1989 Ford Ranger No Torque and power/ Hesitation past 3000R

IANHIESTAND

MEMBER
1989 FORD RANGER

Engine Performance problem
1989 Ford Ranger 6 cyl Four Wheel Drive Manual 57, xxx miles

I have been troubleshooting for months and cant figure it out. Im an avid mechanic and cant get the problem fixed. The truck starts and idles fine but, while driving I have no power and it wont rev past 3000rpm. It wont rev past 4000rpm with clutch engaged. I hace replaced: Fuel filter, plugs(gapped), wires, air filter, MAP sensor, Throttle Position sensor, Idle Air Control valve, TFI-IV Ignition Module(on distributor), Coil, PCV valve and also done fuel presssure test(40psi at idle, 37psi at 3000rpm)NO vacuum leaks. Sometimes it will start up and die but, turn switch on-off a few times and it will run but still hesitates while driving. I ran codes and get code 11(System Pass). New Mello-Tone single exhaust. No odd smells, 93 octane run in it since new. I dont think the Catalytic Converter would be the problem since only 57, xxx original miles but, problems started 1 month after exhaust work. My only culprits would be ECM or Catalytic Converter, everything else has been replaced. Im hoping you have an answer because I cant figure it out. Thanks

1 Reply

MIKE H R

MECHANIC
3,094 POSTS

I don't know if I have the right answer for you, other moderators are more up on the system than me. A question, after you drive the truck for a while especially at night and you shut the truck off can you see the catalytic converter give off a red glow? You can try disconnecting the negative side of battery. After a couple of minutes reconnect the battery. In vehicles after 1993 the vehicle will have to be driven about 50 miles before the system ecm resets itself. With the new exhaust and this happening after the exhaust was put on I wonder if the information in the ecm is doing it.