i have an 88 tbi motor. Just recently the the service engine light came on. went to check for the codes and it is not reading any thing. tried a code reader and a faithful paper clip, neither work. the first code that is suppose to appear is a code 12 meaning that the computer is in diagnostic readout mode. it didn't do this. mothing happed. no light were blinking damn it. as i was following in the chevy shop manual for the 88, it had a section for when it doesnt readout a code 12 when the terminals are grounded. what the manual is saying is that is could ba a faulty prom, ecm, or some mem-cal thing. any ideas on how to diagnose this problem. any help is appreciated. dag on thing is burnin twice as much gas as it should. high sulfer smell is gas, very coldnatured on crankup. if it ends up that i need a new chip for the computer, who make the best after market chip that increases power and fuel economy? how much $ also?