ok so im new to fords i have owned chevys all my life (insert jokes here) but i came across a 94 f150 with the 300 6 and a 5 speed. the truck runs pretty good but it wont hold an adle sometimes. if i start it cold i have to hold the gas. and when its warm it wants to choke out sometimes i pulled the codes and got 12,11,21,15,12,51, as far as i can tell looks like coolant temp sensor, idle control, and maybe someone un hooked the battery. i checked the idle control motor getting 12 volts to it but it doesnt do anything. the temp sensor on the dash works. if anyone could point me in the right direction with this i would apperciate it. is there anything else i need to look at from what these codes are saying

 

How did you check for codes? Reader or paper-clip/read flash method? Ford start to transition to 3 digit codes in 1991. It is rare, but not impossible, to get two digit codes on a 1994 model.

Which test were you running when you got the codes? Key On/Engine Off (KOEO) or Key On/Engine Running (KOER). Your code list appears to be all over the board. We need some more clarification. It is highly suggested to start with the KOEO tests, which also includes a display of historical (Continuous Memory) codes. Then move onto the KOER once KOEO/CM are clear.

A prerequisite to running the KOEO or KOER tests is bringing the engine up to operating temperature. If not, you will trigger false ECT sens0r and possibly ACT/IAT sensor faults. Another thing to point out; Ford in their infinite wisdom requires the user to keep the clutch pedal depressed during the tests for the 4.9L equipped trucks. Otherwise you will trigger a false Neutral Safety Switch (NSS) code as well.

Do not confuse the dash temperature gauge sensor with the Engine Coolant Temperature (ECT) sensor which supplies the computer (PCM) with engine temperature information. They are two different sensors.

 

Reading between the lines.
My guess is you have a 121 code that is maybe a bad TPS.
Also the 512 says that the battery was maybe disconnected and that is why you got the memory keep alive code.

Also you need to address the IAC valve not working.

 

oh ok didnt know ford used three digit codes. well i checked koeo normal runnig temp did not have the clutch in though. checked it with a jumper wire/paper clip. these are the blinks im getting from start to fininsh and i did it 3 times to make sure i got it down right. 1,2,1,1,2,1,1,5,1,2,. thanks for the quick replys

 

It appears magic reading was correct, Code 121 TPS output too high or too low at closed throttle. Code 512 was from Continuous Memory, the key clue is the Separator code of 1 between the second 121 and the 512 code from CM.

You need to verify the TPS output. Use this for reference: Fuel Injection Technical Library » Throttle Position Sensor (TPS)

Very odd you did not get a code for a open NSS switch. You never know!

 

thanks for all the help. do u know which wire i need to probe to check the voltage the link above wouldnt open. is there a sticky on this site with a list of the three digit codes

 

Here is a list of the codes:
Fuel Injection Technical Library » 3 Digit Self-test Codes 111-171
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thanks for the info. well i tested the tps and it checked good both in voltage and resistance so i checked the iac and it was not moving at all and it was at .6 ohms so ireplaced it and no more problems. cel stays off. i guess the iac can throw a tps code.

 

No, the IAC cannot trigger a TPS code. What was the closed throttle TPS voltage?

 

.750 volts closed and fluctuated smoothly

 

Perhaps the TPS connection was corroded or otherwise compromised? Maybe the testing and replacing parts was enough to clear up the issue?

Re-run the KOEO tests. If it passes, you are good.

If not:

Then your next step is to verify that signal is getting back to the computer (PCM). Assuming Code 121 is displayed during the KOEO tests that means the signal at the computer is out of range.

Pin 46 is Signal Return, Pin 26 is VREF, Pin 47 is the TPS signal output. My money is on the wire leading to Pin 47.

 

ok drove the truck to work today and the problem is still there not nearly as bad but is there. has a slightly rough idle and sometimes coughs and sputters for a second while idleing. doesnt die anymor on cold start up and the cel is not coming on. i checked codes and i get 3 slow blinks pause 3 slow blinks long pause 1 blink long pause 5 fast blinks pause 1 blink pause 2 fast blinks repeats that one more tim and thats it. so correct me if im wrong but i think that is 111 system pass and 512 kam error from when the bone head i bought it from unhooked the battery.

so now i want to check timing to veryfiy it is correct since the other guy put new cap rotor wirs and plugs, now i know on obd1 chevys there is an est wire that needs to be unplugged to adjust base timing is ford using something similar or do i just adjust the dizzy.

 

If you replace a sensor you need to unhook the battery for about 15 minutes so the computer can relearn the the new sensor. This will also set the 512 code in CM.

Then to clear the 512 code, ground the STI wire like you were going to run the KOEO electrical test, turn on the key and when the MIL on the cluster starts to flash remove the ground from the STI wire and the codes will be cleared.

To set the timing you need to remove the SPOUT shorting bar (jumper), sand the timing mark, mark the 10 deg BTDC mark with paint or some white or yellow marker.
1. Hook up the timing light to #1 plug wire (the front plug on the 300 or front passenger side on an 8 cyl).
2. Loosen the distributor hold down bolt.
3. Start and warm up the engine.
4. Turn the distributor until the pointer is aligned with the 10*BTDC mark.
5. Tighten the hold down bolt.
6. Recheck the timing to make sure it is still at 10* BTDC.
7. Reinstall the SPOUT shorting bar.
8. Check the timing to make sure it has moved to about 10-20* BTDC.
9. If it has then shut off the engine and remove the timing light.
10. You are done.
11. If the timing did not move to about 10-20* BTDC and is still at 10* BTDC then you have a problem with the wiring, ICM, PCM or the SPOUT shorting bar.

The SPOUT shoring bar (should be here for the OP in this thread):


OR for older locations:


OR here for older V-8 engines:

/

 

Great advice as always Bill!

 

ok i have not been able to check ignition timing yet will do that this weekend but now the truck has a new symptom when im going dow the road if i push in the clutch to come to a stop the engine stays stuck at a high rpm im guessing around 2 to 3k. if i bring it down with the clutch it will stay down untill i start going again. shifting threw gears it doesnt come down it almost like a bad vacum leak but but it doesnt do it all the time. just when im moving. i can be stopped and rev it and it will come back down.ive checked throttle linkege for binding but have found nothing. once again i checked codes and all i get is 111 and 512. i saw that someone said i can check koer codes all i have checked is koeo. didnt know i could safley start the engine in diagnostic mode.so all i do is put the jumper in and start to read the codes? if anyone has run into this problem before please advice. i will get back with timing asap