Ignition issues
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1st Gear
Joined: Jan 2023
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Ignition issues
Hello! I am new to this group and a drive a 1984 f150 single cab with a 351w and 3 speed auto. It is also a 4wd. My issue, is when I'm driving around after 10 min with minimal to no load on the engine. It will randomly cut ignition for 2 to 3 seconds. I have replaced the coil. Could this be the ignition module starting to fail? I have new plugs, wires and cap already. It also just started doing this. Please help 😀😀
Moderator
Joined: Jan 2001
Posts: 56,984
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From: Virginia
Ignition module would be a good guess. If it turns out not to be the problem, you can throw it under the seat, it's always good to have a spare. While you are changing the module, look inside the connectors for corrosion and loose wires also.
Logistics Pro
Joined: Jun 2017
Posts: 3,964
Likes: 512
From: Edmond, OK
You can have the ignition module& the coil tested at the auto parts store. It's not unheard of for a new part to be bad either. What brand ignition coil did you get? It's probably a good idea to stick with Motorcraft.
FTE Legend
Joined: Nov 2015
Posts: 30,917
Likes: 4,123
From: Angier, NC
When modules start showing signs is after they heat up, no spark.
Let them cool down and you get spark till it heats up again.
The TFI units seam to be really bad at this as they sit inside the hot distributor.
Dave ----
Lead Driver
Joined: Nov 2013
Posts: 7,174
Likes: 1,174
Can you please post a picture of your distributor? Trying to determine which ignition system you have.
Does it have a silver canister on the side, kinda looks like a flying saucer? It will have a vacuum line attached. This is the Duraspark system, which will also have a rectangular control module on the driver's side inner fender. This remote module is about the size of a paperback. If you have this system, remove the distributor cap and rotor, and look at the two flexible wires going to the pickup coil. The pickup coil sits on a plate that rotates with the vacuum advance, and the wires end up rubbing against the distributor housing at low throttle settings when vacuum is high. If the wiring looks good, the next likely culprit is the control module over on the inner fender.
Or does your distributor have no vacuum line, and small rectangular box sticking out on the side? That's the TFI system, and that control module (on the side of the distributor) is notorious for failing. If you have that system, I'd be willing to gamble your time and money on a new control module.
Does it have a silver canister on the side, kinda looks like a flying saucer? It will have a vacuum line attached. This is the Duraspark system, which will also have a rectangular control module on the driver's side inner fender. This remote module is about the size of a paperback. If you have this system, remove the distributor cap and rotor, and look at the two flexible wires going to the pickup coil. The pickup coil sits on a plate that rotates with the vacuum advance, and the wires end up rubbing against the distributor housing at low throttle settings when vacuum is high. If the wiring looks good, the next likely culprit is the control module over on the inner fender.
Or does your distributor have no vacuum line, and small rectangular box sticking out on the side? That's the TFI system, and that control module (on the side of the distributor) is notorious for failing. If you have that system, I'd be willing to gamble your time and money on a new control module.
Cross-Country
Joined: Sep 2022
Posts: 58
Likes: 14
The thing with store testing is it's not under load and the big one no heat.
When modules start showing signs is after they heat up, no spark.
Let them cool down and you get spark till it heats up again.
The TFI units seam to be really bad at this as they sit inside the hot distributor.
Dave ----
When modules start showing signs is after they heat up, no spark.
Let them cool down and you get spark till it heats up again.
The TFI units seam to be really bad at this as they sit inside the hot distributor.
Dave ----
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