Code deciphering
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Freshman User
Joined: Nov 2010
Posts: 39
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From: Ypsilanti, MI
Code deciphering
My 86 F150 4.9L I6 with TFI ignition is running rough like it's missing a cylinder or something. I've ruled out everything in the ignition because everything is pretty much new and all cylinders are getting a spark. I did the code reads and on the KOEO I get 11's (no issues) in both tests. I did the KOER test and I get 41R -HEGO HO2S sensor voltage low / system lean and 77R Operator error during Dynamic Response Test Wide open throttle not sensed.
I just replaced the O2 sensor and verified the wire had like 0.02 ohms resistance from the connector to the computer (sensor not present in test) I bench tested the O2 sensor before putting it in with a propane torch and measured voltage rise and fall between the connector and sensor body, so I don't think the sensor is actually bad.
When the reader sent the code 10 for the DR test, I floored the accelerator and left it at high idle for a second or two. It seems to throw this code all the time which I don't think indicates a direct problem just me not doing something right.
As a side note, the carb was rebuilt in the fall and ran great for a while after, fuel filter is newer so I don't think I have a fuel supply issue. I checked all the wires between ignition components and the computer connector and they all seem good with no shorts. As a side note, if I run it with out the SPOUT connector connected it runs smoother, but if the engine is at normal shift RPM's and I clutch/let off the gas it kind of back fires. Any thoughts out there?
I just replaced the O2 sensor and verified the wire had like 0.02 ohms resistance from the connector to the computer (sensor not present in test) I bench tested the O2 sensor before putting it in with a propane torch and measured voltage rise and fall between the connector and sensor body, so I don't think the sensor is actually bad.
When the reader sent the code 10 for the DR test, I floored the accelerator and left it at high idle for a second or two. It seems to throw this code all the time which I don't think indicates a direct problem just me not doing something right.
As a side note, the carb was rebuilt in the fall and ran great for a while after, fuel filter is newer so I don't think I have a fuel supply issue. I checked all the wires between ignition components and the computer connector and they all seem good with no shorts. As a side note, if I run it with out the SPOUT connector connected it runs smoother, but if the engine is at normal shift RPM's and I clutch/let off the gas it kind of back fires. Any thoughts out there?
Post Fiend
Joined: Jul 2004
Posts: 8,786
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From: Northern California
Code: 41: The sensor voltage is low because the engine is running too lean, or the O2 sensor is plugged. Try richening the fuel mixture screw on the carb.
Code: 77: Operator Error OR wide open throttle not sensed. Push the accelerator to the floor and take your foot off of it as quickly as feasably possible, don't hold it for two seconds as it will confuse the computer. If you still see a code 77, check the Throttle position sensor.
Code: 77: Operator Error OR wide open throttle not sensed. Push the accelerator to the floor and take your foot off of it as quickly as feasably possible, don't hold it for two seconds as it will confuse the computer. If you still see a code 77, check the Throttle position sensor.
Thread Starter
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Freshman User
Joined: Nov 2010
Posts: 39
Likes: 0
From: Ypsilanti, MI
Need a little reality check
I'm watching the ignition by putting the timing light on different plugs. Plugs 4 and 5 have weird flashing patterns, 4 will miss a couple flashes every now and then and 5 will have double flashes. Does that sound like profile ignition pickup deal or a module deal?
