Electrical 90’ lx dies while driving or idling randomly please help

Black_Mare · Dec 22, 2018

Hey guys, need help please, been bangin my head over this issue for the past week, the issue is the car randomly dies, loses spark, all accessories will stay on, tach drops to 0, if I turn the key off and back on it will turn back on most the time, sometimes I have to cycle the key twice 3 times even, I have replaced the following:
New motorcraft tfi
New motorcraft pip
New msd coil
New starter relay
New ignition switch
New cap and rotor
New fuel pump relay
New eec relay
New msd wire from coil to dizzy

When the car dies it doesn’t have spark, but I got 12 volts to the coil, 12 volts at ignition switch, 12 volts at injectors, 12 volts at the plug for the tfi, I do not have a noid light to test pip but again I have 12 volts at injectors and the car will not start even with spout removed, next I tested the tfi by bridge the 2 wires at the coil with a test light and cranking, the test light does not flash, which means the tfi is faulty? Car was working just fine, I put a msd coil and advanced the timing and it started this mess, but it ran better, ground from engine to battery is good, battery to car, head to fire wall, I’m I missing any? I’ve put the stock coil back on and still does it hahaha I’m about to pull my hair out someone please help

Black_Mare · Dec 22, 2018

Also when the car dies if I unplug the tfi and plug it back in the car will start, when I put the new tfi the issue got better for a day then got worse and worse and worse, car is damn near undrivable how much it shuts off abruptly

Black_Mare · Dec 23, 2018

Anybody?

Dan02gt · Dec 23, 2018

Sounds like you have covered alot. How do your grounds look? Especially the one from the battery to the computer (the one that's grounded to the fender too)

I noticed that while working near the computer on mine it would die it I touched the harness near the computer connector. What I found was that the dedicated power and ground barrel connectors were loose on the computer pins. I depenned the computer connector and tightened the barrel connectors.

If you haven't already check and tighten the connections in the 10 pin salt and pepper connectors too.

DSB88GT · Dec 23, 2018

First of all, you need to pull your codes. That will narrow it down for you. The TFI's are hit and miss, even the Motorcraft ones when new. It's very possible your new TFI is bad.

Black_Mare · Dec 23, 2018

Hey guys thanks for reply, there are no codes, it’s getting worse and worse car won’t idle for more then a minute or 2 shuts off no spark, turn key off and back on fires right up idles for 2 minutes dies no spark key off on fires right up on and on and on

Black_Mare · Dec 23, 2018

Actually it’s throwing code 18, spout circuit open?

General karthief · Dec 23, 2018

Go through the cranks but no start checklist in the tech/how to forums.
go through it step by step, don't skip around.

Black_Mare · Dec 23, 2018

Well when the car dies if I jump the plug at the coil with a test light and crank the test light does not flash, which means the tfi is bad, I just bought this tfi brand new from ford dealer, I’m just making sure it’s not something else until I get a new one in, and make sure there’s nothing killing the tfi’s On the car, code 18 from what I’ve read allot of people say there’s a short somewhere, I have ran through all the wires I have all my grounds and spare grounds, I have tested everything I possibly can with all the different check lists available for fox body’s diagnostics, I keep concluding my tfi started going out then the new one was faulty out the box, a new new one is on the way but won’t be here until the day after Xmas, so I guess just enjoy the holidays and try to stay away from the garage as much as possible

General karthief · Dec 23, 2018

Ohhh no! I'm going to spend as much time in my garage as possible!
It's almost done!

jrichker · Dec 23, 2018

Black_Mare said:
Actually it’s throwing code 18, spout circuit open?

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:

liljoe07 said:
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.

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.

This diagram is the wire side of the computer connector.

Diagram courtesy of Tmoss & Stang&2birds

Black_Mare · Dec 23, 2018

Ok that 22k resistor by the brake booster, I’m getting power on one side of it and none on the other, is that my problem?

Black_Mare · Dec 23, 2018

So I find the 2 wires from ac melted touching each other, I take apart, start the car, idles for a while, longer then usual, thought I figured it out, dies, check code I get code 15, no more code 18, pull pin turn off car then restart, idles for a bit, dies, check code code 18 no code 15, what does this mean

Black_Mare · Dec 27, 2018

Tfi from ford was bad out the box, for anyone with similar issues, I put a parts store tfi duralast brand and haven’t had issues since

Electrical 90’ lx dies while driving or idling randomly please help

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Dan02gt

mazing how much gas smell came from that tiny hole

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wonder how much it would cost to ship you a pair

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wonder how much it would cost to ship you a pair

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Electrical 90’ lx dies while driving or idling randomly please help

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