I6 misfiring Help???
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Freshman User
Joined: Apr 2002
Posts: 40
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I6 misfiring Help???
I have a 85 Ford F150 4.9L 4 spd (factory no pollution ) with a duraspark II ignition.It started to misfire on acceleration and backfire out of the exhaust a few days ago. Plugs, wires ,cap and rotor, are good . Fuel seems to be getting to the carb.
I started it up this morning
and it ran fine for about 10mins I drove it around the block and its started misfiring as i was accellerating out of 2nd gear.I runs as if it has bad wires or cap that are wet.
I had the ignition module checked at the parts store
and its fine. I put on a new coil and there is no difference.
Vacuum advance seems to be working fine to. Help
I started it up this morning
and it ran fine for about 10mins I drove it around the block and its started misfiring as i was accellerating out of 2nd gear.I runs as if it has bad wires or cap that are wet.
I had the ignition module checked at the parts store
and its fine. I put on a new coil and there is no difference.
Vacuum advance seems to be working fine to. Help
Senior User
Joined: Jan 2002
Posts: 492
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From: Spokane WA, USA
I6 misfiring Help???
I'm having the same problem. New wires and plugs- Starts to miss on acceleration just out of 2nd gear. Funnu thing is that it started right after the new plugs and wires. Anybody have any ideas?
Posting Guru
Joined: Jun 1999
Posts: 1,083
Likes: 1
I6 misfiring Help???
Pull and check each plug for spark. Check the plug/wire boots and the cap/wire boots, and check the boot of the coil/dist. wire in both places. Also check your dist. cap for moisture (inside). And, most importantly, check your wire routing/firing order. That's where I would start. Maybe others can give some advice, too?
New User
Joined: Apr 2002
Posts: 1
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From: chester usa
I6 misfiring Help???
what is your vacumm reading at idle, recheck your timing the 4.9 has problems with the dist bolt backing out and the the dist will rotate off and usually becomes harder to start. also check the inside of the distributor the pickup assemblies trigger can work its way loose over time many of them are held in by the plastic tabs that are heated and melted down over the holes and then the pickup will not fire correctly. larry
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Freshman User
Joined: Apr 2002
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I6 misfiring Help???
Thanks for all your responses.
Truck is running great.
As I first suspected, it was the ignition module.
When brought it to the local parts store to get it tested
it checked out fine???So this led me around checking my entire
electical system right back to the ignition module. So I
went to wreckers bought a module for $15 slapped it on
and presto the truck accelerates without misfiring or backfiring.
Truck is running great.
As I first suspected, it was the ignition module.
When brought it to the local parts store to get it tested
it checked out fine???So this led me around checking my entire
electical system right back to the ignition module. So I
went to wreckers bought a module for $15 slapped it on
and presto the truck accelerates without misfiring or backfiring.
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