need help timing my 93 GT!

[Kool rider28]

my yukon has been running rough for the last couple of days. it missing and backfiring thru the intake. i have changed many parts( plugs, wire, rotor , cap, tps. my neighbor tells me to check my time and it is way off. when i pull the tan/black wire my base timing is 0. i turn the truck off reconnect the tan/black wire and my timing is off the scale high!! its not even close to the 12 mark on the scale.
i plan on ajusting it tomorrow but i dont know how and was hoping someone would chime in and help me out.

Thx
Kool

 

[SunlitComet]

do you shut engine off and then reconnect the wire and do the whole drive at part throttle thing to re-teach the computer afterwards.

 

[Kool rider28]

no i didn't. how long should i drive it. it is missing pretty bad. not sure how far i can drive it w/o messing something up.
so should i drive it at 1/4 with the wire disconnected also?
and what shoul dthe timming be for wire disconnected and connected?

 

[SunlitComet]

you drive it at part throttle and decelerate a few times. the wire is reconnected after the engine is shut off after adjustment. At wire disconnection the timing should be 0° tdc. with the wire connected is at the mercy of the ignition system and pcm.

 

[retorq]

If you pull that wire and timing is 0 then it's not way off, it's exactly where it should be. To be honest I don't even think you have a +/-12 mark on that stock balancer and timing mark setup. You would need a dial back timing light. You probably have something else wrong, loose spark plug, gaps are off, bad wire, loose wire ... I would say it could be hundreds or thousands of things but Sunlit will get mad at me again.

 

[SunlitComet]

Even a hundred things is a bit much.

 

[TORONTO 95 GT]

How about screwing up the firing order when changing wires?

 

[SunlitComet]

 

[Kool rider28]

that was it! some dummy has two wires crossed!!!
well she has almost a new ignition system now thx to me crossing those wires smh!
thx sun and 95 gt. if you guys where near id take you all for beer but since yall isnt here you go

 

[TORONTO 95 GT]

Glad you found it. I think we have all done it at some point.

Sunlit, thanks for posting the diagram.