Ignition problem 98 Yukon SOLVED!

Put your scanner on live data, monitor RPM while cranking. Might help. Shows CPS at least has output.
Also use Dielectric on connections/plug wires.

On ICM, you can unplug and put test light to ground testing white wire while cranking. Light should flash. Spark signal to ICM.

I shot the connections on the coil and ended up getting a new one, tests were in my Chilton manual. After I replaced the coil, a small adjustment to the distributor(more advance counter clockwise), it started and ran rough and gave me code 1345 crankshaft position/camshaft position correlation. I was going to try to rotate the distributor one tooth counter clockwise so I could capture the correct timing, but the cap was hitting the plastic intake manifold cover…! Frustrated, I packed up I’ll get to it in a couple days. I remember that when I initially set the timing, it was turned all the way in one direction trying to avoid hitting the manifold and fuel lines. Has anyone else dealt with this? Thanks again for your responses I hope the coil and the fuse did the trick. I’ll follow up with what I find with the timing adjustment.

To set the CMP, you aren’t re-stabbing the distributor or moving it to another tooth. Once it’s installed, loosen the hold-down bolt and twist the distributor by holding the cap until it’s at zero degrees per the scanner. Tighten the hold down and you’re set. Usually, that puts the cap screw tab nearly hitting the intake, but you’ll need a scanner to get it set correctly.

Yes I was thinking that it was a tooth off because it ran so rough after I did the re stab. I’ll retime it tomorrow I hope it works. So the code 1345 is because it’s not timed correctly?

In your scanner, look for something like CMP RETARD. Setting is "0" += 1degree above 1000 RPM.
As east302 mentioned - This should be verified first.
Update your scanner PIDS, I know the Torque app must be Torque pro and sometimes that doesn't work right without adjusting. Which APP are you using?

If you marked the body of the distributor and put it back in the same spot you can't be a tooth off or it wouldn't run unless you swung the body to a different spot.

redwing4900 said:

Yes I was thinking that it was a tooth off because it ran so rough after I did the re stab. I’ll retime it tomorrow I hope it works. So the code 1345 is because it’s not timed correctly?

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The P1345 will set, among other things, if the CMP Retard (cam/crankshaft correlation) isn’t adjusted following distributor removal.

If you moved the whole distributor up a tooth (you wouldn’t be the first to accidentally do that) then I’d try to put it back to the previous tooth and first position that matches your original marks. Then twist it until the tab hits the intake, tighten down the clamp and try to start it.

Here’s a worn out one at zero degrees, note that the tab nearly hits the upper intake:

That picture is exactly what I needed to see, thank you. I was working on the Yukon today moved the distributor back to it’s original position (1 tooth) i have the cap on there just like it’s pictured, and it started but it’s still not right. I’m getting a misfire code along with maf codes. I’ve changed 3 things so far: eng-i fuse, coil and cps. Someone mentioned that it must be ac delco but i have a master pro. Could this possibly be the problem? The engine sounds like i need more advance but it’s pegged for advance (counter clockwise) and that’s why i was trying to get creative by moving it one tooth over. When i retard the timing it won’t start. My read out tool doesn’t tell me what the timing is. I have to borrow a neighbor’s sensor to see where it’s at but i can tell it’s off. This is a picture of my old rotor that must have caused the corrosion mentioned before under the cap.
I’m stumped…thoughts?

By the way this was not an ac delco part the middle fried off and was laying in the distributor. Sounds like I’m answering my own question regarding ac delco versus cheaper doesn’t it I could change the cps back to the original one that was in there or get an AC delco cam position sensor and see if that does anything. My only issue with that is the timing is still wrong.

Do you mean the timing (controlled by the computer) or the CMP Retard (set using a scanner)? There’s no adjustment for the former and- unless you got really lucky- you’re off on the CMP if you don’t have a scanner to read it. But, it can be off up to 14-degrees or so without throwing the P1345 code.

The GM manual has the diagnostic tables for each code. I’d run through those before replacing any other parts. The manuals for a 98 can be downloaded here…


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