1986 300 6cylinder engine shaking problems
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1986 300 6cylinder engine shaking problems
Hello guys, nice to join the forums
Just bought a 1986 F150 with 300 6cylinder and 3spd auto tranny.
Truck is equipped with a stock carb and all stock parts
List of new parts-
Brand new carberator
Brand new ignition module
new wires/plugs
new cap and rotor
No apparent vacuum leaks, no apparent head gasket issues, etc
PROBLEM: At all times engine has a miss/shake which is noticeable throughout the driving/rpm range.
Shakes badly until about 45mph and then kind of goes away but is still there.
Does shaking in park, drive, reverse, etc
Exhaust seems good, no smoke, no antifreeze smell, etc
What could be causing this?
Noticed a O2 sensor attached to exhaust manifold, but O2 sensor wouldn't cause such an issue at startup would it?
Truck starts and runs fine except for bad miss/shake
Thought it could be the TFI ignition module, got a new one, no effect
Any ideas?
Thanks guys!
Just bought a 1986 F150 with 300 6cylinder and 3spd auto tranny.
Truck is equipped with a stock carb and all stock parts
List of new parts-
Brand new carberator
Brand new ignition module
new wires/plugs
new cap and rotor
No apparent vacuum leaks, no apparent head gasket issues, etc
PROBLEM: At all times engine has a miss/shake which is noticeable throughout the driving/rpm range.
Shakes badly until about 45mph and then kind of goes away but is still there.
Does shaking in park, drive, reverse, etc
Exhaust seems good, no smoke, no antifreeze smell, etc
What could be causing this?
Noticed a O2 sensor attached to exhaust manifold, but O2 sensor wouldn't cause such an issue at startup would it?
Truck starts and runs fine except for bad miss/shake
Thought it could be the TFI ignition module, got a new one, no effect
Any ideas?
Thanks guys!
Posting Guru
Joined: Aug 2009
Posts: 2,271
Likes: 2
From: Mexia, TX
Look over the wiring for the coil, ignition module, distributor and their related parts and see if any wires are coming apart or loose. I had a wire coming apart at the coil once and it caused a bad miss, mainly at low RPM.
I don't think the O2 sensor would cause that, since if I recall, the computer only reads the O2 sensor when the engine has reached operating temperature.
I don't think the O2 sensor would cause that, since if I recall, the computer only reads the O2 sensor when the engine has reached operating temperature.
Moderator
Joined: Jan 2001
Posts: 56,984
Likes: 2,738
From: Virginia
What I would do is loosen all the sparkplug wires either on the sparkplugs or on the dist cap, whichever is easier to get to. Start the engine, and put some gloves on, and take some long nosed pliers and grab one sparkplug wire and pull it off the plug. Does the shaking get worse? If yes, then that cylinder is good. Is there no change with the wire off? If so, then that cylinder is no good. Do all six. Then you can go from there.
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Junior User
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Thanks guys it was the #6 sparkplug, which was fairly new looking and a platinum...
Runs good now for the most part, new carb, new coil, wires and plugs, new ignition module, BUT still has a O2 sensor I haven't messed with and have no idea whether it's OK or not...
It does run a little rough when first starting hot or cold...but it goes away after a few minutes...not sure what that could be.
Also, AC/heater control will not shift between vent, etc it just stays on vent always...how would I fix that I assume it's vac operated?
Seems like this truck is a precursor to a EFI 87 as it has an O2 sensor and other items usually found on a EFI engine...?
Runs very quiet though I wish I could swap in a AOD or E4OD...is that possible?
Thanks
Runs good now for the most part, new carb, new coil, wires and plugs, new ignition module, BUT still has a O2 sensor I haven't messed with and have no idea whether it's OK or not...
It does run a little rough when first starting hot or cold...but it goes away after a few minutes...not sure what that could be.
Also, AC/heater control will not shift between vent, etc it just stays on vent always...how would I fix that I assume it's vac operated?
Seems like this truck is a precursor to a EFI 87 as it has an O2 sensor and other items usually found on a EFI engine...?
Runs very quiet though I wish I could swap in a AOD or E4OD...is that possible?
Thanks
Elder User
Joined: May 2012
Posts: 978
Likes: 1
From: Covington VA
Is it a aftermarket carb?
