97 5.7L Vortec, Timing advance connector

I have beat my head against the wall trying to find this elusive little !@#$!#@%!@#$!@# wire. Not under the glove box or dash. Not on the passenger firewall. I have looked behind the distibutor at the five different wiring bundles that run on the back of the motor and can't find it. Have looked under the brake booster and around the computer.

Called the local Chevrolet dealership. Mr. Goodwrench certified technician said, "That truck does not have that connector, just line the distributor cap up so it lines up with the motor with the plug wires out to either side." That was a direct quote.

So, guys and gals of the Vortec world. Does this truck have this connector that is disconnected to set the timing with a ScanTool to 0 degrees above 1200 rmp or does it not. And if not, then how in the name of all that is holy do you set the timing????? And if it does, where is it?????

Many thanks in advance in your help to abolish the p1345/p1351 codes.

Read this: http://www.automotiveforums.com/vbulletin/showthread.php?t=350633&highlight=vortec+timing

//2000CAYukon

Read this: http://www.automotiveforums.com/vbulletin/showthread.php?t=350633&highlight=vortec+timing

//2000CAYukon


Ok, I have read that thread and many more on this forum and still cannot verify if the 1997 vortec 5.7L has an EST wire, i.e. the brown wire w/black trace that the computer uses to advance the timing by whatever means.

That is my question and it is not answered in that thread, although that is where I gathered the 1200 rpm accuracy note I mentioned.

When I put the scantool on the truck and turn the dist. cap, the timing stays about the same, somewhere between 22-25 degrees no matter what direction or how much i turn it because the computer is compenstating. Though, at the extremes, the truck stumbles and dies.

I also understand that when you mention timing you are really referring to the cam/crank correlation and not actual timing.

I want to set the base with no computer interference or advancement. How is that accomplished?????

Going out on a limb here. Could it be your scan tool that's not letting you get into the "base" timing mode? Looked at my '98 manual and did not see a brown/black wire in the schematic. I know my Snap-On MT2500 will show actual timing and also let me get in a base timing mode that shows "0". This mode is referred in the manual as the "Camshaft Retard Offset" mode...........Steve

Ok, I have read that thread and many more on this forum and still cannot verify if the 1997 vortec 5.7L has an EST wire, i.e. the brown wire w/black trace that the computer uses to advance the timing by whatever means.

That is my question and it is not answered in that thread, although that is where I gathered the 1200 rpm accuracy note I mentioned.

When I put the scantool on the truck and turn the dist. cap, the timing stays about the same, somewhere between 22-25 degrees no matter what direction or how much i turn it because the computer is compenstating. Though, at the extremes, the truck stumbles and dies.

I also understand that when you mention timing you are really referring to the cam/crank correlation and not actual timing.

I want to set the base with no computer interference or advancement. How is that accomplished?????

95 is the last year with the EST wire; therefore, your 97 does not have it (unless someone installed a TBI engine in place of the Vortec).

Timing is completely controlled by the PCM. All you can do is set the cam retard which is what you need to do in order for your timing to be correct.

//2000CAYukon

95 is the last year with the EST wire; therefore, your 97 does not have it (unless someone installed a TBI engine in place of the Vortec).

Timing is completely controlled by the PCM. All you can do is set the cam retard which is what you need to do in order for your timing to be correct.

//2000CAYukon


Thank you very very much. So, just need to get scan tool set to base mode and set to zero degrees above 1200rpm.

Chilton's and Haynes both fail to mention that the EST is not on the 96-98 vortecs.

Will let ya know how is goes.

Thank you very very much. So, just need to get scan tool set to base mode and set to zero degrees above 1200rpm.

Chilton's and Haynes both fail to mention that the EST is not on the 96-98 vortecs.
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Chilton and Haynes fail......No surprise at all!

In the 97 distributor, there is no pickup anymore. Just the cam sensor and rotor.
The darn distributor is made out of plastic and the cap screws are loctited in so my distributor broke when I went to take the cap off.

Bob B

The timing on it is not adjustable.
Turning the dist does not change timing but it changes the camshaft retard.
The crankshaft sensor picks up TDC and tells the VCM/PCM/computer where it is and the commputer will adjust the timing.
The only thing you can adjust is the camshaft retard.
Which has nothing to do with the timing. Moving the dist does not affect timing but centers the rotor to fire at the dist cap plug wire plug.
And even some dist are not turnable.
Just get a scanner on it and check and make sure the camshaft retart is as close to 0 - 0 + as you can get it. Make sure it is not over 2 to 3 degrees - or + off.
And after turning dist to adjust it you have to get over 1000-1200 rpm for the pcm to adjust to the new setting.
MT :lol: :grinyes: :lol2:

I'm having a similar problem. My scanner won't show when I try and adjust my
Distributor. Another problem if anyone can help me with if possible. My truck runs fine in the morning, but in the afternoon when I'm on my way home it starts jerking real bad. Checked for misfires but it has none. If I punch it, it blows black smoke. I checked my plugs and right bank were all black. I've changed maf sensor and no change. Has anyone experienced this problem before?