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issue with misfire on 96 s10 with 4.3

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Old 05-12-2013, 05:57 PM   #1
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issue with misfire on 96 s10 with 4.3

so here is my issue iI have a 1996 s10 with a 4.3 Vortec and its missing around 1000 to 2000 rpm iI have replaced the map sensor 2 o2 sensors on passenger side one after the cat and one before the cat iI replaced the cap and rotor along with the sensor inside the cap plus the plugs and wires now when iI have the motor running i can put pressure on the cap counterclockwise and get the motor up to where it would miss and it would clear up and when i put pressure on it clockwise it would get worse would that be the distributor gear ththat's shot or would it be something else
Old 05-12-2013, 06:01 PM   #2
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Re: issue with misfire on 96 s10 with 4.3

And when I have the cap and rotor off should I be able to move that mounting plate for the rotor up and down and rotate it back and forth
Old 05-12-2013, 11:36 PM   #3
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Re: issue with misfire on 96 s10 with 4.3

You should not be able to rotate the distributor, unless the hold down clamp bolt is loose. You are changing the cam retard when you do that. You need to get the cam retard checked and the distributor tightened down.

Yes for the second question.

Use a quality cap, rotors, and plugs in these motors (preferably AC Delco)
Use dielectric grease on the contacts inside that cap to prevent corrosion.
And on the wires to keep moisture out.
Old 05-12-2013, 11:50 PM   #4
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Re: issue with misfire on 96 s10 with 4.3

the housing for ddistributor is tight I'm talking about where you screw the rotor into
Old 05-13-2013, 12:08 AM   #5
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Re: issue with misfire on 96 s10 with 4.3

It could be a worn gear.

It could also be associated with a rotor phasing problem; http://www.s10forum.com/forum/f107/d...=rotor+phasing
If rotor phasing is the problem, rotating the distributor body clockwise would make it worse as you are making the rotor/cap gap larger. Even through the distributor is tight, twisting on the cap may allow just enough movement to worsen the rotor gap to the point of making it worse.

If you elongated the body clamp bolt hole so that the distributor could be rotated a bit counter clockwise it may fix your problem. I would pull the distributor and check the gear, replace if needed, and elongate the hole. Then advance the distributor by rotating it counter clockwise and take advantage of the elongated hole.
Old 05-13-2013, 12:09 AM   #6
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Re: issue with misfire on 96 s10 with 4.3

let me reword it cause i I might have said it weird when the whole unit is put together iI run the truck and get the rpm up to around 1000 to 2000 rpm . I put my hand on the cap and turn it counter clockwise it doesnt actually turn . When iI do that it seams to clear the misfire when iI do the same but clockwise it gets worse now the question is would that be the distributor itself be bad or is it something else and when iI have the cap off the plate where the rotor gets mounted to is it supposed to rotate about a quarter of an inch freely along with going up and down and there is ac delco cap and rotor along with all of the other stuff along with dilectric grease
Old 05-13-2013, 01:05 AM   #7
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Re: issue with misfire on 96 s10 with 4.3

Quote: Originally Posted by ecpeterson8705
is it supposed to rotate about a quarter of an inch freely along with going up and down
NO!

That shaft should next to NO free play, left & right. I believe that you will find that the gear is wore. I pulled a distributor with about a 1/8" play and the gear was really bad.

I understand what you posted, the distributor is not loose, but you are flexing the plastic cap and maybe it's not down tight but if the gear is worn it will cause cam/crank correlation problem causing a misfire. Flexing the distributor parts can change things. It's great that you tried twisting the distributor parts.
Old 05-13-2013, 01:22 AM   #8
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Re: issue with misfire on 96 s10 with 4.3

I'm going to pull the distributor tomorrow. and i got thicker screws so iI could tighten it down the old holes were striped out for the cap. I figured the misfire seamed to chase the firing order when it would misfire and so iI remember on my old suburban that sometimes iI had to turn the distributor a bit to get it back to normal and would only happen after hard off roading . Great in site no one could give me a real answer as to what is going on I'll post tomorrow on what iI find
Old 05-13-2013, 01:32 AM   #9
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Re: issue with misfire on 96 s10 with 4.3

Now if the distributor gear is shot would I have to change the cam shaft as well ior would that be fine
Old 05-13-2013, 01:38 AM   #10
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Re: issue with misfire on 96 s10 with 4.3

Cam shaft gear is much harder, no worries there.

When you go to replace the gear, take a very close look at where the gear teeth are in relation to the roll pin. On one side of the gear the roll in is between the teeth, on the other side the roll in is in line with one tooth. Don't get the gear on the wrong way of you will be back to where you are now! Make the shaft and the replacement gear before you take it apart.

This might help, I didn't have this info when I last replaced gears, so I can't say it's all correct, just make sure you match things up before you take it apart.
Old 05-13-2013, 01:44 AM   #11
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Re: issue with misfire on 96 s10 with 4.3

sweet cause iI wasnt looking forward to changing that out . Will iI have to worry about shavings from the gear if it is broken. Just want to be prepared for whatever might happen
Old 05-13-2013, 01:51 AM   #12
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Re: issue with misfire on 96 s10 with 4.3

Now is that picture for just replacing the gear or for the whole distributor . Cause I'll probably just replace the whole distributor
Old 05-16-2013, 12:11 AM   #13
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Re: issue with misfire on 96 s10 with 4.3

The pic shows the relationship of the gear to the rotor. A new distributor should already be correct.
Old 05-16-2013, 03:24 PM   #14
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Re: issue with misfire on 96 s10 with 4.3

So I pulled the distributor and the gear was toast. Along with that the shaft was bent as well so good thingI had the parts store order me a new one I'll let you know how it turns out
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