I pulled the codes on my 1990 F-250 4x4 5l 302 zf-5 speed aprox. 250,000 miles.

As said I pulled the codes and heres what I got with the definitions.
KOEO (Key On Engine Off)
12-Cannot control RPM during ER Self-Test high RPM check.
93-Coast clutch solenoid circuit failure (E4OD).
34-PFE or EVP circuit above the closed limit of 0.67 volts.

KOER (Key On Engine Running)
21-ECT out of self test range 0.3 to 3.7 volts.
41-No HEGO switching detected always lean (right side)
33-EGR valve opening not detected.
77-System failed to recognize brief WOT during Dynamic Response Test (user error).
52-Power steering pressure switch always open or closed.


I have been noticing that the truck will have good and bad days. On a good day it will have great power and somedays it just seems gutlesss. The check engine light will sometimes be on also. I know some ofthe wires are broke comin off the O2 sensor butit didnt throw that code. soheres my questions
1.Why didnt it throw an O2 sensor code?
2What are alot of the sensors? Are they easy to replace?
3.Are any of these codes serious?
4.When am I supposed to do the brief WOT during the test?
5.Why did I get code #93 if I have a zf and it lists it as E4OD only

Thanks for any help. Im 17 and have alot to learn! Josh

 

Hey Josh, a good way to learn is to read a manual Haynes and Chilton etc.

1. it did #41
2. ECT is the engine coolent sensor, make sure the radiator is full first off.
3. best code is no code
Fuel Injection Technical Library » Engine Coolant Temperature Sensor (ECT)
Fuel Injection Technical Library » EGR Vacuum Regulator (EVR)

 

How did you pull the codes? Did you count the flashes or use a code reader? Code 12 is a KOER only, it will not appear in the KOEO or CM checks. You will never get a code 93 on a manual transmission vehicle. I would not trust the results you got since 2 of the 3 supposedly KOEO codes are bogus.

As far as the KOER results go Code 21 will pop up if you did not warm up the engine before starting the tests. This code can also happen during the KOEO tests as well. Code 41 is most likely caused by the O2 sensor wire problem as Slip ford man stated above.

 

Sounds like you may also have the wrong computer in the truck. The computer may be out of Automatic Transmission Truck or Car.

 

I grounded the self test input and counted the check engine lights. Ill redo it today while im on break and see what I get. Ill make sure the engine is warm to. I did read the chiltons manuel but where am I supposed to go to WOT? IT said something about pressing the break and turning the steering wheel after it gives the codes? Is that right?

Thanks again Josh

 

Try this: Fuel Injection Technical Library » KOER Test

 

Allright Thanks!!!! Will repull them after the holidays! Thanks Josh

 

So I repulled the codes for the KOER test and codes 77, 52, and 21 went away.
I did get a new one though. Code 25-Knock not sensed during dynamic test. Ive done a search on here and on ford fuel injection.com but cant figure ot what it means or how to fix it. I am about to test my EGR

 

I get that sometimes...just get the motor hot and rerun the test

 

How hot does it need to be??? I let it idle for about 20 min before runnin the test so it was pretty warm.