3 codes driving me nuts

[holyford86]

I have had KOER codes 12,74,and 77, I can not get rid of them. first #12, The computer says that the idle is too low, It idles right at 850 rpm, tps voltage is 0.948 volts at idle, TPS is new (flat voltage in center of travel with the old one). #74 I am pressing the brake after the engine id is received, the brake lights are coming on as well, there is little resistance across the switch terminals when the brake is pressed. Would having LED tails cause this? #77 I am pressing the gas to the floor when my code reader tells me to (blue point YA3140). I checked to see if the throttle goes to WOT with the gas pushed to the floor, it does, is there a way to tell when to snap the throttle, either by waiting a certain amount of time or listening for the engine to make a certain sound? This is on my '86 so there is no check engine light to watch for blinks...

 

[piotrsko]

I could be wrong, but I thought the TPS needed to see .6 +.3 -0 volts so i think you're a bit high. You might want to clean out the IAC valve in the pass side of the manifold.

the BOO check is ONLY if you have a 2 liter engine with a brake switch.

to run the WOT check I usually need a person watching the reader. On mine, you get a 6 then wait a bit then a 10. at 10, You tromp the throttle only ALL The WAY to the floor and immediately let up. I'm guessing you exceed the couple of seconds the computer gives you by tromping the brakes.

you also might want to erase the codes, (btdt looong story)

 

[holyford86]

I could be wrong, but I thought the TPS needed to see .6 +.3 -0 volts so i think you're a bit high. You might want to clean out the IAC valve in the pass side of the manifold.

the BOO check is ONLY if you have a 2 liter engine with a brake switch.

to run the WOT check I usually need a person watching the reader. On mine, you get a 6 then wait a bit then a 10. at 10, You tromp the throttle only ALL The WAY to the floor and immediately let up. I'm guessing you exceed the couple of seconds the computer gives you by tromping the brakes.

you also might want to erase the codes, (btdt looong story)

I have always thought that the voltage from the center wire of the TPS should be ~.9 volts.

No matter what scanner I have used it has always asked me to press the brake, whether it be 2.3, 2.9, or 4.0

I can not see a light blinking when I use this reader it is a universal code reader that works with Chrysler, Ford, and GM OBD1 and also does OBD2. When it tells you to do it is the only indication you have of anything since I have an 86 with no CEL to watch for blinks, I may add one sooner or later.

When the KOER test is running the lowest the idle goes is about 1100 rpm but in normal running without the test active the idle is perfect right at 850 rpm. IAC is 8 months old and is a ford part, not a aftermarket pile of crap (been there).

codes were erased 2 days before when I did a test and got these three codes plus a code for TPS out of range (voltage leveled out in center of range). I verified what the voltage was before and after swapping the TPS and it was within a few hundreths of a volt different with no adjustments being made to the TPS adjustment screw.

 

[holyford86]

ran tests again, got rid of the code 77, scanner was telling me to goose throttle at the wrong time... Still have the other two though, checked for vac leaks as well and found nothing...

 

[IMenriched]

ran tests again, got rid of the code 77, scanner was telling me to goose throttle at the wrong time... Still have the other two though, checked for vac leaks as well and found nothing...

Do you have Cruse control??

 

[holyford86]

Do you have Cruse control??

nope, had an aftermarket unit on there for a while but I removed it recently

 

[IMenriched]

nope, had an aftermarket unit on there for a while but I removed it recently

On my 86 w/ factory CC...there is a vacuum switch on the brake pedal, to disengage the CC with a tap on the brakes...just wondering if that is still there, and or, leaking vacuum pressure a wee bit??

or have you disconnected that already? just tossing the thought out there