Wouldnt that stick the dizzy to one timing with no advancement. Or is that only by removing smog stuff.
Wouldnt that stick the dizzy to one timing with no advancement. Or is that only by removing smog stuff.
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Junior User
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It's a remand autolite or carter or something looks like a shiny aluminum one barrel and it seems to have some solenoids and a TPS throttle position sensor
Just checked the O2 sensor looks brownish black but no real "coatings" on it I guess it's OK??
Is there a test for the O2 sensor? A new one's only $15 so maybe just get a new one?
OH
Big problems I have is all the gadgets in the air cleaner don't work, the vac motor and temp switches no longer seem to work and cant find them at auto store
Maybe rockauto has them but I don't know what exactly they're called, found the vac motor but the vac temp switch cant find
thanks
Just checked the O2 sensor looks brownish black but no real "coatings" on it I guess it's OK??
Is there a test for the O2 sensor? A new one's only $15 so maybe just get a new one?
OH
Big problems I have is all the gadgets in the air cleaner don't work, the vac motor and temp switches no longer seem to work and cant find them at auto store
Maybe rockauto has them but I don't know what exactly they're called, found the vac motor but the vac temp switch cant find
thanks
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Moderator
Joined: Jan 2001
Posts: 56,984
Likes: 2,738
From: Virginia
I believe a regular code reader will work on your truck. If you have a bad O2 sensor, it would give you a code related to that.
On your temp sensor in the aircleaner, the first thing I would do is get the engine running, and pul the vacuum line off the aircleaner that comes from the engine, and hook it directly to the flapper motor in the aircleaner. The motor should shut. That would test it and if it works, you shouldn't have to buy one.
If that works take a look at the sensor. 1st thing to try is make sure the lines are on it correctly. It matters which one the flapper motor hooks to.
If you still can't get it to work, I have had 100% success taking the plastic piece off the top of the temp sensor, and fiddling with the adjustment(there is a little screw that adjusts this thing) Each time I mess with it and move the valve up and down with my finger, it starts working.
On your temp sensor in the aircleaner, the first thing I would do is get the engine running, and pul the vacuum line off the aircleaner that comes from the engine, and hook it directly to the flapper motor in the aircleaner. The motor should shut. That would test it and if it works, you shouldn't have to buy one.
If that works take a look at the sensor. 1st thing to try is make sure the lines are on it correctly. It matters which one the flapper motor hooks to.
If you still can't get it to work, I have had 100% success taking the plastic piece off the top of the temp sensor, and fiddling with the adjustment(there is a little screw that adjusts this thing) Each time I mess with it and move the valve up and down with my finger, it starts working.
Lead Driver
Joined: Jul 2009
Posts: 6,477
Likes: 19
From: Sheffield, AL
Thanks guys it was the #6 sparkplug, which was fairly new looking and a platinum...
Runs good now for the most part, new carb, new coil, wires and plugs, new ignition module, BUT still has a O2 sensor I haven't messed with and have no idea whether it's OK or not...
It does run a little rough when first starting hot or cold...but it goes away after a few minutes...not sure what that could be.
Also, AC/heater control will not shift between vent, etc it just stays on vent always...how would I fix that I assume it's vac operated?
Seems like this truck is a precursor to a EFI 87 as it has an O2 sensor and other items usually found on a EFI engine...?
Runs very quiet though I wish I could swap in a AOD or E4OD...is that possible?
Thanks
Runs good now for the most part, new carb, new coil, wires and plugs, new ignition module, BUT still has a O2 sensor I haven't messed with and have no idea whether it's OK or not...
It does run a little rough when first starting hot or cold...but it goes away after a few minutes...not sure what that could be.
Also, AC/heater control will not shift between vent, etc it just stays on vent always...how would I fix that I assume it's vac operated?
Seems like this truck is a precursor to a EFI 87 as it has an O2 sensor and other items usually found on a EFI engine...?
Runs very quiet though I wish I could swap in a AOD or E4OD...is that possible?
Thanks
Perhaps this will help regarding the AC/heater control... use the "SEARCH" feature as there are many postings about this subject.
https://www.ford-trucks.com/forums/9...t-working.html
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