How is my LJR even running?

Altonymous

Altonymous

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Joined
Nov 22, 2017
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52
Location
Clayton, NC, United States
So this weekend I decided to replace the radiator due to a leak... And while at it I figured I'd do the water pump as well since I've been having some hard starts when it was hot... And since I've gone that far I might as well pull the timing cover and check out the chain.

Anyway, here I am lining up the timing marks on the chain to see how everything looks make sure it's not skipped a tooth, and figure I'd check my OPDA alignment while at it.

When low and behold with the sprocket marks lined up my OPDA is 180 out.

Now I have been driving around with it like this for a long time. Runs good, okay gas mileage, occasionally I'll get a CEL with those hard starts; but if I clear it it doesn't come back until I have another hard start when it's hot.

I took some picks with my OPDA almost lined up and the sprocket marks are definitely not lined up. Check it out in the pictures. Seriously this thing runs, I just don't get it.

opda.jpgtiming-chain.jpg

I can tell you that I had to set the OPDA like this 'almost' aligned to get it to run and it's been bothering me a lot. I can also tell you I pulled a spark plugs and to ensure I was on the right stroke when doing this so as not to be 180 out when setting up the OPDA.

I'm really wondering if the PO did the timing on the wrong stroke and that's why I have to run the OPDA like I do?

What should I do at this point to make sure it's all setup right. At this point I don't feel like I can assume anything is correct.
 
05 Blue Unlimited said:
I'm afraid for you but it seems to me you need to set the timing correctly and go from there.
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Right now I'm thinking I pull the spark plug and find TDC, don't trust the sprockets at all and align them based on that. And once they are right OPDA should be easy.

I feel like the crankshaft sprocket is fine, but the camshaft sprocket is suspect to me.
 
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So I just triple verified that I'm on the compression stroke in the front plug by using Mr Blaines balloon trick method. That camshaft sprocket is 180 out.

So do I just pull the sprockets and put the new ones in pointing at each other, then fix the OPDA? Or do I need to do something else?
 
It’s amazing what the computer can correct isn’t it? I’ve been wrenching since before computer controls and prefer the later OBD2 systems. I get a kick out of the guys older than me that hate new cars. Now we have sensors that give us all the info. An engine still only takes three things to run. The only thing that’s changed is the way we control it.
 
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Could be way off here, it's been a minute (or 35 years), but doesn't the cam turn twice for every turn of the crank? Gear twice as big? Cam has to push valves open for in then out. That means 180 is the same as zero, right?

(I hope I'm not wrong, don't want to look completely stupid)
 
dudehitt said:
Could be way off here, it's been a minute (or 35 years), but doesn't the cam turn twice for every turn of the crank? Gear twice as big? Cam has to push valves open for in then out. That means 180 is the same as zero, right?

(I hope I'm not wrong, don't want to look completely stupid)
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It turns half for every turn of the crank. That's how it gets 180 out from the crank. Half for the exhaust stroke and the other half for the compression. Which is why I had to turn it over multiple times to verify that I was on the compression. As MrBlaine also stated.. at the top of the exhaust stroke there's a small push of air.. but if you keep turning it will start sucking air. The compression stroke just pushes air the entire time.
 
Altonymous said:
It turns half for every turn of the crank. That's how it gets 180 out from the crank. Half for the exhaust stroke and the other half for the compression. Which is why I had to turn it over multiple times to verify that I was on the compression. As MrBlaine also stated.. at the top of the exhaust stroke there's a small push of air.. but if you keep turning it will start sucking air. The compression stroke just pushes air the entire time.
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You are correct. I’ve always just put my finger over the number one spark plug hole and used a remote start button. Once you find TDC set the balancer mark to zero. It shouldn’t be too far off after you blow your finger out of the hole.
 
I might be missing something here but pretty sure your engine won't run if the timing is 180 degrees out. The posted picture look like you are not aligning the timing mark on your camshaft sprocket/crankshaft correctly. I'm pretty sure you should turn the crankshaft until the timing mark on the camshaft sprocket is facing down and the crankshaft is facing up and align with each other. The posted picture show the timing mark on the camshaft sprocket on the top which would show your timing 180 degrees out. See attached.

IMG_2706.PNG
 
por212 said:
I might be missing something here but pretty sure your engine won't run if the timing is 180 degrees out. The posted picture look like you are not aligning the timing mark on your camshaft sprocket/crankshaft correctly. I'm pretty sure you should turn the crankshaft until the timing mark on the camshaft sprocket is facing down and the crankshaft is facing up and align with each other. The posted picture show the timing mark on the camshaft sprocket on the top which would show your timing 180 degrees out. See attached.

View attachment 87406
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I haven't done anything to it... This is how it was done by the PO.... and it runs. It is 180 out. I've confirmed that.
 
Altonymous said:
So I just triple verified that I'm on the compression stroke in the front plug by using Mr Blaines balloon trick method. That camshaft sprocket is 180 out
Click to expand...

It really is not possible to have the cam sprocket 180 out. It only fits on the cam 1 way. And the position of the cam (actually the valves controlled by the cam) determines which cylinder is on compression when in relation to the crank. So unless your cam was ground 180 out, your cam can't really be 180 out.

It seems pretty clear that your OPDA that is 180 out and others have done the same and their engines also run. My guess is if you set your OPDA correctly, your codes will probably stop being thrown. Be brave. Do it!

