Codes Codes Codes
Freshman User
Joined: Jan 2003
Posts: 28
Likes: 0
From: Duluth, MN
Codes Codes Codes
[updated:LAST EDITED ON 04-Jan-03 AT 01:54 PM (EST)]I have a 95 F250 with a 351w. Check engine light popped on and I pulled the codes. Key on engine off gave me a 23, so I figured I best start there. Checked the TPS and everything ohms good and seemed to change smoothly when I moved the throttle by hand. Connected it back up and KOEO passed.
Cleared out the codes and test drove it. Yup check engine again. KOEO still passed and memory had 172 code O2 sensor fault/lean. Tried a KOER test and got a 538 throttle moving during cyl balance test.
Trying to make sense outta this. Not sure which sensor is going bad. Also mileage has started to really suck sometimes. Truck has 100K miles now. Any thoughts would be appreciated.
Cleared out the codes and test drove it. Yup check engine again. KOEO still passed and memory had 172 code O2 sensor fault/lean. Tried a KOER test and got a 538 throttle moving during cyl balance test.
Trying to make sense outta this. Not sure which sensor is going bad. Also mileage has started to really suck sometimes. Truck has 100K miles now. Any thoughts would be appreciated.
Post Fiend
Joined: Nov 2002
Posts: 9,987
Likes: 7
From: Memphis, TN
Codes Codes Codes
>I have a 95 F250 with a 351w. Check engine light popped on
>and I pulled the codes. Key on engine off gave me a 23, so I
>figured I best start there. Checked the TPS and everything
>ohms good and seemed to change smoothly when I moved the
>throttle by hand. Connected it back up and KOEO passed.
>
>Cleared out the codes and test drove it. Yup check engine
>again. KOEO still passed and memory had 172 code O2 sensor
>fault/lean. Tried a KOER test and got a 538 throttle moving
>during cyl balance test.
>
>Trying to make sense outta this. Not sure which sensor is
>going bad. Also mileage has started to really suck
>sometimes. Truck has 100K miles now. Any thoughts would be
>appreciated.
All '91-up use 3-digit codes, so you read it wrong when you got 23.
172 probably means you have a vacuum leak - use a 3' piece of garden hose as a stethoscope to find it.
738 is "Insufficient RPM change (operator error) during Dynamic Response Check", which means you didn't stomp the gas pedal when the light flashed - read Haynes carefully for the correct moment to press the pedal.
>and I pulled the codes. Key on engine off gave me a 23, so I
>figured I best start there. Checked the TPS and everything
>ohms good and seemed to change smoothly when I moved the
>throttle by hand. Connected it back up and KOEO passed.
>
>Cleared out the codes and test drove it. Yup check engine
>again. KOEO still passed and memory had 172 code O2 sensor
>fault/lean. Tried a KOER test and got a 538 throttle moving
>during cyl balance test.
>
>Trying to make sense outta this. Not sure which sensor is
>going bad. Also mileage has started to really suck
>sometimes. Truck has 100K miles now. Any thoughts would be
>appreciated.
All '91-up use 3-digit codes, so you read it wrong when you got 23.
172 probably means you have a vacuum leak - use a 3' piece of garden hose as a stethoscope to find it.
738 is "Insufficient RPM change (operator error) during Dynamic Response Check", which means you didn't stomp the gas pedal when the light flashed - read Haynes carefully for the correct moment to press the pedal.
Elder User
Joined: Dec 2002
Posts: 608
Likes: 0
From: TAOS NM
Codes Codes Codes
don't it just bother you trying to deal with these computerized trucks? this just makes owning newer trucks suck ,it takes away all the fun of working on your truck ha.:-staun i have 1991 f-150 351 windsor and i want a 54 y block, cause i just had enough with this codes and senors sh--.anyway good luck
Post Fiend
Joined: Nov 2002
Posts: 9,987
Likes: 7
From: Memphis, TN
Codes Codes Codes
#E<<, NO!!!!!!! 
:-X23 I wouldn't go back to chasing vacuum leaks, cracked diaphragms, fouled jets, & 1,000 tiny adjusting screws for all the tea in China! 
I spent a LOT of time & about $500 more than a plain rebuild would have cost me when I converted to EFI, and I'd do it all again 5 times rather than go back to a carb'ed vehicle. 
I HATE
carbs! 
:-X23 I wouldn't go back to chasing vacuum leaks, cracked diaphragms, fouled jets, & 1,000 tiny adjusting screws for all the tea in China! I spent a LOT of time & about $500 more than a plain rebuild would have cost me when I converted to EFI, and I'd do it all again 5 times rather than go back to a carb'ed vehicle. I HATE
carbs! 
