8mpg need some ideas on what is wrong.

[mustang_jr+]

I havea 96 cobra that burns about a quart a month, and gets in the last month perhaps 8-12mpg.

I had an imrc error, did the seafoam thing, and code wipe and it's been fine
since. However, on very hot days I can feel the engine lurch once the plate opens.

Any ideas? I live in once of the worst areas to own a cobra,
northern NJ. It's at the best, 5.0 places. No one wants
to touch a 4v.

I get this feeling like it's incredibly out of tune or has some problems
with compression / valves.

I am changing the plug wires and plugs this weekend, and cleaning the
maf.

Car has 80K on it. I'll record some video today, maybe you can pick out some noises.

Any ideas what would cause such bad mileage? It doesn't even smell like it's burning rich.

 

[Built98GT]

New plugs and wires definatley.You might need to do an engine flush. Did the car sit around for a long time? <--due to the low mileage? I would suggest having a Ford dealership look at it if there is one in your area.

 

[mustang_jr+]

I was thinking the same thing, the plugs and wires.
I was thinking of a compression test too.

The car as far as I know didn't sit, but it had a 90% worn
stock clutch I had to replace.

So far it has pulley, long tubes, x pipe hiflow cats, borla mufflers.
Larger TB, larger MAF and C&N, gears and pro 5.0.

I'm not even getting 140 miles to a tank.
I just got the wheels changed / balanced
oil changes are very regular.

I'm puzzled as the car doesn't have any signs of running rich at all.

Mileage got worse after seafoam treatment, but engine reponse improved
greatly.

 

[Price1]

What kind of long tubes?? Not MACs I hope because there's LOTS of oil burning problems with these LT's. Do a search on any SVT forum and you'll see.

 

[mustang_jr+]

Local ford guy said to check my o2 sensors.

I'm going to go clean the maf and then see what happens.