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

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Originally Posted by 1project2many

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.

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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....

I'm running quite a lot more timing on my truck than the stock OBD2 Vortec tables. More than stock TBI tables too. Mine is actually a LT1/6spd Camaro table with a few degrees pulled out here & there.

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Originally Posted by pmkls1

Awesome !!! I've been wanting to see these tables for a long time now ! I'm curious about a couple values that you would have to be able to see some of the other parameters the PCM/VCM uses to calculate the "total" or "actual" timing. I would like to see what the typical timing value is at idle and what the total timing advance looks like at WOT throughout the RPM range. The way that I have the timing parameters set in my 7427 PCM is that there is no advance added while in PE. So, when looking at the open throttle timing table, the values in the 85-100kpa range reflect the total timing. Overall, the timing tables that I am using currently are surprisingly similar to these tables. Thanks for putting these up for people to see. I know that at least for me, the most difficult aspect of tuning after swapping in the vortec was the timing tables. Vortec heads are so sensitive to timing curves and are a bit different than traditional cast iron heads so they can be a challenge.

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Well I'm late coming in the discussion maybe but thought I'd add.... I'm running a 350 with flat-top pistons and vortec heads here in Austin, Tex. and with compression gauge in I get exactly 10:1 when I crank her over. Cam is Comp's XE-250H, 18mm Hg vacuum, hi-Torque but dies off 4500 rpm but I don't care cuz its in a 67 K-20 with 4:55's so I'm restricted to bottom end only anyhow with the SM-420 so my focus is on torque in 1500-4500 range. My contribution is that my setup won't take more than 7 deg of initial adv. Even at 7 it has a hard time strtup cranking in the heat after I come out of a store or something when its 100 deg outside. I think its the 10:1 that prevents me from doing 10 deg. initial adv. with my cam like lots of you all write with yours. I guess I need to back initial down to 6, and put about 26 degrees into the weights in the distr. somehow so I can have about 32 deg at WOT but there's no way in heck this motor would ever take 10 deg initial adv with that cam, them pistons, and those heads

You are sort of comparing apples to oranges Quaff. It sounds like you are running a conventional distributor that isn't computer controlled. I am assuming that you are probably running a typical HEI dizzy. The initial advance is a little different with a computer controlled distributor. But, before even getting into details with the timing there are a couple of other items I'd like to address.

You say that you get 10:1 with a compression gauge when cranking it over and that has me a bit confused. I'm not aware of a compression gauge that will measure compression ratio so I'm curious as to what you meant exactly. Typical flat-tops will average around the 10:1 range with vortec heads, though. But, that isn't really aggressive though as a stock L31 vortec runs 9.4:1 compression. Your cam is also fairly close to the stock L31 cam with a modest increase in lift and duration and very similar LSA and centerlines. It is an excellent cam grind for what you are running, but it isn't very aggressive by any means.

I also have a thought on your starter as well. Are you running an old-school small block starter ? If so you may want to consider a gear reduction starter. The stock vortec engines used a gear reduction starter, but I believe it was mainly for weight savings and compact size. Those starters are a bit pricey and not super special, but a typical aftermarket high torque mini-starter runs a little over $100 and is a good investment. If you only have a slow crank with more initial advance I don't think that the starter is an issue, but I would still be wary of the starter if you are running an old-school one.

Hi their guys,

I`m new to this forum, and didn`t yet find out my way around it. I wonder if you can help me, or direct me where to make a thread, in order to get some help.

I have a project with my Chevy 5.7 silverado 1990. I`m kind of restorating it, with additional upgrates. So wat i did is, i fully rebuild the engine, sandblasted and painted GM orange, installed KB flat top hypereutectic pistons, and comp cam 08-467-8. And as final i have made a vortec heads conversion, living the vortec manifold and injectors CFSI, installing the PCM Black box, and joining the two wirings together, in cabin is old and underhood is from vortec. So, now, the truck starts and works, but the problem is it gives me 20 degrees oftiming, and misfires. I took the car to a programmer, he unsoldered the chip and soldered an addapter for the chip, so it can be taken off easialy, reprogrammed it, and played with the ignition timer. When he gave me the car back, it had a P1345 stands for timing poins of crank and cam are off, said that have to adjust that and it will work fine. After checking all the marks and setting back the ignition timing (the marks were ok), the fault dissapeared and the engine light whent off. I have contacted him and said that it has to be adjusted through PCM black box, after reading alot of forums and projects, i think i`m right. Couldsomeone help me with this problem, any help is appreciated!!! Thanks in advance.

Ow, and one more thing, i havent yet conected the gear box wires to the PCM, want to do it from dashboard, not directly from the gearbox, but dont know yet to what pins in PCM and what to connect. Haven`t yet found the info. any help would be grate on that topic as well.

Thank you!

Not certain if I should try to resurrect this thread or add to my own but im interested in and willing to help get these timing tables figured out. I also use EFILive so I can snag a stock tune from the trucks of several friends if need be. I guess I have two main questions to start. First off, the vortec timing table appears to have much more advance than tbi but when I go through all the adders\multipliers I suspect thats not the case. Also do other bins have a PID for actual timing advance while datalogging? I ask because I see no way to log this but i'm running my stock and rather uncommon 6299 ecm with $99. Just fyi im running a vortec headed 385 stroker with 10.2 static compression and a very short duration crower roller cam.

I think upgrading the 16146299 ECM to the 16197427 PCM would be good option. http://www.gearhead-efi.com/Fuel-Inj...Information-0D

The 1227747 TBI ECM has great support, and is almost identically wired like the 16146299.

dave w