For spark, it's no surprise that the engine runs with the OPDA 180 out. The coil pack has only 3 coils for 6 cylinders. A spark gets fired in 2 cylinders by each coil at each firing. One cylinder is on compression. The other is on exhaust. Many multi-cylinder motorcycles use a similar system with 1 coil firing 2 paired cylinders. So with the OPDA 180 out, the cylinder that should be on compression (based on OPDA position) is on exhaust while the one that should be on exhaust is on compression. The coil still fires and the one on compression goes boom.

What I'm less clear on is how the port fuel injection can work correctly with the OPDA 180 out. Seems like the wrong injector would be firing each time. Maybe that is happening but the fuel just sits there waiting for the valve to open on the next crank rotation. Someone else here probably knows.

In any case, your jeep is throwing codes intermittently. Your timing is clearly off. Fix the timing and see what happens. If you're really concerned that the current setup is better than having it correct, put some marks on the OPDA so you can set it back to how it is now if things go south.
 
g.hayduke said:
It really is not possible to have the cam sprocket 180 out. It only fits on the cam 1 way. And the position of the cam (actually the valves controlled by the cam) determines which cylinder is on compression when in relation to the crank. So unless your cam was ground 180 out, your cam can't really be 180 out.

It seems pretty clear that your OPDA that is 180 out and others have done the same and their engines also run. My guess is if you set your OPDA correctly, your codes will probably stop being thrown. Be brave. Do it!

For spark, it's no surprise that the engine runs with the OPDA 180 out. The coil pack has only 3 coils for 6 cylinders. A spark gets fired in 2 cylinders by each coil at each firing. One cylinder is on compression. The other is on exhaust. Many multi-cylinder motorcycles use a similar system with 1 coil firing 2 paired cylinders. So with the OPDA 180 out, the cylinder that should be on compression (based on OPDA position) is on exhaust while the one that should be on exhaust is on compression. The coil still fires and the one on compression goes boom.

What I'm less clear on is how the port fuel injection can work correctly with the OPDA 180 out. Seems like the wrong injector would be firing each time. Maybe that is happening but the fuel just sits there waiting for the valve to open on the next crank rotation. Someone else here probably knows.

In any case, your jeep is throwing codes intermittently. Your timing is clearly off. Fix the timing and see what happens. If you're really concerned that the current setup is better than having it correct, put some marks on the OPDA so you can set it back to how it is now if things go south.
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Originally I had the OPDA 180 from where it is now.. and it won't run at all. I mean not at all. That's what caused me to verify TDC in the first place. Again... the OPDA is set based on the compression stroke of the front spark plug. I used both the finger over the hole to feel for compression and the balloon trick.

Either this camshaft sprocket has the marks backwards, would aftermarket do that, or I believe I need to pull the chain rotate the camshaft sprocket 180 degrees, then rotate the OPDA and everything would then be set to TDC.
 
If I was in your position, I would pull the valve cover so I can actually see the valves moving. As you rotate the crank, with the marks on the sprockets approaching being lined up, the valves on #1 should both be closed for roughly 1/2 turn on the crank before TDC and the valves on #6 should show the exhaust closing as the marks come close to alignment. If you see the opposite, either the cam or the cam sprocket was made 180 out which would be really bizarre.
 
Altonymous said:
I believe I need to pull the chain rotate the camshaft sprocket 180 degrees
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If you're at #1 TDC on compression and rotate the cam 180*, You'll no longer have #1 at TDC on compression. You'll have #6 at TDC on compression. Again, it's the position of the valves as controlled by the cam that determines which cylinder is at TDC on compression in relation to the crank position.
 
g.hayduke said:
If I was in your position, I would pull the valve cover so I can actually see the valves moving. As you rotate the crank, with the marks on the sprockets approaching being lined up, the valves on #1 should both be closed for roughly 1/2 turn on the crank before TDC and the valves on #6 should show the exhaust closing as the marks come close to alignment. If you see the opposite, either the cam or the cam sprocket was made 180 out which would be really bizarre.
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I found pictures of my Jeep at a shop with the motor being rebuilt.. so I am fairly confident they did it. I have also learned that my motor does fire the plugs twice.. so I think it's possible that the camshaft is 180 out and still running.. and of course the OPDA has to be aligned with it... Which I think would explain some of what I'm experiencing.. random misfires when hot.. engine always having hard starts after getting hot.. the timing cover being scorched...

I mean look at this timing cover...

timing-cover.jpg
 
dudehitt said:
If the cam and the opda are both 180 out then they match each other, right?
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Yes but it should be physically impossible for the cam to be 180 out. If it really is 180 out, something is very strange.

And it's hard to tell from the pics but it looks like it might not be exactly 180 out. Might be a tooth off from there.
 
g.hayduke said:
Yes but it should be physically impossible for the cam to be 180 out. If it really is 180 out, something is very strange.

And it's hard to tell from the pics but it looks like it might not be exactly 180 out. Might be a tooth off from there.
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Why do you think it would be physically impossible? We have spark on both strokes.. and the #1 and #6 cyls are paired.

As for it being off a tooth, yeah that's what I was thinking too.

dbbd1 said:
This is intriguing.


And, what's this balloon trick? Over the exhaust pipe?
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Balloon on a tube stuffed into the #1 cyl.. turn the crank watch it inflate... it's a visible indicator instead of a touch indicator.. helps me show others what's going on instead of just feeling it with my finger.
 
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