all are from KOER 89 f150 302 with A0D 2wd.

12: cannot control RPM during self-test high RPM check.

44: thermactor AIS sys system inoperative right side. (this should be a big DUH since the previous owner took the pump off)

13: cannot control RPM during self test Low RPM check

25: dyn response test knkock sensor not detected

great. now what? i HAD this thing running fine after i swapped out the wires and plugs. it was idling alot better as it always used to idle high as the sky. then i went to check for KOER codes and grabbed the couple in the engine compartment then the truck died. turns out one of the leads in the fuel pump relay corroded and broke off starving the fuel pump of power to run.

i have since replaced that terminal with a new one and it started right up. and the codes above is what i got this time. please note that it now idling where it used to originally, high as the moon.

 

Sounds like a vacuum leak to me. Did you floor the gas pedal when you were supposed to during the KOER test? That would explain your code 25.

 

i did. before the terminal crapped out on me in the fuel relay, the idle was fine. i had found a vacuum line that broke off when i was hunting for that elusive vacuum leak. so i just pulled that line off of the intake manifold and plugged up the hole. this was when the idle was fine before i tried scanning for DTC's.

now after i spliced a new terminal to the fuel relay yesterday, i also popped on a new vacuum line to the one that wore out, and now it's idling high. the vacuum line runs over from the manifold to the HVAC box on the passengerside of the compartment.

 

If you floored it when you were supposed to, then the ECM is telling you that you need a new knock sensor, but I'd fix the idle first and retest before spending any money.

Disconnect and plug your "new" vacuum line at the manifold. If the idle returns to normal, you have a vacuum leak somewhere in your HVAC controls. Otherwise check your fuel pressure. Simply replacing the fuel pump relay won't have any affect on idle speed, unless the there is another fault in your fuel system, which is highly unlikely.

 

ok, so i bought a hand operated vacuum pump (the one i had died on me). i popped off the vacuum end at the manifold and stuck the pump on that end. pumped it a couple times and the needle sat at 0. pumped it faster and the needle drops pretty quick. it was not holding any vacuum. so the leak is in the HVAC system. i plugged the nipple on the manifold for now like i did before.

i haven't started the truck yet as i didn't have time to.

now hopfully it's easy to find that leak in there otherwise my heater and A/C won't work at all..lol.

thanks.

 

Have someone blow smoke through the line, while you look for it inside the truck. That will help you find the problem.

 

ok, so i guess it's not really the HVAC that's leaking. cuz it still idles high even when i did plug that nipple on the mani with it running. when i stuck a vac pump and gauge on the end of the HVAC it still kinda holds vacuum but it drops. slow or fast is in the eye of the beholder...

so i pulled other lines; brake booster and the T that feeds the cruise solenoid and the EVAP can (i hope that's what it is.)

i plugged the brake booster nipple at the mani and no change in idle. i tested vacuum hold of that line itself and there are no leaks. then i hooked up the line to the booster and tested the entire assembly. holds.

next vac line; i pulled it with the motor running and the motor starts to stumble and tries to die. i try plugging that nipple at the mani with my thumb while the motor is still running and it dies. i plug it back in and now it's having trouble starting. it's also having trouble staying running.

i tested the vac at the end of that line still hooked up to the cruise and EVAP and there is no vacuum. i test the feed line itself, it's good. i test it at the T. no good. i break off the T and test the line and the cruise solendoid. it holds vacuum. then i test the other line at the T. no good. i test the line itself and it's good. so i guess it's the EVAP canister (is that what that is? its the can sitting below the drivers-side headlamp down at the bottom.) it looks pretty old and rusty...

but how does thie affect the motor from stalling out/stumbling/hard starting?

i'm still getting pretty much the same codes as before

12: cannot control RPM during self-test high RPM check.

44: thermactor AIS sys system inoperative right side. (this should be a big DUH since the previous owner took the pump off)

13: cannot control RPM during self test Low RPM check

oh yeah, the truck died right when the scanner got done scanning the codes too.

 

My truck is the same as yours.

1) the white defrost vacuum hose was bad. Mice also chewed thru other hoses that I patched.

2) the gasket between the upper and lower halves of the intake manifold was bad. I fixed that.

3) I cleaned the IAC and replaced the temp sensor.

Now the ol' truck idles at 600-650rpm!

To help locate a vacuum leak, spray brake cleaner on suspect areas with the engine running. You should hear a slight "stumbling".

-Lance

 

so replaced the vacuum resevoir. it was rusted pretty bad that it pretty much crumbled to peices. got lucky and found some in the junk yards. got luckier as out of all the ones i found at the yards only 1 was still good; as all others were alot worse than my original can. tested it at the yards with my vacuum pump and it held vacuum!

popped it into the truck and hooked up a vac pump and vacuumed out the can and the speed control (cruise control) before the check valves. hooked the the main line back to the vac source (vac manifold on the intake manifold) started it up and it warmed up but still idled high.

there is a solenoid bolted just below and in front of the ignition coil that has 2 vac lines going to it. one line is hooked up to the vac source and the other runs off to somewhere i forgot. i tested this assembly and it's not holding vac. what is this solenoid? and is it supposed to hold vac?

 

Just out of curiosity, have you tried turning down the idle screw?

 

everyone and all the books tell me not to. so i haven't.

 

Generally speaking, you shouldn't, but I didn't know if you or someone else might have adjusted it previously.