Conflicting answers on the firing order of my 86 S10.


Asked by Apr 29, 2015 at 12:36 PM about the 1986 Chevrolet S-10 Durango Standard Cab 4WD SB

Question type: Maintenance & Repair

I have and 86 S10 pickup 2.8 V6. It is running very rough and wont accelerate hardly at all. I have been told it is a timing issue. I set the timing with a timing light to 8 btdc. It runs horrible there. I have had multiple answers on the firing order. 123456 on the distributor 135 on the passenger side and 246 on the drivers side. But have also been told that the number one plug is the driverside front? So could someone please help!

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multiple sources

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Thanks for the help. But here again is my problem. I see your photo but on this forum I also saw a photo of just the opposite so that is why I am confused. I currently have the firing order set this way and it is running terrible. The only difference in mine is when I set my truck on tdc the rotor under the cap is pointing to the 4 in this picture. But that is where my number 1 wire is so I was told that was ok. Can you please tell me if that is ok? Thanks

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#1 cylinder is on the drivers side on the 4.3L and different firing this to see all of it but it's NOT your engine

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Fordnut the last pic you posted says note the distributor latch position. That being noted my latches are the exact opposite? The driverside latch is towards the front and the passenger latch is towards the back what does that mean?

Huh. I saw that also, and can't explain it. Let me look again

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Ok. Thanks. I am not a mechanic by trade just a lowly journeyman electrician so engines are not my best!

This is from Haynes manual. Yes, there is conflicting information but it looks like the mix-up is between the 2.8 and 4.3 ..both V6

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See where #1 should be? If your rotor is pointing at #4 its 180° off.

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I like that one! So my next question your opinion do I need to turn my distributor and or the cap to make it match that picture. Because currently it is opposite of that? And would that affect the way the motor runs if it is maybe 180 out?

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Quote "Fordnut the last pic you posted says note the distributor latch position. That being noted my latches are the exact opposite? The driverside latch is towards the front and the passenger latch is towards the back what does that mean? ....Looks like its is 180 off


In response to you last post. Its 180 off even if that is where I have the #1 wire? When on tdc the rotor is not pointing at the #1 hole but pointing the opposite of that. But again that is where the #1 wire is.

We were typing at the same time.... so yes, that's what I would do


Sorry I don't want to be a pest I am just wanting to verify cause a mechanic I am not. I appreciate all your help.

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Ok that's what I will do. Do I rotate the distributor and the cap or just the cap?

Hey, it's all good. That's why we're. But when you have #1 on TDC are you sure it's on compression stroke not exhaust? Know what I'm talking about?

That was wrong I took down. With wires attached rotating the cap will move it 180.


I know what you are talking about but not really sure how to know which one it is. If I rotate the motor by hand one more full time around do you think that the rotor will come around to the #1 position and then all I might have to do is change my wires around?

That was wrong I took down. With wires attached rotating the cap will move it 180. Don't take the distributor out to rotate unless you had it out...then you might have put it back in 180 off. But If you only had cap off, just do cap

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I have never had the distributor out but my brother changed the cap and rotor and it has never run right since! So in review I need to have it on tdc with rotor pointing at the #1 hole and then put the cap on so it matches the pic you sent me then put the wires back on starting with #1 pointing at the #1 hole and go in order clockwise from there.

Yes..before rotating cap try that. Rotate engine to where #1 goes down and comes back up...and I bet it will point to #1 as shown on the Haynes pic. If so, you were timing it from TDC on exhaust but I don't see how it would run at all...must have been really rough

Yes. That's it. He probably put the cap on wrong. They will clip on either way.

One way to tell is take out spark plug and have a helper bump the engine over with starter. Put you finger on spark plug hole, and when you feel compression, it's coming up in compression. If you feel nothing, the exhaust valve is open on exhaust stroke. I have even gone so far as take off valve cover and watch to see when both valves are closed. Hopefully you don't have to go that far

Just thinking one more thing. If he changed the cap, might not have put wires back on right...and you need to check each one is going to correct cylinder from cap


I did trace each wire and those are all good so I am pretty sure it is just the cap. I will check it as soon as I get home and then get back to you. Thank you very very much! This has been going on for a month or better! But think we are on it know!

