I have recently bought two code readers for my truck and none of them work. the truck has an obd1 computer with an obd2 hook up for it. MY obd2 scanner wont work on it and my obd1 reader wont either. What can i do so that it will read it? I bought thses becouse my motor is getting less than 8 mpg and i want to get freeze fraim onthe motor.IM putting new sparkplugs and O2 sensor on it to see if that helps.But if u have any suggestions to why its bad gas milealage let me know.

 

On the scanners, you have to get one that specifically states that it will work with the OBD1.5 (as I call them) vehicles. I do not know if freeze frame data is available with this system though.

Anyway, regarding your mileage problem. I would start with a tune up if you haven't already. Plugs, wires, cap, rotor, possibly including the upstream O2 sensor (the one closest to the engine in the y-pipe).

After that, I would test the fuel pressure, specifically doing a leak down test. Pressurize the system, then watch the pressure after you turn the key off. It shouldn't drop more than 2-3psi. If it does, you have a leak somewhere in the system. Most likely it is internal to the plenum. If it is a slow leak, it is possible that the 'nut kit', the internal fuel lines, has sprung a leak. If it drains fast, then your FPR is probably shot.

 

its on a rebuilt motor. it was new plugs, rotor wires and cap i also put a new spider in it.

 

Did you also replace the 'nut kit' (internal fuel lines)? If not, that may be the cause of the leak.

Bad gas or condensation in the gas can cause poor mileage as well. Have you tried different gas stations? I notice a 2mpg difference between the Mobil (poor mileage) and the Sunoco (good mileage) stations in town.