Hi
i have looked and looked for days so now i am hoping you all can help
i bought a 1998 GMC Yukon with a 5.7 it was running a little rough and it looks like someone swapped plugs wires and distributor
it is throwing the P1345 code
what i did was get the piston to TDC (verified with a screwdriver in the plug hole) and make sure the mark is aligned up with the pointer
pulled the cap and made sure it was pointing in the general direction of cyl 1 pulled it out and
stabbed it back and got it closer to the number 8 inside the distributor started, now it fires right up with no miss except for a little at idle but not like before where it was stumbling at start
but when i hook up the Tech2 its shows CMP -18 at 1000RPM ( i borrowed one from my buddy)
started over and same issue then i bought a distributor because i had no idea where that other came from
set it the same way making sure the rotor is pointing to the 8 inside the distributor and same issue
hook up the tech2, rev it a bit past 1000rmp and CMP -18 i also cleared the code and it comes right back, performed the crank learn function and it passed.
check the chain for play and nothing so now im stuck
i was going to remove the distributer lock and see if i can reduce the CMP or i can turn it backwards a tooth and see if that gets it closer

thanks

 

I loosened the clamp and reversed it to temp lock the distributor i then set up the tech 2 and turned the distributor clockwise and got the CMP to 0
i dont understand how it would be that far off but I'm going to clock it back a tooth and see what happens if worse comes to worse ill cut the clamp and set it where it needs to be
but i do not want to rig it that way

 

Distributor gear can be put on it's shaft 180 out. With 13 teeth, this moves the gear 1/2 tooth (1/2 of 27.7 degrees = 13.85 distributor degrees). That is one of the possibilities for Cam Sensor Retard reading off on adjacent teeth with distributor lock intact.

However, if you turn the distributor and lock it down, it's all the same!! As long as the distributor gear is not worn.....

 

should i unpin it and flip the gear drive? is a new distributor but both are aftermarket from the same vendor Dorman only the first one i did not install

thanks

 

If you can get one to cam sensor retard=0 - just lock it down and leave it there. Many people just replace the factory hold down with one from an older SBC.

 

I flipped the gear and with the lockdown clip it went from -18 to +10 then I cut the lockdown clip and turned the distributor to show CMP at 0 and tightened it up
reved it several times and it stayed at 0
I cleared the code and it never came back the test drive was smooth also I hope this helps someone out in the future.
Thanks for all your help LesMyer i appreciate it and will pay it foward
on to the next thing to fix on this truck

 

Glad to have helped.

 

is there a tool that can work to verify the timing .. all i have is a scan tool with live data