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What does the distributor air gap do?

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Old 01-26-2011, 08:01 PM
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What does the distributor air gap do?

I was testing stuff just for the hell of it and came across the "air gap." I got out my feeler gauges and the biggest size I could fit in there was a .53 mm. On this page: http://personal.utulsa.edu/~nathan-b...12onvehicl.pdf , it says .2 - .4 mm AND .2 - .5 mm.

Which one is it?

Can anyone explain what this "gap" does so I can wrap my brain around it?
Old 01-26-2011, 08:57 PM
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If there is 'no' air gap the Signal Rotor will impact the Pickup Coil and damage both the Signal Rotor and Pickup Coil. If the air gap is 'greater' than the .5mm limit the magnetic field from the signal rotor will be insufficient to be properly detected by the Pickup Coil or may not be detected at all. The results will be no spark from the ignitors or erratic spark from the ignitors.
As for the .1mm (.004") discrepancy between the two ranges given, don't worry about it. To put it in perspective, the average human hair is .1mm in diameter. To put it another way- you're splitting hairs (pun intended).
Old 01-26-2011, 08:57 PM
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http://www.picoauto.com/tutorials/trigger-signals.html
This page should help explain it a little better. It looks like you have a Hall Effect style of distributor whereas the 22re's have the Permanent Magnetic Pickup style.

The air gap is simply the operational range that will produce the acceptable change in the magnetic field as the rotor (not the one in the top of the cap) spins by. Obviously too close = carnage and too loose = bad/no signal.
Old 01-26-2011, 09:01 PM
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Originally Posted by Sansocal
I was testing stuff just for the hell of it and came across the "air gap." I got out my feeler gauges and the biggest size I could fit in there was a .53 mm. On this page: http://personal.utulsa.edu/~nathan-b...12onvehicl.pdf , it says .2 - .4 mm AND .2 - .5 mm.

Which one is it?

Can anyone explain what this "gap" does so I can wrap my brain around it?
The air gap there talking about is the gap between the pick up coil and the stator (i think that`s what its called,the star looking thing in the distributor) in the distributor. The last pick up coil i installed i set at 10 thousandths of an inch, they give you a range in the fsm.
Old 01-27-2011, 05:55 AM
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So the signal the magnets make when they are spinning go to the ignitor, then coil? This is interesting considering I also have a code 14, but no CEL.
Old 01-27-2011, 06:06 AM
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correct mag pickup/hall sensor to igniter to coil back to dizzy.
Old 12-22-2013, 05:42 PM
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My gap is .021 mm, does that .005mm setting apply to a 87 22re 4runner turbo? If so then I just figured out why my injectors won't spray
Old 12-23-2013, 01:27 PM
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Originally Posted by randu2020
My gap is .021 mm, does that .005mm setting apply to a 87 22re 4runner turbo? If so then I just figured out why my injectors won't spray
What?

.021mm is less than 0.001 inches (as in; thinner than aluminum foil). Are you sure you're not using an SAE feeler set, and measured .021 inches? (which would be 0.53mm, about) And what .005mm "setting" are you talking about? Are you referring to .2-.5mm ?

Yes, units count.
Old 12-24-2013, 02:08 AM
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randu2020..If you are getting fire to your plugs, there are other reasons that the injectors wont spray. I have not messed with turbo, but seems to me that it is quite similar to non turbo. I am interested in this thread as I have no fire to plugs as well. I think I have a bad wire some where that I have to start tracing out. Waiting on warmer weather.

Check your Pick up Coil inside the distributor for no fire on the plugs. Here is some info about the Pickup Coil>>> https://www.yotatech.com/forums/f198...l#post52121343 The Pickup Coil is a solid piece of equipment, but does fail.

You do need to get your Air Gap set correctly.

Last edited by Terrys87; 12-24-2013 at 03:42 AM.
Old 05-15-2015, 04:11 PM
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Can it cause misfire in two of the cylinders and not all four
Old 05-15-2015, 04:18 PM
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When I pull off #1 or #4 cylinder wire the truck dies right away
When I pull off 2 or 3 there's hardly a change.
The plugs were fowled I replaced them but not much difference
Old 05-15-2015, 07:49 PM
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worn out distributor

Bad bearing or specifically the race on the distributor shaft forming an ellipse where two opposing contacts are in range and the two others swing wide, how many miles?? Can't remember which year but prior can be repaired, after requires replacement.. Just a possibility, saw it once, you could almost see the wobble when you pressed on the star and definitely could feel it..
Old 05-16-2015, 04:34 AM
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87 1 ton cab and chasis

Originally Posted by shadowbirdie
Bad bearing or specifically the race on the distributor shaft forming an ellipse where two opposing contacts are in range and the two others swing wide, how many miles?? Can't remember which year but prior can be repaired, after requires replacement.. Just a possibility, saw it once, you could almost see the wobble when you pressed on the star and definitely could feel it..
Thanks, I kind of hoped it was something like that. I ordered a pick up before you responded. There is no play in the bearing of the distributor shaft but you think I should get the entire distributed instead ? 50.00 difference!
Probably 250,000 miles on the truck, motor has 75,000 + or -...
Old 05-17-2015, 08:45 AM
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I'd say do more research if not the DD

Money adds up fast in these old units, I keep expense to the minimum, but do the best I can (no goobering), and no paid mechanics. I can't see the pickup fixing a bearing problem, this part either works or it doesn't unless somehow it is contaminated with ferrous dirt (bearing or race material), or impact damage. If I found this issue, as I'm not loaded, I'd hit the boneyard and find the prettiest, cleanest one I could find and replace the whole thing as a unit, but that's me, and that's after absolutely confirmed by checking runout by dial indicator (something not generally available to rent at an auto parts store)
Old 05-17-2015, 11:16 AM
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Originally Posted by Catcher5
When I pull off #1 or #4 cylinder wire the truck dies right away
When I pull off 2 or 3 there's hardly a change.
The plugs were fowled I replaced them but not much difference
those symptoms could be caused by a variety of things.
Old 05-17-2015, 02:27 PM
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^^^ Agree with this, I would make sure I had a good tune up before starting to trouble shoot. If your plugs were fouled or worn, how is the rest of the parts. Fouled could be an oil burner but you dont really say all the symptoms.

I have seen these trucks with orginal plug wires. Once you got great quality parts in it then I would see what problems persist. Pulling one plug wire should not kill the truck, it should keep running.

I get my cap, rotor, oil filter, and plugs from the dealer. About the same price you would pay at the part store and better quality. My plug wires I get are Denso for $27 including shipping if I recall right from ebay. I checked the dealer for Denso wires and it was $83. You can get great quality parts for cheaper prices, just have to check around.
Old 05-17-2015, 03:50 PM
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I'll try the wires and cap they are only 6 months old though thanks
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