Getting horrible gas mileage!
 

I am around 15-17 MPG now. It's been going on for almost a month now. I am used to 18-23. I put about 35 miles on the car daily and 30 of them are highway. I've done no mods recently and my fuel filter only has 5K on it. Any ideas or has anyone recently had problems?

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1997 Cobra (Black on black), C+L 80mm MAF, K+N filter, Pro 5.0 shifter, BBK Springs, Taylor Wires, 2 Chamber Flows, ASP Pulleys, BBK off road H pipe.

Check your plugs and wires. Look the wires over good for looseness on the coils or plugs or maybe even bare wire on the headers or whatever. Check your plugs and the plug gap. May need new ones. How clean is your air filter? It'll run rich if your air filter is dirty. How's your air pressure in your tires? That can also make a difference. Run some fuel system cleaner through it such as for the injectors, etc. Are you consistently getting your fuel from the same station? You might change stations. Maybe getting bad fuel, water in it, etc.

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1996 Mustang GTS

I've done all this except the plug gap. I'll try that this weekend depending on the temp outside. I change gas stations frequently and also run gas line anti freeze from Prestone, through every third tank. Thanks for the advice!!

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1997 Cobra (Black on black), C+L 80mm MAF, K+N filter, Pro 5.0 shifter, BBK Springs, Taylor Wires, 2 Chamber Flows, ASP Pulleys, BBK off road H pipe.

I agree completely. I have a 96' Cobra with 28,000 miles on it. About 3,000 miles ago I started having the same problem, I changed my plugs and air filter and it was fixed. I guess these Cobra's can really eat up plugs once the gap gets a little bit over specs. I used autolite platinum plugs...

All good now!! That was easy. Man, that sure was a huge difference just for a dirty filter and 10K mile worn plugs.



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1997 Cobra (Black on black), C+L 80mm MAF, K+N filter, Pro 5.0 shifter, BBK Springs, Taylor Wires, 2 Chamber Flows, ASP Pulleys, BBK off road H pipe.