Hey yall! Got a question for ya, thanks in advance for your help everyone.

1990 f-250 5.8 5 speed manual

The question is what does it mean if i have both code 12 and 13 on the KOER test?

I only get those two codes on the running test. Do not get it on koeo or cm

From the code list i found on the ranger station this is what they are:

12 - Idle Speed Control motor or Air Bypass not controlling idle properly (generally idle too low) - ISC

13 - (R) Idle Speed Control motor or Air Bypass not controlling idle properly (generally idle too high)

Troublecodes.net says this:

12 RPM Not Within Self Test Upper Limit
13 RPM Not Within Self Test Lower Limit/DC Motor did not move



Thanks!

 

This means that the computer can not control the idle air, could be vacuum or idle air control it's self. There could be a number of problems wiring, plug, idle air control, vacuum leak that come to mind. With EOER the self test the computer will command the idle air motor to move the pineal in to reduce idle and out to increase idle. If there is no change between command and RPM it will set a code. Could just be carbon that needs to be cleaned

 

Thanks man I appreciate it. If it is carbon where would the buildup be that needs to be cleaned? Im still a newb so not sure on the locations of these parts. Thanks!

 

It would be around the hole of the of the IAC and the pintail. Some time you get a chunk stuck behind the pintail. Don't get any cleaner in the iac motor, just clean the hole and the pintail. Don't pull on the pintail rod or the calibration will be out. You can hook a volt meter to the back of the plug. Do your EOER test and watch the voltage change, if there is no voltage you have a wiring problem. I use a vantage scope to graph the movement, but a meter will do the same. You can also introduce a vacuum leak the iac should try to control the high idle again you will see this on your meter. If the voltage changes but the iac is not responding replace it. This way you are sure the iac is no good, better then throwing money at the problem. You can also do ohm test to see if the motor has a open circuit. Is your idle high when running you could also have a vacuum leak that the iac can not correct. Or running rich, injector or other problem that the iac fully open can not correct.

 

Ill check that out thanks! Instead of running rich, I do have a lean problem. During KOER test, in addition to the 12 and 13 codes, I have codes:

41 Heated Oxygen Sensor (HO2S) circuit indicates system lean (rear HO2S)

33 Exhaust Gas Recirculation (EGR) valve opening not detected

I have replaced the o2 sensor with a good bosch unit, cleared codes, and 41 came back.

Tested fuel pressure, was at 73 psi at idle , replaced regulator, now at 33 at idle.

When I did the spark plugs, All 8 were whiteish instead of the golden brown
so im thinking it really is lean instead of a error? I was expecting it to be way rich because of the high fuel pressure or am I not thinking of something?

Thanks!

 

In your case I think you have confirmed what the computer is telling you with the white plugs.. the motor was running lean despite having double the fuel pressure it should. The computer can and does compensate for things like this so that suggests your injectors are all still good and the computer has control over them, but something else outside computer control is causing the system to run excessively lean. That could be an exhaust system leak or a problem with the air injection system that is either putting too much or too little air into the exhaust upstream of the O2 when it is in closed loop, or it could just have been a tired O2 sensor that was still switching but had drifted off calibration.

 

Thanks man! I replaced the o2 sensor, cleared the codes, and the lean code 41 came back so im thinking it wasnt just the o2 sensor?

Do you have some pictures or diagrams or the air injection system? Not sure where the parts for this are located so I can start checkin it all out. Thanks again

 

Also could EGR issues cause a lean condition?

 

Your lean code for o2 sensor could be a defective cat. If your plugs are whitish could be lean condition. Write down your code clear them and drive it see what comes up before you replace any parts. This will give you a good indication what's going on. Your EGR could be plugged passage or bad EGR. Pull up on the EGR diaphragm see if the truck wants to stall if not passages are plugged. Put vacuum gauge on line going to EGR KOER test see if reads any vacuum. If I were you I would start check for vacuum leaks and fix EGR first then go from there. Check pintail on EGR for crap. If EGR is not working can set phantom codes. What size engine are you working on and year?

 

Replaced o2 sensor, cleared codes, 41 lean condition code came back. I changed plugs, all 8 plugs are white so it actually is running lean, not just code.
Can EGR issues cause it to run lean? 1990 f-250 5.8. Thanks for all the help and info!

 

Replaced o2 sensor, cleared codes, 41 lean condition code came back. I changed plugs, all 8 plugs are white so it actually is running lean, not just code.
Can EGR issues cause it to run lean? 1990 f-250 5.8. Thanks for all the help and info!

 

oops sorry for double post

 

Hang on if this is a 1990 it's OBD I the heated O2 came out in OBD II 1994 to 1995. Your o2 sensor is it a one wire? Is the original motor?

 

4 wire heated and im pretty sure it is original engine yes

 

Sorry brain fart, it did have heater circuit. I would start with basics mist water around intake and vacuum lines. The EGR allowed exhaust gas into the combustion chamber to reduce NOX by lowering combustion temp. This will cause a richer mixture in the cylinder. Check vacuum leaks, EGR for vacuum leaks and blockage. You can buy pads air injection by removing belt see if that make a difference,