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Please do let me know. Best of luck my friend


Hey so I went home and checked and sure enough the cap latches were 180 out. But upon further checking I found out that the cap only goes on one way so therefore I would have to guess that the distributor was 180 out. So I had my wife help me get it to tdc on a compression stoke then I turn the distributor and lined the rotor up on #1 and then changed the wires so that they follow the firing order just like the Hayes manual said. I retimed it using a light and put it at 8 btdc. The end result it still ran horrible! It will not rev at all. It will idle rough but not rev. The only way I can get it to run decent is to turn the timing all the way counter clockwise until it starts to die then turn it back just a little. It will run decent here and it has decent power but seems to run very rich. I can drive it now which is a vast improvement but something is not right.

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Well crapola. Ok,I went looking more, and there is a wire that is supposed to be disconnected when timing. Copied and pasted: "It's not unusal to see the ignition timing off by 20 to 30 degrees when this wire is still connected" They call it the engine control switch, so the ECU is not "Fighting" your movement of the distributor trying to set the base timing. Have a look at this:


I read that other forum. Boy that sure sounds like what I am experiencing. When I timed it I never disconnected any wires. The only info I could find online was to install a jumper in the ECU port under the dash between A and B and supposedly this would bypass the ECU but I don't think it worked! A local mechanic said it sounds like my ECU might be out but I don't know if I totally trust his input. Do you have a thought on that?

So then you have been advancing the timing until it almost dies. The rotor turns in a clockwise direction so to advance the timing you turn the body of the distributor counter clockwise, and to retard the timing you turn the body clockwise. I have looked at so many forums and guys are fighting about this, which way does what. But one way to remember is turn the distributor with rotation of rotor to retard and against rotation to advance..


You know to a hundred percent honest I cant remember which way I have to turn it but I do know that by looking at the marks on the timing tab the way I get it to run is to move the direction that is btdc until it dies then turn it back from there.. If memory serves me correctly. But I do know that it is the same as the other forum in that it is about 20 to 30 off before it will even run ok.

I don't know how much influence the ECU even has on an '86. I have nothing to compare it to because the two vehicles I own, my truck does not even have a computer and my Corolla the timing is controlled entirely by the ECU from the cam and crank position sensors, MAF, and on, it's not adjustable. Man, this is one I wish I could be there

I'm beginning to think about coil.


I don't know much about it why the coil? would the truck run at all if the coil were bad?

No, if the coil was completely dead it would not run at all. But they can get weak, a coil is a step-up transformer. There is a way to do a low-tech test..take off a spark plug wire and stick a phillips screwdriver in end that goes to plug. Get the wife or helper to start, or even crank it over and hold the stem of screwdriver about ¼" or less from any good ground, real close but not touch. It should be a sharp, cobalt-blue arc. If the arc, or spark, is yellow that's a weak spark, not enough to properly ignite the fuel/air inside. That would indicate a weak coil. Man, I'm just tossing thoughts, thinking we need to go in a different direction. I've also given some thought to the running rich.... is it blowing black smoke? And it has occurred to me your catalytic convertor may be partially plugged. Like I say, going for a new perspective to get to the bottom of this. .


I am headed home now to check the timing the way the link showed me earlier and also I will check the coil. As for the running rich it just smells like rich exhaust but no smoke at all and it has no catalytic converter! Welcome to rural Idaho!

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Ahhhh.... I am in Calif. and we have so many emissions tests it's not funny. But I can tell you, these days the air is cleaner than when I grew up in the LA basin in the 60's. Anyway..fingers crossed.... .

One head is usually closer to the front of the engine. If not, one spark plug is definitely closer to the front of the engine. Cylinder 1 is the cylinder closest to the front of the engine. Just look. This method applies to just about all cars.

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