Bucking issue under load?

[FuzzFace2]

Hey Dave,

Are you SURE this is ignition related? I only ask because once I had this problem--in a 1973 chevy. Turned out the splines between the engine and trans were almost completely chewed through. Anyway, FWIW.

I am interested if this is a coil issue though.

I am almost 100% sure it is a spark issue as it feels like the motor shuts off & on really fast.

If it was a fuel issue it would spit & spudder as it ran out of gas in the carb.

If the tach moved faster when not getting power I then would know for sure it was a spark issue.

Bill & Gary gave me some things to check and I have a new coil to try but my gut is telling me pick up coil in the dist.

There is only 1 store around that has one in stock, Standard Product.

So after I do more checking I may go get it.

Dave ----

[FuzzFace2]

Well I am on the right path

#1 thru #6 left to right or top to bottom.

Changed the plugs, first 3 did not look bad and was thinking this is not it then got to #4 and WTH!

The motor never showed any signs of a miss up to this bucking but looking at #4 I dont know how that could be?

Took it for a test drive and the bucking is pretty much gone under load (empty but it did buck before the plug change).

Thing is I can feel a miss at steady throttle and trying to speed up in the higher gears, 4th and 4th OD.

I will let the motor cool down some and see if I can swap the plug wires from that plug to another and keep and eye on the 2 plugs to see if they show any signs of an issue.

I will also recheck the cap closer for spark tracing. But it is strange if it was cross firing I am not getting any back firing anywhere as you would think you would?

Dave ----

[AmericanSavage]

Well I am on the right path

#1 thru #6 left to right or top to bottom.

Changed the plugs, first 3 did not look bad and was thinking this is not it then got to #4 and WTH!

The motor never showed any signs of a miss up to this bucking but looking at #4 I dont know how that could be?

Took it for a test drive and the bucking is pretty much gone under load (empty but it did buck before the plug change).

Thing is I can feel a miss at steady throttle and trying to speed up in the higher gears, 4th and 4th OD.

I will let the motor cool down some and see if I can swap the plug wires from that plug to another and keep and eye on the 2 plugs to see if they show any signs of an issue.

I will also recheck the cap closer for spark tracing. But it is strange if it was cross firing I am not getting any back firing anywhere as you would think you would?

Dave ----

Dave,

That looks white and ash like—oil droplets?

[FuzzFace2]

Dave,

That looks white and ash like—oil droplets?

I hope not

I dont think it uses and oil between changes that I can think of.

Now when I first got it back on the road I had a lot of "milk shake" in the breather cap * hose to the air filter and the dip stick tube from condensation that I dont have now.

I also have not see any oil smoke out the tail pipe on start up or driving.

I know before I bought the truck it was only used around the small yard as it it did not have plates while he had it. Bought for his son as a project but son did not like it.

Before they told it was a farm truck so may not of been driven much then also?

So it could be with me putting miles on it it has "sealed it" by seating the rings better and getting it up to temp and staying there longer?

I am going to try and swap the plug wire with another plug if I can and see if it is a plug wire issue by checking the 2 plugs over time.

If the other plug dose the same I know it is a wire and not the hole.

Maybe I should try and find them plug adapters that we used back in the day when the motor burned oil and fouled the plugs

Dave ----

[Gary Lewis]

Dave,

That looks white and ash like—oil droplets?

I hope not

I dont think it uses and oil between changes that I can think of.

Now when I first got it back on the road I had a lot of "milk shake" in the breather cap * hose to the air filter and the dip stick tube from condensation that I dont have now.

I also have not see any oil smoke out the tail pipe on start up or driving.

I know before I bought the truck it was only used around the small yard as it it did not have plates while he had it. Bought for his son as a project but son did not like it.

Before they told it was a farm truck so may not of been driven much then also?

So it could be with me putting miles on it it has "sealed it" by seating the rings better and getting it up to temp and staying there longer?

I am going to try and swap the plug wire with another plug if I can and see if it is a plug wire issue by checking the 2 plugs over time.

If the other plug dose the same I know it is a wire and not the hole.

Maybe I should try and find them plug adapters that we used back in the day when the motor burned oil and fouled the plugs

Dave ----

Are you losing any coolant?

[FuzzFace2]

Are you losing any coolant?

It dose go low over time but I think it leaks from the NG vacuum valve for the no water flow when the HVAC is in vent.

The hose is too large for the valve and I am for ever tightening up the clamps.

I hope it is not what you are hinting to other wise

Also not getting any white / sweet smoke out the tail pipe or it has not gotten that bad yet?

I also dont remember or did not test that far, what hole had the miss when I first got the truck?

Also dont remember any of the plugs looking as bad as that one I pulled out.

Just a thought I am running coolant to heat the intake for cool / cold weather. I did use a freeze plug in the EGR port with sealer but wonder if the intake had a crack or bad casting and leaking coolant to that hole?

It is right at the area where the coolant is.

More to keep an eye on now

Dave ----

[Gary Lewis]

Are you losing any coolant?

It dose go low over time but I think it leaks from the NG vacuum valve for the no water flow when the HVAC is in vent.

The hose is too large for the valve and I am for ever tightening up the clamps.

I hope it is not what you are hinting to other wise

Also not getting any white / sweet smoke out the tail pipe or it has not gotten that bad yet?

