Someone gave me a 240 sedan a while back, story was the timing belt broke, they put a new one in, it ran, but never did run right..... Once I got the timing marks lined up and reinstalled the belt (one tooth off), the thing fired right up and has run great for the past couple of months. I redid the brakes, fixed some front end issues & gave the car to my 16 year old son to drive (for the record, he got down & dirty with me putting the thing on the road, this has been a learning experience for him, not a free lunch).

The car starts instantly, runs smooth, pulls strong, but it's always been running a bit rich. The odometer quit at 215K, there're no MPG figures, but the exhaust smells rich even when the engine is warm, and the plugs read out toward the black end of things after a fast run on the highway. The thing seems to use a lot of gas, I'd guess high teens to low twenties on the basis of number of 30 mile trips to town per tank. We've renewed all of the vaccuum hoses, the fuel pressure regulator does not have an internal leak (no gas at the vaccuum hose); the wiring in the engine compartment looks sanitary, connections to temperature sensors look good, the air intake doesn't have an old sock stuffed into it.

I'm thinking the oxygen sensor might be toast, and / or I suppose a temperature sensor could be bad. Would someone please post for me the diagnostic test values I should be getting off the O2 sensor and temp sensor? Also, I gather there's a low dollar O2 sensor available from some late model Ford Mustang that will swap in, which year & part number? I know this has been discussed endlessly in other posts, but I'm having a hard time coming up with the info using the search engine on this site (no doubt my own incompetence).

Any other thoughts on lousy MPH?

Thanks in advance, Nick Evans