Thanks to the rain I just got around to re installing the computer, only change is that the random flashing check engine light now stays off, still an obvious miss though, there's also a second or so hesitation when hitting the go pedal, I'm lost at this moment, guess I'll pay someone to trace the wiring and check for brakes? I'm not doing it!
Odd Firing Problem
- Thread starter dcurtis
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mikestang63
SN Certified Technician
disconnect the S&P shakers- often the pins need to be looked at and tweaked so they make a better connection. Then put some dielectric grease into each connector and reconnect them. If you have the TSB installed S&P extension harness- remove it as they just cause another set of connectors that cause problems.
Those are one of the first thing I removed when I got the car, on a side note I had it running today and gave each wire from the connectors to the engine a tug, and when I jiggled the green wire which goes to the act sensor I believe? The engine started acting funny, had a friend over and he googled it and said it could cause spuratic timing? Also have to floor the throttle now to get it to start?
mikestang63
SN Certified Technician
Press the throttle to the floor & try starting it. If it starts, if this is your problem, the ECT or its wiring is at fault..
See the graphic for the 10 pin connector circuit layout.
It is the ECT (Engine Coolant Temperature) sensor in picture #6. It is the one you need to check.
The ACT (Air Charge Temperature) sensor lives in the #5 intake runner on the driver's side...
Code 51 Engine Coolant Temperature (ECT) sensor signal is/was too high -
Possible bad ECT sensor, or wiring. Possible missing signal ground – black/wire wire broken or bad connection. With the power off, measure the resistance between the black/white wire and battery ground. You should see less than 1 ohm. Check the same black /white wire on the TPS and MAP sensor. More than 1 ohm there and the wire is probably broken in the harness between the engine and the computer. The 10 pin connectors pass the black/white wire back to the computer, and can cause problems.
The ECT sensor is not the same as the temp sender for the temp gauge. It is located in the front part of the tubing that feeds coolant to the heater. It has two wires connected to it.
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.
50 degrees F = 3.52 v
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
212 degrees F = .47 v
230 degrees F = .36 v
248 degrees F = .28 v
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
212 degrees F = 2.07 K ohms
230 degrees F = 1.55 K ohms
248 degrees F = 1.18 k ohms
Diagram courtesy of Tmoss & Stang&2birds
See the following website for some help from Tmoss (diagram designer) & Stang&2Birds (website host) for help on 88-95 wiring http://www.veryuseful.com/mustang/tech/engine/
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif
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