when I first started tuning the VE tables I got them close as possible to 128 all was good. I then noticed I had some knock so I proceeded to take out spark advance where knock was occuring and before it. I basically went through the whol table and took out from 1 to 4 degress of advance. Now I re worked the VE values and basically have no knock present under any circumstance. I still get a few knock counts and some timing retardation but not unless I really hammer it. Anyway I have the feeling that even though I am not getting any knock and retardation the car feels a bit slower. Before when I was getting knock the ECM would pull out up to 7 deg of advance at certain points. So I thought maybe pulling out 2-4 degress in these spots I would avoid retardation all together. But maybe the knock sensor does a good job and I should maybe add some more timing back?? What is the go with this? Does the knock sensor protect the engine from knock well or am I better off leaving it as is and having no knock? Because I am thinking about adding some spark advance back where I took it out from and let the knock sensor take care of it. And pull out timing when needed. What do you guys think?

There are two ways to tune for timing, 1) tune to the limit of the octane, 2) min amount that keeps the engine happy.

There's a resent post with a link to discribing detonation, preignition that you want to read.

Obviously, if your racing #1 is what you want.
#2 gives alot more engine life, and allows for having room in the K/S calibration to allow for the ocassional bad tank of gas.

There's a huge difference in the two.

Grumpy, I think I found the post you were refering to and had a read of it. Just a bit confused on some parts.

What I am trying to figure out should I add a bit more fuel maybe with the injector constant and then I could add a bit more timing.

I have read your posts before and you have always said to have the injector constat to match the injectors.

I also have the PE spark tables zeroed out.


I have actually burnt back the original spark advance table from a 1992 Z28 original chip. I'll see if it makes the car faster when I hook up the scanner and do some test runs.

But like you say engine life is probably a greater priority then having a faster car by a couple tenths by adding a few degress of advance. Probably not even worth it.


The only thing I have noticed is that on the STOCK chip the VE tables kind of ge greater in value as the MAP increases. Since tuning my VE tables for 128 the ve tables do not really flow that smooth as the stock ones. There are spiked present in certain spots. But I am getting very close 128 across the board.

Detonation takes time.
This can mean a few things. ie, running too much timing in cruise, and then when you hammer it the chamber temps are high to begin with. That means more AE for cooling. I dunno way but 90% of the stuff I see, folks just don't ramp out the timing quick enough coming out of cruise mode.

MAFs read a false rich, when there's reversion present. So when you change the intake plumbing, you change the inherit tuning, change the cam, and you've done more to fubar the cal.. Trying to make an injector constant change to correct a reversion peoblem, IMO, just doesn't make sense.

Do what makes the engine happy, not what looks good to the human eye, the spikes are normal for some cars.

If you change the fuel, and still have some Knock counts, then it's a timing problem. The reverse is also true.
Often it's a combination of the two, and going too far can also get you into a knock problem.

Great post, Like you say when I tuned for no knock I basically took out plenty of spark adavnce from 1-5 degress across the board. Now the car gets hardly any knock. With the original setup I used ot get some and a bit more when hammering around up to 7 deg retardation. So I took out advance and now have no knock or very very little. Adjusted the VE in some cases to get back to 128 and all is pretty good.

Here in Australia we are lucky to get good quality fuel I only use 98 octane and the fact is with the stock spark adavce tables I am using on my MAP car converted to SD on the AUJP code I was getting knock and this was like I say on 98 ocatne fuel.


I'll try the stock advance tables and see how it fars, if I still get the same knock as I used to I'll just put back my edited spark advance tables and be done with it.

I guess if I want to go faster I need a bigger engine then the 305 and not stress the engine too much out with a few degrees of advance

Thanks for your help.