Hi there, I have recently purchased a 1991 B2600i 4x4 with 217,000kms(134,000miles) that has some performance and drivability issues that I am having trouble diagnosing, It has a five speed manual trans and 235/75r25 tires, seems to be in very good condition. Any help or advice would be greatly appreciated! I will start with the observed issues, 1- poor gas mileage, 18mpg on the Canadian gallon, which equals just under 16mpg on the US gallon, that's on trips to the city so mostly highway. 2-hard starting in cold weather, seems to turn over longer than it should to start all the time, but in any weather much colder than zero Celsius it is near impossible to start unless plugged in. 3-past mid throttle miss or jerk. Runs fine to mid throttle but when you step into it has a serious hesitation. Attempted diagnosis. 1-checked timing, bang on, new plugs and wires 2-new starter and battery, turns over fine 3-tried grounding diagnosis pin to get engine light to flash to relay any trouble codes, light just stays on when ignition is turned on 4-oxygen sensor appears to be new 5-mass airflow sensor was also changed with a used one from wrecker, did clean it but no difference in performance 6-checked throttle position sensor, found a bare but unbroken wire, sealed wire, tested it, graduates from 0-5.2volts smoothly on opening, seems to function fine 7-changed the coolant temp sensor because it was relatively inexpensive, no difference in performance My theory it is likely either the intake air temp sensor, mass airflow sensor, or faulty new oxygen sensor which are all expensive to replace so I would like to know which one so I'm not just throwing parts and money at it. I have read of some guys having faulty ecu's, could this be possible considering it doesn't seem to want to give the error codes as well?

 

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