Engine Timing Help/Question
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Junior User
Joined: Jul 2010
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From: Brusly, LA
Engine Timing Help/Question
1986 F-150 302 V-8 Fuel Injected
If have the TFI-IV Ignition System with the ICM mounted on distributor
I’ve been having trouble with my truck dying on me once it gets hot (not overheating). Once it cools down its starts right up again.
I changed some parts but the problem is still there. First I changed the Ignition Control Module (ICM), second the coolant temperature sensor, third the external fuel pump (it’s been making noise), and finally the ignition coil/stator.
Anyway, on to the timing question. With SPOUT disconnected the timing mark is steady as a rock, but with the spout connected it jumps around a bit. And as the engine gets hotter the more the timing mark jumps. At this point the engine is running rough and if I continue to let it run it will eventually stumble and die. Why is this happening?
I should mention that I did move the ICM off the distributor to a cooler area. I’m beginning to wonder if moving it back would solve the problem, but I’m curious to know what you think before I do that.
The next thing I’ll likely do is change the fuel filter and add some fuel injector cleaner to the tank. I’m at a loss at this point.
If have the TFI-IV Ignition System with the ICM mounted on distributor
I’ve been having trouble with my truck dying on me once it gets hot (not overheating). Once it cools down its starts right up again.
I changed some parts but the problem is still there. First I changed the Ignition Control Module (ICM), second the coolant temperature sensor, third the external fuel pump (it’s been making noise), and finally the ignition coil/stator.
Anyway, on to the timing question. With SPOUT disconnected the timing mark is steady as a rock, but with the spout connected it jumps around a bit. And as the engine gets hotter the more the timing mark jumps. At this point the engine is running rough and if I continue to let it run it will eventually stumble and die. Why is this happening?
I should mention that I did move the ICM off the distributor to a cooler area. I’m beginning to wonder if moving it back would solve the problem, but I’m curious to know what you think before I do that.
The next thing I’ll likely do is change the fuel filter and add some fuel injector cleaner to the tank. I’m at a loss at this point.
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From: Virginia
You have to be careful with the wiring to the ICM. The factory used a shielded wire, as the control signals from the computer are very prone to noise and interference. In fact this factory shielded wire causes problems sometimes, as the shield on the end of the wire can get damaged and short the signal wire out intermittently.
Thread Starter
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Junior User
Joined: Jul 2010
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From: Brusly, LA
You have to be careful with the wiring to the ICM. The factory used a shielded wire, as the control signals from the computer are very prone to noise and interference. In fact this factory shielded wire causes problems sometimes, as the shield on the end of the wire can get damaged and short the signal wire out intermittently.
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Joined: Jan 2001
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From: Virginia
I am not sure you could wrap the wires and help it, though I guess you could try tin foil or something. Just be sure the tin foil is grounded, and it has to be grounded to the original shield, which was grounded only on one end(the computer end). If you have a shielded wire, the shield has to be grounded to give a path for the noise to follow, and you should not ground the shield at both ends, only one end.
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Junior User
Joined: Jul 2010
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From: Brusly, LA
I bought a Motorcraft TFI module and also a Motorcraft ignition coil/stator.
The only shielding that I can see to do is for the number 1,2, and 6 wires. See Fuel Injection Harness Ingition Circuit, about half way down page.
Note:
I decided to remount the ICM back on the distributor to help eliminate my moving it as the source of my problem. Anyway, I started a new thread that does a better job showing how I got to this point.
Here's the new thread: Engine Stalls and Dies after Heat Soak
The only shielding that I can see to do is for the number 1,2, and 6 wires. See Fuel Injection Harness Ingition Circuit, about half way down page.
Note:
I decided to remount the ICM back on the distributor to help eliminate my moving it as the source of my problem. Anyway, I started a new thread that does a better job showing how I got to this point.
Here's the new thread: Engine Stalls and Dies after Heat Soak