I also dont remember or did not test that far, what hole had the miss when I first got the truck?

Also dont remember any of the plugs looking as bad as that one I pulled out.

Just a thought I am running coolant to heat the intake for cool / cold weather. I did use a freeze plug in the EGR port with sealer but wonder if the intake had a crack or bad casting and leaking coolant to that hole?

It is right at the area where the coolant is.

More to keep an eye on now

Dave ----

How many miles do you have on those plugs? If it is 5K or so then maybe it isn't a big issue?

[FuzzFace2]

How many miles do you have on those plugs? If it is 5K or so then maybe it isn't a big issue?

I would say 10K no more than 15K, 2 or 3 oil changes since the truck has been on the road.

Figure a little over 3K for each change so guess closer to 10K.

I swapped the plug wires with another hole so will keep eye on the 2 plugs.

I also pulled the plug end metal part out of the "good" wire so I forced it back in and fingers crossed it holds till I check plugs.

I also swapped out the coil, cleaned the connections, not that they were bad and that did not help.

You can feel it miss just cruising along and under even light load like pulling away from a light or stop sign.

I have rechecked the wires and plugs for the DSII system and they all look good.

I have even moved the wiring around with the motor idling and nothing.

Only thing that it can be now is the pick up coil. (maybe, see about the lean carb below)

All IGN tune up parts have been checked over as they only have maybe 10K on them.

Plugs have been changed and that was the biggest change. No more bucking but you can feel a miss when driving.

Carb has been swapped out with a new Ebay one.

It starts as fast as the old carb but may need to adjust the choke a little.

What I dont like is it runs vary lean based on my AFR gauge. Just normal driving holding speed it runs in the high 15's to mid 16's.

When I first started it after a cool down, motor still a little warm, fast idle came on but the AFR went so lean it blanked out when I first started driving it and you could feel it "lay down" lack power.

It was a little better after it got up to temp but it just dose not feel right.

I did readjust the idle speed & mix and will see if I can adjust the needle / jet richer as what I am feeling could be a lean miss fire now?

The fight goes on!

Dave ----

 

[Gary Lewis]

How many miles do you have on those plugs? If it is 5K or so then maybe it isn't a big issue?

I would say 10K no more than 15K, 2 or 3 oil changes since the truck has been on the road.

Figure a little over 3K for each change so guess closer to 10K.

I swapped the plug wires with another hole so will keep eye on the 2 plugs.

I also pulled the plug end metal part out of the "good" wire so I forced it back in and fingers crossed it holds till I check plugs.

I also swapped out the coil, cleaned the connections, not that they were bad and that did not help.

You can feel it miss just cruising along and under even light load like pulling away from a light or stop sign.

I have rechecked the wires and plugs for the DSII system and they all look good.

I have even moved the wiring around with the motor idling and nothing.

Only thing that it can be now is the pick up coil. (maybe, see about the lean carb below)

All IGN tune up parts have been checked over as they only have maybe 10K on them.

Plugs have been changed and that was the biggest change. No more bucking but you can feel a miss when driving.

Carb has been swapped out with a new Ebay one.

It starts as fast as the old carb but may need to adjust the choke a little.

What I dont like is it runs vary lean based on my AFR gauge. Just normal driving holding speed it runs in the high 15's to mid 16's.

When I first started it after a cool down, motor still a little warm, fast idle came on but the AFR went so lean it blanked out when I first started driving it and you could feel it "lay down" lack power.

It was a little better after it got up to temp but it just dose not feel right.

I did readjust the idle speed & mix and will see if I can adjust the needle / jet richer as what I am feeling could be a lean miss fire now?

The fight goes on!

Dave ----

So even after all of this, including replacing the plugs and swapping carbs, it is still missing?

If I remember correctly you have swapped the DS-II module. But you haven't replaced the pickup module. I think that would be my next step as it is the last of the common items.

As for "laying down", I do understand that when things go quite lean. But in my experience you don't get the bucking that you are experiencing.

 

[FuzzFace2]

So even after all of this, including replacing the plugs and swapping carbs, it is still missing?

If I remember correctly you have swapped the DS-II module. But you haven't replaced the pickup module. I think that would be my next step as it is the last of the common items.

As for "laying down", I do understand that when things go quite lean. But in my experience you don't get the bucking that you are experiencing.

I think I fixed 1 thing but caused another in trying to fix the bucking.

Here is my take:

Yes I did try a used DSII box, no change, everything else is in good shape.

Changed out the coil, no change. Swapped plug wires from bad plug with another plug and will keep an eye on the 2 plugs to see if the wire was the cause or ????

FYI I pulled the metal plug end out of the good wire when I did the swap so the wires will be replaced at some point.

In trying to fix the bucking I installed a Ebay carb I have had for a year or so.

It runs a lot leaner than the old carb and this may be the cause I have now that is more of a miss than bucking like before.

When I changed the plugs this stopped the bucking but now feel a miss just about all the time when driving.

Being the AFR is running in the mid 15's to mid 16.s and some times I have seen 17's I think I am feeling a lean miss. I want to richen up the needle and jet to see if that helps the miss.

If not I will pick up a pick up coil and change it out.

I had seen it posted some where a bed coil was causing a PITA and once out of the dist. he found a crack in the unit.

Still trying to fix this.

Dave ----