Timing , 01 blazer

[jstutz]

I bought a Ultragauge the other day. After hooking it up to the truck, it found it and everything is okay. My question is when i look at timing, it is saying it is advanced 30 deg. On my way to work today it fluctuated between 18 deg and 31 deg. This seems excessive. Has anyone else measured this and knows what it should be? The distributor has been out two different times for various reasons and im thinking it got installed a tooth off or something. Would it even run if it was actually 30 deg advanced?

 

[ARCOgraphite]

18-31 deg seems modest. A vacuum/mechanical curved dist on a low comp v6/v8 are often curved to run around 6-36 from WOT (no vacuum) to 36+ light throttle cruise (high vacuum). I dont recall but most modern engines have a separate ignition trigger and the dist is set to a nominal position so the rotor isnt too far from the terminals. If you are having problems you may want to try the NAPA alkyd rotor and cap vs. a most likely chinese knockoff DELCO. The NAPA premium rotr has a long tail on it to help prevent spart scatter on the crummy small cap dist used on the 4.3.

 

[jstutz]

Thanks ARCO, im not having any issues, i just saw the numbers and thought they were way off. It sounds like they are normal and i will stop worrying about it. Again thanks

 

[The_Eric]

What you're really after is the variance. I forget the exact name, but it is either ckp or cam variance. That is your base timing and it should be at 0*. The computer will handle all timing duties from that point.

 

[jstutz]

Originally Posted By: The_Eric
What you're really after is the variance. I forget the exact name, but it is either ckp or cam variance. That is your base timing and it should be at 0*. The computer will handle all timing duties from that point.


Is this in general or what the Ultragauge will display?

 

[The_Eric]

To be honest, I can't say what all your Ultragauge will show. It's not likely it will come to think of it. On the Snap On Modis scan tool we use at work, there is a special menu for it. The variance is completely different from the timing that you're seeing. It's the difference between the cam sensor (distributor) and crank sensor and like I said, that needs to be 0*.

The most I can say is to cruise through your scan tool's menu(s) and see if you can find it.

 

[mechtech2]

31 is conservative.
I would expect 10-35 as normal. Maybe more at cruise.

 

[disturban]

This is a 2001 OBDII GM vehicle, the reason why your timing is all over the place is it is computer controlled and also has torque management, torque management pulls timing under certain conditions such as when your transmission shifts gears and even when your air conditioner engages.

You can use EFI live or HP tuners to take all that torque management [censored] out of the tune and gain a lot of performance, if you do not have access to either program a custom tuner can do it for you, like waitformeperformance, blackbear or pcmforless, they can also bump the timing up because GM set the timing real lazy on Vortec 4.3 liter motors and a custom tune will really wake them up, I suggest waitformeperformance as they are the cheapest and have an outstanding reputation for tuning S10 trucks.

Some people will tell you to leave in a little torque management or your transmission will not last...this is wrong info! They put it in the transmission tune because they use low line pressure to achieve smooth shifts for soccer moms and old people, with the low line pressure comes clutch slippage. To prevent the motor from burning up clutches they programed in torque management to pull a butt load of timing at every shift, with a custom tune you can increase the transmission line pressure so the clutches lock up tighter and then take out all torque management will no ill effects...in fact some people report gaining almost a second in the 1/4 mile just removing the torque management, that is how bad it effects performance and it also effects gas mileage.