How to set ignition timing on OBS Yukon?

[99GMCZ71]

I changed intake gaskets on my 1999 OBS Yukon with the 5.7 this past weekend. Got a coolant leak somewhere, so several people suggested I start with the intake. PITA job, I might add, anyway, had to remove the distributor of course. I got it all back together and running, but can anybody tell me how to set the timing. On some of the other computer controlled vehicles I have worked on, there is usually a wire you disconnect (green plug), and then set the timing as normal. I can't find a "green plug" or a timing tab on this vehicle. If anybody knows what the timing should be, that would help too, I have no service manual for this truck. Thanks for any help!

[nhproxr]

The distributor can only go back in one spot. Computer controls the timing, there is no adjustment.

[99GMCZ71]

The distributor can only go back in one spot.  Computer controls the timing, there is no adjustment.

 

<{POST_SNAPBACK}>

 

 

No, the distributor can be put in several different ways. If you turn it to far one way or the other, the truck will not start. Trust me. It has a "static" timing of some sort. The computer can only compensate so much if the timing is off. Guess, I better get a service manual.

 

Update: On another GM forum they say it has to be hooked up to a computer to set the base timing as there is no connector to disconnect to use a timing light. Guess that is why there is no timing tab for the front balancer.

 

Thanks for the help

[Rookie]

MINE HAD A NOTCH ON IT SO IT ONLY WENT ONE WAY. JUST MY .02 SORRY ABOUT THE CAPS MY BUTTON IT STUCK.

[99GMCZ71]

When I put it back in the truck backfired through the intake. Turned the distributor a little one way and it fired right up. I marked it the way it came out, but when I put it back in, it must have been off just enough to cause the backfire. I really thought the computer would compensate if it was off a little, but I guess not. Hopefully, I got it close enough.

[Salmon Stalker]

The distributor can only go back in one spot.  Computer controls the timing, there is no adjustment.

 

<{POST_SNAPBACK}>

 

 

No, the distributor can be put in several different ways. If you turn it to far one way or the other, the truck will not start. Trust me. It has a "static" timing of some sort. The computer can only compensate so much if the timing is off. Guess, I better get a service manual.

 

Update: On another GM forum they say it has to be hooked up to a computer to set the base timing as there is no connector to disconnect to use a timing light. Guess that is why there is no timing tab for the front balancer.

 

Thanks for the help

 

<{POST_SNAPBACK}>

 

 

 

 

I just got done yesterday doing the exact same thing on my 1996 with a 5.7 engine. I have no idea whether your 1999 will be the same as mine, but here is what I experienced.

 

I initially had starting problems. I looked in my service manual under timing and it indicated computer controlled, no adjustments. It puzzled me. I went back and adjusted the timing just a little. Tried starting it about 3 times. After the 3rd time it started and ran rough. Another time and it was purring like a kitten. I'm assuming that the computer was working on the timing when I cranked it over.

 

Sidenote: I had to get it set somewhere close in order to get it to start easy because after I got it set right I moved the distributor a bit and it started hard again. Moved it back and it started easy.

 

Good luck... S/S

[Jeremy WI]

Get the engine to tdc on the compression stroke of cylinder #1. Remove distributor cap and see if the rotor is pointing to a "V" shaped pointer on the edge of the distributor base with a 8 on it(v8 engines), if it does not point at the 8, loosen distributor hold down and turn distributor so it does. If you can not get the rotor to point at the eight, remove distributor, align dimple in distributor gear(above or below roll pin that holds the gear on) with a line on the distributor base, you may also have to adjust the oil pump drive with a long screwdriver and flashlight. Once you get the rotor to line up with the 8 pointer, it should run good.

[Peter_C]

It is not the ignition timing that is being adjusted, you are adjusting the cam angle sensor in the distributer. The cam to crank relearn is very important, and requires a scanner.

[mcreyaufmiller]

I also did the IG on my 98. When I got done, because I had not marked the Distributor, I had to take it to the dealer to have the computer hooked up to it and the timing zero'd out. I called the service department, talked to the service manager and told them what was happening and they agreed to only charge me $35 and do it while I waited. It took 10 minutes and I was out the door. If it is not marked when you remove it, you MUST take it to a service place that has the computer to adjust the distributor. Sorry, I know this is not what you wanted to hear. You should have a engine code for misfire and you engine light on. I also thought I could time it the way I time carbed motors. I do this by ear and hit it almost every time. But it did not wirk for me this time. I learned the hard way.

[number9]

True-true....I had the intake gasket replaced in my truck and the Service Engine light kept coming on with code 3157 or something like that. Cam/crank position sensor. Had to take back to dealer and have them hook up to scan tool and zero out. They done it for free since they were the ones who did the intake work.