.

 

I would head down to a performance shop that knows Mustangs, hopefully you have one in your area. They can disable them and also tune your car for best A/F ratio and such. If you want it to run right this is what I would do.

 

thanks. I willl try and do that.