DIYPNP Spark advance basemap for boost
 

I've tried searching extensively and have not been able to figure this out for whatever reason.

I have a DIYPNP that I've actually been running in my boosted 95 Miata for the last 250 miles during break-in. Currently have a rebuilt 1.8, BP-T cams, IHI RHF5 (MSM) turbo running at 7psi, COPS, and 460cc injectors. I set the trigger angle offset at 8.00 degrees to get it timed to 10 deg base.

I had prior experience in tuning with eCtune and Crome, both of which have a feature that automatically retards timing a specified amount per lb of boost. I'll admit that my math is f**kin horrible so my first basemap that I've been tuning with had 2.5 degrees pulled per 20KPA above 100KPA. Well, it's been running seemingly fine (I haven't heard any hints of detonation), but last night while diagnosing my idle issues I realized that this still might be too far advanced so another attempt was made to figure out the best safe starting point. Behold my new timing map attached with 1.25 deg timing pulled per PSI or 3.62 degrees per 20KPA (20KPA = 2.9PSI * 1.25 retard = 3.62 deg pulled per row).

Someone please tell me I'm an idiot - because this just doesn't look right. I've tried searching extensively for ignition tables for similar setups, but can't seem to find what I'm looking for.

EDIT: And then it dawned on me that there's no need to pull an additional 1.25 degrees per lb since it's already accounted for in the timing table......wow, that was a moment.

Just to be safe I took an extra 10% of timing from the boost section by multiplying by .9. That should work for now...will keep my detcan handy anyway.

that's awful.

youre retarding over 10 degrees just as you enter boost. those numbers are the final timing angle numbers.


should look more like this:

http://www.miataforumz.com/attachmen...1&d=1335970263

Nope.

copy the above i posted and continue on with life?

Nope.

If you're worried, take about 5 to 7deg off Brain's timing above 100kPa and start from there.

Would 10ATDC do anything other than melt exhaust bits?

Guy on the dyno told me that anything shallower than about 7deg before TDC and you run the risk of not sparking off a majority of the mix. The flame front isn't traveling fast enough even to keep up with the speed of the piston by the time the exhaust valve opens. So, the mix continues to burn in the exhaust overheating your turbo turbine housing, seals and wheel and frying/plugging your cat. This would also likely torch your exhaust valves, which is a surface area to thickness and volume thing. The car will run like a pooch in this situation and it would probably come on fairly rapidly. At some point, it would act just like hitting the rev limiter. So, you might not notice except when viewing a datalog of the event.

would make sense I have the rev limiter pull timing out, and there is a noticeable drop in power output