Spark table opinions

[kostelacd69]

Has anyone ever done a timing table like this one I have set up here? On old FI stuff we would lock the timing down at one point that it ran ok every where. On N/A stuff we would set up weights and springs to get the curve we wanted and also have vac advance for cruise. Now with the computer we can have the best of everything right? Set the timing lower for very high vacume areas and then creep it back up for cruise. Lower the timing as boost/load starts to come in. What do you guys think?

[ScarabEpic22]

There is no reason to lock timing or set it up where every RPM has the same spark value while tuning an EFI ride. We have much better control with PCMs vs old school stuff.

You need to redo your spark tables, I dont think that is going to end well. Also your Boost VE table has weird values and shouldnt plateau like it currently does.

Looks like you've already done AutoVE on your Main VE table, now go back to the same spark tables you used for that and AutoVE the Boost VE table. Then get on a dyno and work the spark out.

[kostelacd69]

Yeah I had to stop tuning on it because I am currently over seas. I was just playing around with the timing while I was sitting here, just trying to get some thoughts. How would you set up your timiing table? The stock tables suck. There is no reason for negitive timing other than emision reasons. The reason the boost VE table looks that way is so that if anything happens and it goes into an area that I have not tuned it will go extremely rich.

[ScarabEpic22]

Ah gotcha, first off what engine setup is this, a stock 5.3 with some sort of FI. What internals, heads/cam/etc?

No reason for negative timing Id agree, but you're going to be better off starting with them plus a few degrees and tune it properly N/A. Once you get the spark tables dialed in, then you can get into boost and have the COS pull the proper amount of timing.

Understand about the Boost VE table, just make sure you dont run it that way all the time ha!

[kostelacd69]

402ci, Custom made cam, Dart Pro1 225 with some work done on them, Custom Race manifold setup with a GT4508R. 4L80E trans 5300lbs Silverado. I took it out once after putting the new turbo on and ran it twice just to get some rough VE numbers and it ran a 12.02 at 10lbs. That is slow, but with my timing table not being where I want it and Boost VE table not set yet I have to deal with it. So I started this whole tune with a stock timing table. Those table are great when they were designed for a stock 5.3 or 6.0 or what ever that is going to run good (not Great), and passed all federal crap. After spending hours and hours on changing all the numbers little by little, there was no flow to the timing table. So I decieded to do something like what I have posted. I dont think that it will end up "bad". How would you set yours up. If the tune I posted what would you change? Look through the whole thing if you have time and let me know what you think. I have my boost timing table setup to pull 1% for 1psi. The end result being 10 degrees and 10-11 psi. The motor is setup at 9.3 to 1 CR.

[SSpdDmon]

Nooo! Don't run that timing table. LOL Try starting from a '99 F-Body timing map for your 402. You'll need to adjust the timing down at WOT so that you're seeing 15* at full boost, 16~17* at moderate boost, and ease it on into the stock timing map. Your low airflow timing should be highest (as this is where vacuum should be greater) and decrease as airflow increases. See my example below from my D1SC LS1 car (7psi). Granted, I run a little more timing down low (meaning lower RPM, higher airflow - you'll see the "hump") because boost doesn't come on instantly. But, you should get the idea...

[kostelacd69]

So what do you think of this one. I have been playing with this table too. When I get home and get to log it and tune it I will get the tune better but I think this should be a good starting point. You seem to be a guru on this stuff, you have helped me out more than one time. I have been useing this for 2-3 years but my no means a bad ass with it lol. What do you think of this tune? I have read the idle tutorial more than once lol and have tried to apply it to what I have here. What do you think?

[SSpdDmon]

Please post the stock tune as well. I would like to use it as a comparison to see everything you changed.

[kostelacd69]

Hmmm stock tune? You mean from the very begining with the stock OS?

[kostelacd69]

This one will work I think.

[SSpdDmon]

Here's my crack at it. I'm assuming you've got a 2 or 3 bar map sensor and the A0010 will pull timing as you approach 10psi (MAP = atmospheric + 69kPa = ~170kPa @ sea level). If that's true, this should put you close to 14* at full boost. If it works out so the knock sensors are happy, I'd hop on a dyno and slowly add boost timing in A0010 until it stops making power while making sure AFR's are just under 12:1.

[kostelacd69]

Ok I will give that a shot when I get home in 2 weeks :)

[kostelacd69]

So I have to ask this, I can never get a good answer. What does the things in the Dynamic folder do???? Things like stomp, Impact, and evaporation do? Does that have anything to do with start up or if your siting in the drive way and floor it does it make it rev fast and come down off the rpms faster?

[ScarabEpic22]

No, it has to do with how the PCM calculates when to open/close the injectors.

[joecar]

So I have to ask this, I can never get a good answer. What does the things in the Dynamic folder do???? Things like stomp, Impact, and evaporation do? Does that have anything to do with start up or if your siting in the drive way and floor it does it make it rev fast and come down off the rpms faster?My very simple-minded understanding:

some of the injected fuel always hits the walls of the port on the heads, i.e. it wets the wall;

when manifold vacuum is high (i.e. MAP is low) (e.g during idle), fuel evaporates more quickly from the wall (and increases AFR);

when manifold vacuum is low (i.e. MAP is high) (e.g. during WOT), fuel evaporates more slowly from the wall (AFR stays more constant);

[ have I got that the right way around...? ]

Those tables are used to define to the PCM how the fuel wets the wall and how it evaporates from it; by knowing the rate of wetting/evaporation, the PCM can better control the amount of fuel sprayed by injectors.

[kostelacd69]

Oh got cha. So then we dont mess with those? Seems how I dont have any info on how fast or slow certane fuels evaporate under specific pressures and temperatures.

[kostelacd69]

certain

[joecar]

You can mess with those, but you have to control all the conditions, and make small/careful changes, those tables fix some transient AFR spikes that can't be fixed otherwise.

[kostelacd69]

Oh ok cool. So how do you go about make the rpm's come down faster after a P/N wot? Just wondering.

[joecar]

May have to look at throttle follower and/or throttle cracker... my knowledge is thin in this area (but am willing to learn) :doh2:

[kostelacd69]

Well if anyone has any help with that, that would be great.

[SSpdDmon]

May have to look at throttle follower and/or throttle cracker... my knowledge is thin in this area (but am willing to learn) :doh2:

Throttle follower would be where you start. Throttle cracker is MPH referenced and usually disabled under 2mph.