Misfire on cold start
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Joined: Jul 2024
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Misfire on cold start
Please see attached video.
1995 F!50 4.9 with 5 speed manual.
As you can see in the video the tachometer is erratic. This only happens on cold starts only. The engine is misfiring pretty bad while this is happening. Once the engine is warm the problem goes away. The only part that has been changed so far is the ignition control module which made no difference. You can make the misfire stop briefly by flooring it only for it to return within a couple of seconds so I'm thinking maybe an over fuel situation but that does not, at least in my mind, explain the erratic tachometer. In the video you can see the speed relative to the tachometer reading that the tach is reporting something other than what the engine is actually turning. No check engine light is on. Any help would be greatly appreciated. 20240730_113351_1084710077371786.avi
1995 F!50 4.9 with 5 speed manual.
As you can see in the video the tachometer is erratic. This only happens on cold starts only. The engine is misfiring pretty bad while this is happening. Once the engine is warm the problem goes away. The only part that has been changed so far is the ignition control module which made no difference. You can make the misfire stop briefly by flooring it only for it to return within a couple of seconds so I'm thinking maybe an over fuel situation but that does not, at least in my mind, explain the erratic tachometer. In the video you can see the speed relative to the tachometer reading that the tach is reporting something other than what the engine is actually turning. No check engine light is on. Any help would be greatly appreciated. 20240730_113351_1084710077371786.avi
Last edited by milesp00; Jul 30, 2024 at 05:12 PM.
Senior Member
Joined: Oct 2016
Posts: 3,705
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From: Parts Unknown
Does this happen at idle and higher RPM's while in park? I have had misfires before but the tach never did anything like that while I was cruising. You sure it's not a transmission issue?
Last edited by raski; Jul 30, 2024 at 03:49 PM.
Senior Member
Joined: Aug 2021
Posts: 995
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From: Maryland
I would check the connections at the ignition coil for corrosion and check the ECM relay socket for corrosion.
How are your battery terminals? They're worth checking, as well as the connections at the fender mounted starter relay (aka solenoid), and the cable from the battery negative terminal, to the engine block and frame, and it's terminal ends.
How are your battery terminals? They're worth checking, as well as the connections at the fender mounted starter relay (aka solenoid), and the cable from the battery negative terminal, to the engine block and frame, and it's terminal ends.
