Need pro advice on TFI problem??

The first two codes are key:
98: Hard Fault is Present (reason why KOER self-test is aborted)

I would clear codes and re-do a KOEO, if code 98 reappears with other codes, you need to fix the codes accompanying code 98 before attempting a KOER self-test or any other modification to the system. My 2¢.

Code 14 - Ignition pickup (PIP) was erratic – the hall effect sensor in the distributor is failing. Bad sensor, bad wiring, dirty contacts. You have to press the distributor gear off the shaft to replace the sensor. The pip signal is used for ignition timing and fuel injector timing.

CODE: 31 (KOEO) - EVP circuit below minimum voltage. Vref (5 volt reference voltage supplied by the computer) missing or broken wire or bad connection in circuit. Use a DVM to check for 5 volts on the orange/white wire. If it is missing, look for +5 volts at the orange/white wire on the TPS or MAP sensor located on the firewall near the center of the car. Use the black/white wire for the ground for the DVM.
With the sensor removed from the EGR and still connected, press the plunger and watch the voltage change on the brown/lt green wire. Pull the passenger side kick panel and measure the voltage at the computer. You will need to remove the plastic cover over the wires and probe them from the backside. A safety pin may prove very useful for this task. Use pin 27, EVR input (brown/lt green wire) and pin 46, signal ground (black/white wire) to measure the voltage. The orange/white wire is Vref and should always be 5 volts -/+ .25 volt. Be sure to measure Vref at the EGR sensor to rule out any broken wires or bad connections.

Code 51 Engine Coolant Temperature (ECT) sensor signal is/was too high - Possible bad ECT sensor, or wiring.
Use Pin 46 on the computer for ground for both ECT & ACT to get most accurate readings.

Pin 7 on the computer - ECT signal in. at 176 degrees F it should be .80 volts

Voltages may be measured across the ECT by probing the connector from the rear. Use care in doing it so that you don't damage the wiring or connector.

Here's the table :

68 degrees F = 3.02 v
86 degrees F = 2.62 v
104 degrees F = 2.16 v
122 degrees F = 1.72 v
140 degrees F = 1.35 v
158 degrees F = 1.04 v
176 degrees F = .80 v
194 degrees F = .61

Note that all resistance tests must be done with power off. Measuring resistance with a circuit powered on will give false readings and possibly damage the meter.

Ohms measures at the computer with the computer disconnected, or at the sensor with the sensor disconnected.
50 degrees F = 58.75 K ohms
68 degrees F = 37.30 K ohms
86 degrees F = 27.27 K ohms
104 degrees F = 16.15 K ohms
122 degrees F = 10.97 K ohms
140 degrees F = 7.60 K ohms
158 degrees F = 5.37 K ohms
176 degrees F = 3.84 K ohms
194 degrees F = 2.80 K ohms

Code 54 – ACT sensor out of range. Broken or damaged wiring, bad ACT sensor. Note that that if the outside air temp is below 50 degrees F that the test for the ACT can be in error.

Check the resistance of the black/white wire to battery ground. If it is less than 1 ohm, it is good. If it is more than 1 ohm, the black/white wire has bad connections or a broken wire. Always take resistance measurements with the circuit powered off.

Then check the resistance of the ACT sender located in the #5 intake runner on most 5.0 stangs.

ACT & ECT test data:

The ACT & ECT have the same thermistor, so the table values are the same

Pin 7 on the computer - ECT signal in. at 176 degrees F it should be .80 volts

Pin 25 on the computer - ACT signal in. at 50 degrees F it should be 3.5 volts. It is a good number if the ACT is mounted in the inlet airbox. If it is mounted in the lower intake manifold, the voltage readings will be lower because of the heat transfer. Here's the table :

68 degrees F = 3.02 v
86 degrees F = 2.62 v
104 degrees F = 2.16 v
122 degrees F = 1.72 v
140 degrees F = 1.35 v
158 degrees F = 1.04 v
176 degrees F = .80 v
194 degrees F = .61

Ohms measures at the computer with the computer disconnected, or at the sensor with the sensor disconnected.
50 degrees F = 58.75 K ohms
68 degrees F = 37.30 K ohms
86 degrees F = 27.27 K ohms
104 degrees F = 16.15 K ohms
122 degrees F = 10.97 K ohms
140 degrees F = 7.60 K ohms
158 degrees F = 5.37 K ohms
176 degrees F = 3.84 K ohms
194 degrees F = 2.80 K ohms

Code 98 - basic computer internal tests not passed before it started processing the request to dump codes. Do a Key On Engine Off test before starting the engine. Wait until you see the 11 flash before pressing any buttons if you have a hand operated scanner. The computer is operating in Limp mode, so fix any codes it dumps prior to doing anything else.

In your case, fix code 14 first before attempting to fix any of the other problems.

bdollarbill said:

Jrichker
Would putting the MSD 6al box & the pro billet with centrifical adavnce take the pip out of the picture? I still need to id the other codes too. On my car I have a brass tube blocked off on the #5 intake runner. I didnt do it but previous owner had it blocked off. Do you have a picture of the ACT sensor on the #5 runner so I can see if thats part of my problem.

Click to expand...

You didnt ask me, but I was reading past this thread...........

The PIP is still needed no matter what aftermarket piggyback ignition box you run. The PIP supplies base spark and ignition timing to the computer - kinda important.
It can be worth removing the dizzy cap and rotor and seeing what kind of slop the dizzy shaft has, since any run-out can affect the PIP window readings. FWIW, good or bad, I have sprayed electrical contact cleaner on the PIP (it is super dusty where I live) and it seemed to help a burp I was having.

Here is a link to a pic of the engine - it might be useful in identifying miscellaneous things you find that dont look right.

Good luck.

Bdollarbill;

Check the following:

1. Clear codes, don't start or crank the engine
2. Do a KOEO self-test
3. Check the On Demand codes you get (and the Continous Memory, of course) and LUK.

Reasoning behind the suggestion above is, PIP signal will be taken out of the picture. Since PIP is generated when the engine is turning, the system won't check for it, allowing the id of any other real "hard faults" detected by the system, which I think are the ACT and ECT crt. failures.

BTW, can't get rid of the PIP signal, as HISSIN50 explained....how would the system calculate and set timing advance? GL