90-99 Ignition Gurus Please Chime In.......

IN2DEEP

New Member
Jan 1, 2004
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I've been chasing some gremlins trying to find the thing that's killing my ignition modules at a rapid rate. I didn't want to add to my previous post as I found an answer of sorts.

Over the last year I did an engine swap in my Jeep CJ5. The 5.0 engine and the EFI system are from a 1990 Crown vic. And I swapped in the 5.0 engine from a 1999 Mountaineer. After the swap, I was experiencing ignition module failures pretty often.

One thing I've recently determined is that there is more to the engine swap than just a new firing order. Evidently all Mountaineers had the HO engine. I had to re-pin the injector harness to get the injectors to fire correctly. And I've replaced the ECM with an old one I had on the shelf. The engine has responded nicely, and now will fire and run!! I've driven it a few times and all seems well. But I don't know how to have confidence in the Jeep as she's let me down before.

So the questions:
Would having the injectors firing order incorrect cause premature ignition module death? How?
Would this set up kill an ECM?

I understand the firing order issues on the distributor/mechanical side of things. But not really sure what's happening on the ignition side of things. Honestly, I don't know how the engine ran as well as it did initially after the swap at all. It seems like the gas and spark would be way out of line. And I shouldn't have been able to start it at all (four injectors firing at the wrong time).

I'm very surprised that the ECM failed, as it's a new unit that has seen very little road time. I only replaced it because I had the old one on the shelf and it was a pretty painless swap. But it paid big dividends because it got me back on the good side of things.

Thanks for everybody's help.
~Drew
 
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Mustang5L5

Put lubricant all over the balls
Mod Dude
Feb 18, 2001
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When the ecm fails, are you able to identify a component on the board that failed? Might help clue us in on what is getting overloaded and failing?

An EDIS8 conversion might be worth looking into, but might require an A9L and tuner software to make it work. Upside no more TFI
 

IN2DEEP

New Member
Jan 1, 2004
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I opened the ECM and hoped to see a resistor or something burned or bloated. But it looked 100% fine........
 

Mustang5L5

Put lubricant all over the balls
Mod Dude
Feb 18, 2001
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Massachusetts
You are using the gray style TFI with wiring setup to match correct?

IMG_4633.GIF


If correct, I'd start testing voltages from the eec to the TFI and looking up published specs on what they should be (I don't have handy) and confirming they are in range. For instance, Run power in might call for 5v, but you are sending it 12v somehow.

I don't have the true values for these however, but the fact you keep burning them up makes me think it's getting too much power on one of the wires. These TFIs aren't that fragile, in still on my original 1988 TFI in my car.
 

IN2DEEP

New Member
Jan 1, 2004
25
1
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Yes, I am using the grey module (second from the top). I've moved it to the fender. I will check the voltages.
 

jrichker

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Mar 10, 2000
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You are using the gray style TFI with wiring setup to match correct?

IMG_4633.GIF


If correct, I'd start testing voltages from the eec to the TFI and looking up published specs on what they should be (I don't have handy) and confirming they are in range. For instance, Run power in might call for 5v, but you are sending it 12v somehow.

I don't have the true values for these however, but the fact you keep burning them up makes me think it's getting too much power on one of the wires. These TFIs aren't that fragile, in still on my original 1988 TFI in my car.

The catch here is that if the TFI pin#4 start signal is powered up, it increases the dwell time, which increases the current flow through the TFI module. On fox body Mustangs, the starter solenoid red/blue trigger wire is connected to the TFI pin #4

The following are diagrams courtesy of Tmoss & Stang&2birds

Complete computer, actuator & sensor wiring diagram for 88-90 Mass Air Mustangs
88-91_5.0_EEC_Wiring_Diagram.gif



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/ Everyone should bookmark this site.



TFI module wiring for 94-95 Mustang GT
http://www.veryuseful.com/mustang/tech/engine/images/Mustang-94-95-IgnitionControlModule.gif

Complete computer, actuator & sensor wiring diagram for 91-93 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/91-93_5.0_EEC_Wiring_Diagram.gif

Complete computer, actuator & sensor wiring diagram for 88-90 Mass Air Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/88-91_5.0_EEC_Wiring_Diagram.gif

Ignition switch wiring
http://www.veryuseful.com/mustang/tech/engine/images/IgnitionSwitchWiring.gif

Fuel, alternator, A/C and ignition wiring
http://www.veryuseful.com/mustang/tech/engine/images/fuel-alt-links-ign-ac.gif

O2 sensor wiring harness
http://www.veryuseful.com/mustang/tech/engine/images/mustangO2Harness.gif

Vacuum diagram 89-93 Mustangs
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxFordVacuumDiagram.jpg

HVAC vacuum diagram
http://www.veryuseful.com/mustang/tech/engine/images/Mustang_AC_heat_vacuum_controls.gif

TFI module differences & pin out
http://www.veryuseful.com/mustang/tech/engine/images/TFI_5.0_comparison.gif

Fuse box layout
http://www.veryuseful.com/mustang/tech/engine/images/MustangFuseBox.gif

Mustang 5.0 Lights and Radio schematic, by TMoss:
http://www.veryuseful.com/mustang/tech/engine/images/mustangFoxLights-Radio_diag.gif

87-92 power window wiring
http://www.veryuseful.com/mustang/tech/engine/images/mustang87-92 PowerWindowWiring.gif

93 power window wiring
http://www.veryuseful.com/mustang/tech/engine/images/mustang93PowerWindows.gif

T5 Cutaway showing T5 internal parts
http://www.veryuseful.com/mustang/tech/engine/images/5_Speed_Cutaway_Illustrated.jpg

Visual comparison of the Ford Fuel Injectors, picture by TMoss:
http://www.veryuseful.com/mustang/tech/engine/images/Ford_Injector_Guide.jpg

Convertible top motor wiring http://www.veryuseful.com/mustang/tech/engine/images/mustang88VertTopMotorCkt.gif

Engine mounted fuel injector harness
http://www.veryuseful.com/mustang/tech/engine/images/mustangEngineHarness.gif

Location of the TPS, IAB, and the 10-pin connectors on a 5.0, picture by TMoss:
http://www.veryuseful.com/mustang/tech/engine/images/TPS_IAB_Pic.jpg

Starter circuit
http://forums.stangnet.com/attachment.php?attachmentid=21328&d=1080916057

Alternator diagram for 94-95 Mustangs.
http://www.veryuseful.com/mustang/tech/engine/images/Mustang-94-95-Alt.gif