Car Running Odd/poor

whtbullitt

Active User
May 24, 2015
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I just had a stuck injector (after sitting all winter) so I changed out the injectors for brand new ones, replaced the spark plugs, fuel filter, o2 sensors and new oil and filter. About 10 quarts was drained from the pan due to all the gas. It ran super strong the first 5 minutes or so then it completely lost all power, I floored it and it went nowhere, the tach didn't move. I coasted to the side of the road and it shut off. I was able to start it but I had to give it some gas to get it going. Again, it ran awesome for about 1 minute and did the same thing, this time I coasted into my driveway. Shut it off, fired it back up immediately and again, it revved great and I did a nice smokey brake torque burnout but I didn't try taking it on the road. The check engine light did come on on the way home but went off and backfired once or twice.
The car is a 1993 GT with 52,000 miles with no emissions gear, H/C/I... all the normal goodies and has a custom tune by JLP. Voltage, Oil and temp gauges were all within a good range. I think that is all the relevant info I can think of.
I will pull codes tonight but was hoping someone could help me out some.

Thanks!
 
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Code 18 is open SPOUT circuit, and code 29 is no signal from vehicle speed sensor.

Set timing and forget to put spout in by any chance?

Timing wasn't touched and is at 10 degrees. The only things that I can recall having done in the past 3 years ( I dont drive the car much at all) were new ignition module, coil and the dyno tune. Would a faulty ignition module or coil cause any of these symptoms or a possible loose/bad connection on the ECU or harness?
 
Timing wasn't touched and is at 10 degrees. The only things that I can recall having done in the past 3 years ( I dont drive the car much at all) were new ignition module, coil and the dyno tune. Would a faulty ignition module or coil cause any of these symptoms or a possible loose/bad connection on the ECU or harness?
The code18 falls in that category...

Code 18 - SPOUT out or wiring fault - look for short to ground in SPOUT wiring going
back to the computer. Possible bad TFI or defective 22 K resistor in the IDM wiring

Use a timing light to check the timing: remove the SPOUT and observe that the timing retards at least 4 degrees. Put the SPOUT back in place and observe that the spark advances at least 4 degrees.
This code can disable spark advance and reduce power and fuel economy.

Remove the passenger side kick panel and disconnect the computer connector.
There is a 10 MM bolt that holds it in place.
Disconnect the TFI module connector from the TFI and the measure the resistance between the yellow/lt green wire and ground.
You should see greater than 100 K (100000) ohms.
Check the resistance from Pin 4 on the computer connector (dark green/yellow) and the dark green/yellow wire on the TFI connector. You should see 20-24 K Ohms (20,000-24,0000 ohms).


Resistor location: A big thanks to liljoe07 for this information:

Check over by the brake booster. Its not in the harness on the TFI, its on the main part of the harness over by the plugs that connect to the dash harness. About 6" or so from that, going back toward the EEC.

If I remember right, the resistor is covered in a shrink tubing that is sealed to the wires. So, you wont be able see any markings. The shrink tubing is labeled though. It's a 22kohm 1/2 watt resistor.

Here is the location.

20150328_105525-jpg.532446.jpg


Next measure the resistance between the yellow/lt green wire on the TFI module connector and Pin 36 on the computer connector. With the SPOUT plug in place, you should see less than 2 ohms.

The following is a view from the computer side of the computer connector.
eec-iv-computer-connector-for-5-0-mustang-gif.88243.gif


This diagram is the wire side of the computer connector.
a9x-series-computer-connector-wire-side-view-gif.71316.gif


Diagram courtesy of Tmoss & Stang&2birds

88-91_5.0_EEC_Wiring_Diagram.gif
 
I always see threads like this end with no resolution or followup from the thread starter so I wanted to give an update and hopefully it helps someone in the future. Thanks to all who replied with help.

In my case - I swapped in another ecu and it ran great so I sent out my ecu to get repaired and found out the power supply and voltage regulators were both shot. Hopefully, knock on wood, my car will continue running the way it should. I also recommend ECU Exchange off of ebay if you need a ecu repaired.
 
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