Engine detonation - what ignition advance is safe?
 

Hey all!

I'm almost done with tuning my VE table, and it's pretty nice as of right now. However, I'm not so sure about the timing. I'm using the timing maps that came with my MS, which I reckon are unchanged compared to the DIY 90-93 maps that diyautotune provides.

So here's the thing: I don't feel too safe with them. Even though I'm not turbo'd, I know the car keeps the ignition running from 10º to about 30º stock, but these maps put it running in the 16º to 37º area. That's an average 6º advance. I have since detuned the whole map by one degree. Here's my current map:

https://www.miataturbo.net/attachmen...ine=1336591256

Now, the reason I'm still worried is that I'm keeping the car running on conditions that might be a bit too lean for this map. In a rough way, here are some of the AFRs that I'm getting:

on idle: 14.9
while cruising (low revs): 14.2-14.8
while cruising (mid revs): 15-15.5
while driving well...erm.... enthusiastically: 13.5 to 14.5

I'm a bit more worried about the fact that I've been crusing slightly lean, not being compatible with the fact that my ignition is still pretty advanced.

Oh, another thing is that I set my ignition to retard 1º for every 5ºC that the IAT goes above 35ºC. That should keep me a bit safer too.

And I'm running on 95 octane pump gas (should be the same as your 90-91 octane over there in the USA).

So, what do you guys think? I want to make sure I'm safe at least until I get a knock sensor thingy, or some det cans!

you can add about 5-6 everywhere in boost and be fine. everything else is fine.

There is no boost goin on here.

http://www.miataturbo.net/attachment...chmentid=20150

I don't know what thread this file is from but I found it very useful.
That ignition map is very safe but sacrifices a lot of power.

WOT AFRs should be 12.8-13.0 for a non-turbo car. Your 100kpa timing is pretty conservative as well - I would lift the 101kpa row by 3* across the board, and then blend it smoothly into the 55kpa row.

Boosted timing depends a lot on which turbo you have.

I'll sort out the boost timing later, when I get a turbo. Eventually I'll be pointing at a small turbo (GT20 maybe?) for a low pressure build, and all those lines will have to be redone for more precision eventually. What I'm more worried about now, is the cruising (particularly in the 84kPa mark, where the car seems to be most of the time when picking up speed) part of the map. Detonation really freaks me out lol.

I don't suppose there's a map somewhere from the stock ECU of the 1.6? I know I saw some 1.8 maps around, that someone stimmed off the stock ECU, but no such luck in finding a 1.6 map. Only the base advance times.

Gee, thanks a bunch for that file you posted! Even though I got most of my targets fine for what I want, it's really nice to know the useable limits! You're awesome ;)

if you plan to run lean you want more advanced timing.
15.5 under cruise really isn't close to what I would consider lean
I've run before 16.5 \ 17 under cruise wtih 38 degrees of timing on my car.
Also I run into the 30s around 2000rpm down low considering I cruise around town there.