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I have a basic computer question. How to determine if the computer is bad? I have a 1990 F150 351 4x4, new to me. Initially the highway mileage was 13mpg but now the road and dirt mileage is down to 10 mpg. The diagnostic test showed "None" as results for all the warm running condition. I changed the coolant temperature sensor but it still smell rich. I plan to do another mileage run. If it is still low mpg, I am thinking of a rebuilt computer (~$130).
Is there a simple test or is it back to the $mechanic with the tool or just spend the $?
TIA
Bill
When the computer goes bad they will either not work or start throwing error codes. Have you done the basics (plugs, wires, cleaning the injectors, air filter)? What are you using for a diagnostic test?
Thanks for the info. I have done the basics. The truck runs reliable but just low gas mileage (10 mpg) and smells rich. I shows no flashing enginecodes. I just read Broncobusters long thread so believe I'm on track for additional test. I got the newer Haynes manual that shows the diagnotic tests, much better than the old book.
Problably I'll test and replace the o2 sensor since it is old and I'm heading on a long elk hunt Wednesday. Just hard to haul gas.