1998 Vortec Timing Table (Black Box Computer) Open / Closed Throttle ONLY!

[1project2many]

A-ha. No problem. You've had a lot of other stuff going on by the sounds of things.

FYI in a case where the info's hard to view I'm more than willing to send it offlist or in a different format.

[PJG1173]

I did the same thing several months ago. I didn't see that many spark tables, but who knows I looked at several .tun files and they all seemed different. I found that these tables ended up being very conservative for use in both my vortec headed motors and I ended up adding up to 12* in some areas. IDK might be from having aftermarket cam and port work. some of them had an optimal spark table which looked very aggressive though.

[dave w]

I did the same thing several months ago. I didn't see that many spark tables, but who knows I looked at several .tun files and they all seemed different. I found that these tables ended up being very conservative for use in both my vortec headed motors and I ended up adding up to 12* in some areas. IDK might be from having aftermarket cam and port work. some of them had an optimal spark table which looked very aggressive though.

I might have been more accurate if I had posted, a total of 21 spark parameters including spark tables. I think the spark table has to be tailored to the camshaft profile.

dave w

[pmkls1]

A-ha. No problem. You've had a lot of other stuff going on by the sounds of things.

FYI in a case where the info's hard to view I'm more than willing to send it offlist or in a different format.

I definitely have had a lot going on since I installed the engine. And as far as you sending info goes, I appreciate that and will keep it in mind for future reference. I didn't ask at the time because I didn't want to feel like I was begging someone to do all of the work for me. I wanted to be able to figure out things for myself, but I was having a hard time getting the ecm to do what I wanted. Ultimately, I had way too many issues to resolve before I could tune properly.

I did the same thing several months ago. I didn't see that many spark tables, but who knows I looked at several .tun files and they all seemed different. I found that these tables ended up being very conservative for use in both my vortec headed motors and I ended up adding up to 12* in some areas. IDK might be from having aftermarket cam and port work. some of them had an optimal spark table which looked very aggressive though.

Even a stock Vortec can handle a little more aggressive timing curve. I am running more total timing at WOT in my car without any issues, but the rest of the table is pretty similar. Once you open up the ports a little and throw in a more aggressive cam, you will more than likely end up with a much more aggressive table. It is my experience that Vortec heads like more aggressive timing in low-to-mid range loads, but will only want 32-34 degrees of max advance under heavy loads. I think that this is where people get confused when trying to tune the ignition curve on Vortec headed applications. Of course, you also have to consider that, while it is good to be able to observe what the factory ignition curve looks like, there is always room for improvement as the engineers usually stay a little conservative for numerous reasons.

[PJG1173]

Even a stock Vortec can handle a little more aggressive timing curve. I am running more total timing at WOT in my car without any issues, but the rest of the table is pretty similar. Once you open up the ports a little and throw in a more aggressive cam, you will more than likely end up with a much more aggressive table. It is my experience that Vortec heads like more aggressive timing in low-to-mid range loads, but will only want 32-34 degrees of max advance under heavy loads. I think that this is where people get confused when trying to tune the ignition curve on Vortec headed applications. Of course, you also have to consider that, while it is good to be able to observe what the factory ignition curve looks like, there is always room for improvement as the engineers usually stay a little conservative for numerous reasons.

I have experienced similar results with mine too. it likes alot of timing low but I'm only able to get 26* WOT without knock. I'm assuming this is because of the long duration of my cam. just goes back to every motor is different.

[1project2many]

it likes alot of timing low but I'm only able to get 26* WOT without knock. I'm assuming this is because of the long duration of my cam. just goes back to every motor is different.

Good heads with a fast burn chamber and tight quench will require less timing. People seem to think more is better when it comes to advance but the goal is to make the most power with the least amount of spark advance. When you start spark advance before TDC some of the energy from combustion is wasted as increasing pressure tries to prevent the piston from achieving TDC.

I'm still waiting for the day when in cylinder pressure sensors are part of the hotrodder's tuning arsenal.

[PJG1173]

Good heads with a fast burn chamber and tight quench will require less timing. People seem to think more is better when it comes to advance but the goal is to make the most power with the least amount of spark advance. When you start spark advance before TDC some of the energy from combustion is wasted as increasing pressure tries to prevent the piston from achieving TDC.

I'm still waiting for the day when in cylinder pressure sensors are part of the hotrodder's tuning arsenal.

All things being the same except the cam i run 33* on my other motor with about 10* less duration. I think the bigger duration cam gets more cylinder filling raising the dcr, and coupled with a tight quench and fast burn chambers is what
is reducing the need for timing.

[EagleMark]

I'm still waiting for the day when in cylinder pressure sensors are part of the hotrodder's tuning arsenal.

I priced them, it's not going to happen. Unless we all chip (Ha!) in to share one. One spark plug with sensor was in the $800 range.

[1project2many]

priced them, it's not going to happen.

The WBO2 was $2500 when I first started this game and now it's around 1/10th that price. GM uses active coil current and voltage detection to determine TDC on Ecotec engines and produce a cam sync pulse. And ion spark detecion circuitry can be adapted to measure cylinder pressure as well. We just need to get together and adapt or redesign some OEM circuitry.

[PJG1173]

The WBO2 was $2500 when I first started this game and now it's around 1/10th that price. GM uses active coil current and voltage detection to determine TDC on Ecotec engines and produce a cam sync pulse. And ion spark detecion circuitry can be adapted to measure cylinder pressure as well. We just need to get together and adapt or redesign some OEM circuitry.

Eh, sounds good. When yall figure it out write good instructions so us small brained people can figure it out.

[pmkls1]

The WBO2 was $2500 when I first started this game and now it's around 1/10th that price. GM uses active coil current and voltage detection to determine TDC on Ecotec engines and produce a cam sync pulse. And ion spark detecion circuitry can be adapted to measure cylinder pressure as well. We just need to get together and adapt or redesign some OEM circuitry.

I was aware of the ion spark detection capability of many late model coil designs and I believe the current and voltage detection was tied into that technology. But I had no clue that GM or any manufacturer for that matter was using it to determine TDC and produce a cam sync pulse. Of course, I admit that I only paid attention to a fraction of the training courses I took due to the sheer volume of courses it takes to acheive and maintain master tech status. For the time being, I still have access to GM's online database until my old employer decides that my training isn't beneficial to them anymore or until GM realizes that I am no longer employed there. But, as long as I have access, I can still easily obtain part numbers and schematics etc....