1998 yukon Mystery p0300 and rough idle still

[exp500]

Just a reminder- test CMP at around 1000-1200 RPM steady.
If your distributor gear or body is worn, CMP retard will move around enough to set codes. These work well for me many times.-

More Information for UNITED MOTOR PRODUCTS 9362

More Information for UNITED MOTOR PRODUCTS DCR820X

 

[OilBurner2003]

Just a reminder- test CMP at around 1000-1200 RPM steady.
If your distributor gear or body is worn, CMP retard will move around enough to set codes. These work well for me many times.-

More Information for UNITED MOTOR PRODUCTS 9362

More Information for UNITED MOTOR PRODUCTS DCR820X

Just got it all done. Couldn’t get 0. On the dot, it’s going between -1.0 or -0.1 looks like it didn’t solve my issue anyhow, all 8 Cylinders aren’t doing too hot. This is all before I even messed with the distributor haha

 

[OilBurner2003]

-2 to +2 is within spec, zero being optimal

Alright, I’m within spec now. I believe at least. No noticeable change unfortunately, so at least I know it’s correct now. Now I’m looking at history, and well. I’m lost. Yeah it feels like crap at idle, but all 8 cylinders? At least I have the ability to see this now. Cylinder two is especially unhappy…

 

[east302]

Just a reminder- test CMP at around 1000-1200 RPM steady.
If your distributor gear or body is worn, CMP retard will move around enough to set codes. These work well for me many times.-

More Information for UNITED MOTOR PRODUCTS 9362

More Information for UNITED MOTOR PRODUCTS DCR820X

I’d agree, wouldn’t hurt to pull it and see what the gear looks like. Misfire counts don’t appear to be localized, but continued operation may help spot a trend.

 

[OilBurner2003]

I’d agree, wouldn’t hurt to pull it and see what the gear looks like. Misfire counts don’t appear to be localized, but continued operation may help spot a trend.

To be clear, take the distributor out? Do I have to get it to top dead center, or can I just unbolt it and pull it out?

 

[east302]

No need to set to TDC, just don’t crank it while it’s out. Mark the distributor relative to the shaft/intake and rotor to housing. When it’s pulled, the rotor will rotate so mark where it ends up.

When you reinstall, line up the shaft/intake marks and put the rotor at your second mark. When it seats, it’ll turn and end up and your first mark.

Oil pump shaft will need to be turned with a long screwdriver to realign it with the distributor to get it to seat. It’s either really easy or stupidly annoying when I do it. Shine a light and look down in there and you’ll see how it has to align.



View attachment 385515

 

[OilBurner2003]

No need to set to TDC, just don’t crank it while it’s out. Mark the distributor relative to the shaft/intake and rotor to housing. When it’s pulled, the rotor will rotate so mark where it ends up.

When you reinstall, line up the shaft/intake marks and put the rotor at your second mark. When it seats, it’ll turn and end up and your first mark.

Oil pump shaft will need to be turned with a long screwdriver to realign it with the distributor to get it to seat. It’s either really easy or stupidly annoying when I do it. Shine a light and look down in there and you’ll see how it has to align.

View attachment 385517

View attachment 385515
View attachment 385516

Roger, I’ll get right on it.

 

[east302]

Forgot to mention, there’s a paper gasket between the distributor and intake. If it stays on the intake, best just leave it there. If it tears apart, they’re probably available locally. Best practice would be to replace it, though.

 

[OilBurner2003]

No need to set to TDC, just don’t crank it while it’s out. Mark the distributor relative to the shaft/intake and rotor to housing. When it’s pulled, the rotor will rotate so mark where it ends up.

When you reinstall, line up the shaft/intake marks and put the rotor at your second mark. When it seats, it’ll turn and end up and your first mark.

Oil pump shaft will need to be turned with a long screwdriver to realign it with the distributor to get it to seat. It’s either really easy or stupidly annoying when I do it. Shine a light and look down in there and you’ll see how it has to align.

View attachment 385517

View attachment 385515
View attachment 385516

Forgot to mention, there’s a paper gasket between the distributor and intake. If it stays on the intake, best just leave it there. If it tears apart, they’re probably available locally. Best practice would be to replace it, though.

View attachment 385518

I believe my gasket has burned away or the mechanic didn’t install one when this engine was built, I can’t see it. Probably explains the oil I saw trying to take it out. Here’s the distributor teeth and the shaft, I’m not sure what to look for so I took some pics.

 

[east302]

If the gears were real knife edged, that’d be a good indicator. Hard to say, maybe @exp500 or @OR VietVet would be able to give a better opinion.