Where to begin? 1974 Bronco with a 1993 Mustang 5.0 EFI
I needed a new battery the other day, as my 10 year old Optima finally died. I replaced it with a Deka Extreme AGM. All went well, started, ran, checked the alt output...everything was fine. Bronco ran great for about 10 minutes while I checked various parts of the charging system. I parked it and went in the house. Three days later I fired it up to move it into the garage to remove the top and now it wont idle and runs poorly. It starts just fine, every time. It revs up to about 2000 just like normal and when it comes back down it just falls on its face. Sometimes it dies completely, and other times it will chug along and rev up to 2000 grand every 5-10 seconds falling to barely running in between.
Here are the specs.....
1993 5.0 short block with a Explorer 5.0 upper. Painless 5.0 Bronco harness with stock exhaust manifolds. Its running a stock 1993 Mustang ECM.
I pulled codes and found all the ones that are expected.
31-67-81-82-84-85 There is no EGR or Thermactor or Auto Trans.
It will not perform the KOER test at all. I have run the engine with every single sensor and input unplugged at one time or another and not one of them tripped a code. I tested every sensor at the sensor and at the 60 pin. Every one of them tested within parameters. IAC-Both O2s-TFI-MAP-MAS-TP-IAC-ECT-ACT...I swapped out the following parts with known good or new just as a test...Coil-TFI-TP-and the ECM. I checked all the pins at the ECM that were supposed to have power and ground or VRef...all good. I unplugged (one at a time) Every single sensor just to make sure that none were failing in a way that could ground short or short to power. No Change. I changed the fuel pump because it had a lifetime warrenty...40 PSI wile running and dips no lower than about 34. I pulled the dist cap and put the engine at TDC to make sure the timing chain did not crap out on me.
It will run if you hold the throttle open but it back fires through the throttle body and sputters and does not want to run.
I am really at a loss...I don't know anything else to check. Just as a background on me, I am well above your backyard mechanic. I worked as an electrical tech at Ford for about 10 years. I know my way around, and that makes this even more frustrating.
Any ideas would be greatly appreciated.
I needed a new battery the other day, as my 10 year old Optima finally died. I replaced it with a Deka Extreme AGM. All went well, started, ran, checked the alt output...everything was fine. Bronco ran great for about 10 minutes while I checked various parts of the charging system. I parked it and went in the house. Three days later I fired it up to move it into the garage to remove the top and now it wont idle and runs poorly. It starts just fine, every time. It revs up to about 2000 just like normal and when it comes back down it just falls on its face. Sometimes it dies completely, and other times it will chug along and rev up to 2000 grand every 5-10 seconds falling to barely running in between.
Here are the specs.....
1993 5.0 short block with a Explorer 5.0 upper. Painless 5.0 Bronco harness with stock exhaust manifolds. Its running a stock 1993 Mustang ECM.
I pulled codes and found all the ones that are expected.
31-67-81-82-84-85 There is no EGR or Thermactor or Auto Trans.
It will not perform the KOER test at all. I have run the engine with every single sensor and input unplugged at one time or another and not one of them tripped a code. I tested every sensor at the sensor and at the 60 pin. Every one of them tested within parameters. IAC-Both O2s-TFI-MAP-MAS-TP-IAC-ECT-ACT...I swapped out the following parts with known good or new just as a test...Coil-TFI-TP-and the ECM. I checked all the pins at the ECM that were supposed to have power and ground or VRef...all good. I unplugged (one at a time) Every single sensor just to make sure that none were failing in a way that could ground short or short to power. No Change. I changed the fuel pump because it had a lifetime warrenty...40 PSI wile running and dips no lower than about 34. I pulled the dist cap and put the engine at TDC to make sure the timing chain did not crap out on me.
It will run if you hold the throttle open but it back fires through the throttle body and sputters and does not want to run.
I am really at a loss...I don't know anything else to check. Just as a background on me, I am well above your backyard mechanic. I worked as an electrical tech at Ford for about 10 years. I know my way around, and that makes this even more frustrating.
Any ideas would be greatly appreciated.
