460 in E350 Misfire problems
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Joined: Jul 2003
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460 in E350 Misfire problems
Greetings,
I've got a 460 in a 94 E350 van (74K mi) and can't seem to solve a misfire problem. It seems there is so much great advice on this forum I thought I'd give it a shot here.
A month or so ago I developed a slight misfire. It would miss only occasionally when driving easy...not accelerating or decelerating, just level easy cruising. If I back off the gas very slightly, it would miss a bit.
The problem has gotten worse in the last month and now includes a slight intermittant miss at idle also. Most driving is fine, but just at a certain load it will misfire. It does it with the AT in or out of OD.
With a timing light it appears we can see the light go goofy during the idle miss, which seems to confirm an ignition problem.
To date:
New Plugs, wires, distributor ignition module, ignition computer, MAP sensor. No help.
Any ideas? Is there a central computer that runs all of this? What's the chance that is bad? Coil?
Thanks,
Russ
aka Dr. Destructo
I've got a 460 in a 94 E350 van (74K mi) and can't seem to solve a misfire problem. It seems there is so much great advice on this forum I thought I'd give it a shot here.
A month or so ago I developed a slight misfire. It would miss only occasionally when driving easy...not accelerating or decelerating, just level easy cruising. If I back off the gas very slightly, it would miss a bit.
The problem has gotten worse in the last month and now includes a slight intermittant miss at idle also. Most driving is fine, but just at a certain load it will misfire. It does it with the AT in or out of OD.
With a timing light it appears we can see the light go goofy during the idle miss, which seems to confirm an ignition problem.
To date:
New Plugs, wires, distributor ignition module, ignition computer, MAP sensor. No help.
Any ideas? Is there a central computer that runs all of this? What's the chance that is bad? Coil?
Thanks,
Russ
aka Dr. Destructo
Posting Guru
Joined: Mar 2003
Posts: 1,349
Likes: 3
From: Cloud USA
460 in E350 Misfire problems
Check your timing chain for slack. The easiest way to do it is turn the crank 30 degrees clock wise and then watch the rotor in the distributor for movement when you turn the crank counter clockwise. I believe 5 degrees is the service limit. I just changed mine today actually and it runs great now. I had about 12 degrees of backlash. 204,000 miles. A warn timing set is common in the 460's they wont be able to keep there time and it screws with the computer. Also check the fuel pressure. it should be about 40psi. IT could be a failing pump or pressure regulator.
Posting Guru
Joined: Jan 2003
Posts: 1,061
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From: Still under the hood in O
460 in E350 Misfire problems
If that checks out okay, another easy test is pull the distributor and check the shaft for excess play (side to side).
Then you can check out the coil. I don't have the specs to test for on your 460. It's real helpful when the book says "Swap with a known good one, if spark is present with good one replace coil".
Then you can check out the coil. I don't have the specs to test for on your 460. It's real helpful when the book says "Swap with a known good one, if spark is present with good one replace coil".
Lead Driver
Joined: Feb 2003
Posts: 8,140
Likes: 4
From: Oak Harbor, OH
460 in E350 Misfire problems
I would spray the lower intake where it meets the head with some carb cleaner while it's running, if the rpms change you found a vaccum leak. You can also spray around where the throttle body is mounted to the intake.
Laughing Gas
Joined: Jun 2003
Posts: 1,166
Likes: 0
From: Chino, California
460 in E350 Misfire problems
Use a propane bottle, it's safer than having a flammable liquid puddling on the hot engine parts. Propane is what the pro's use.
Turn on the propane using a torch tip. YoU can add rubber hose to the tip to get it into tight places. Of course, you do not ignite it!!
My uncle worked at he Ford assembly plant in Pico Rivera, California in the emissions trouble-shooting department and they always used propane.
Turn on the propane using a torch tip. YoU can add rubber hose to the tip to get it into tight places. Of course, you do not ignite it!!
My uncle worked at he Ford assembly plant in Pico Rivera, California in the emissions trouble-shooting department and they always used propane.
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Elder User
Joined: Jul 2003
Posts: 870
Likes: 1
From: Upstate NY Rochester
460 in E350 Misfire problems
Just some tid-bit info. If you plan on using soldering type propane, make sure it is in the up-right position for at least 20 minutes before using. Remember, it is liquid.... Short spurt's of fuel will be released when first used if it has been on it's side for awhile. Also, the same being true while in use. Tipping the bottle has the same effect. Flame or no flame, it does present a safety issue. Keep a fire extinguisher and a blanket near-by. Extinguisher for the truck....Blanket to wrap yourself up in, in case of the worst... Good luck and BE careful..... We'll talk with you guys later.
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