M20 Spark Blow Out

[SLEEPYDUB]

I'm having a lot of spark blow out and I want to see if anyone else on here has dealt with it, and what they did to remedy the problem.
M20 with 280/274 cam, Ms2, BPR7ES gapped to 0.020, MSD Wires, wasted spark GM DIS coils from a 3800 series with 3ms dwell, E85 fuel, low ignition timing till we figure this out at 16-17*, spark blow out starts around 15-20psi.

Any insight would be a big help
Thanks

[sayed ali]

What is your a/f ratio under load?

What map sensor are you using? Internal from ms or external?

[SLEEPYDUB]

AFR is between 11.0-12.0
Internal map sensor in MS

[sayed ali]

AFR is between 11.0-12.0
Internal map sensor in MS

I guess 11.0 is too rich & how many psi does the internal ms map support?

Just try to wire up a new external map (like GM 3 bar) and see, as i had a bad experience with internal map sensor once i exceed the certain psi that it supports, even 1 psi only more ..

[SLEEPYDUB]

3 bar.
11.0 was way too rich. Apparently E85 on M20 likes to run a bit leaner. We smoothed out the fuel map and added some timing and its running much smoother and the miss is gone. Up to 10psi so far with no issues, and the car pulls much harder now. We will hook up the 4port boost controller and start adding some boost.

[sayed ali]

3 bar.
11.0 was way too rich. Apparently E85 on M20 likes to run a bit leaner. We smoothed out the fuel map and added some timing and its running much smoother and the miss is gone. Up to 10psi so far with no issues, and the car pulls much harder now. We will hook up the 4port boost controller and start adding some boost.

Good to hear that, good luck ;)

[ForcedFirebird]

Not enough timing acts similar to spark blow out. I often find DIY tunes to be too conservative, or pull timing too abruptly when going vertical in the map.

[LowR3V'in]

^ do you have a link to what a proper timing map looks like?

[ForcedFirebird]

^ do you have a link to what a proper timing map looks like?

Since everyone uses different resolution or even base timig), it's hard to just say "this one" at a glance. As I posted earlier, start with a stock table and remove 2° for every 1psi (or ~7kpa) and "listen" to what the engine wants via finding MBT and/or using det cans. If you like for safety sake, go 3-4°, just keep in mind pulling 15° at 15psig isn't often needed.

The m20's never need a ton of timing to begin with, generally only make it to 30° before losing power, but more like 24-27° seems to be all they really need. Now remove ~1-2° per psig and you will be close to ~8-10° at 1bar.

First few pages of the e30t maps thread discussed it well...

http://www.e30tech.com/forum/showthread.php?t=33028&page=5

[doug.gardiner@gmail.com]

Interesting...

I have plans to turbo my dirty 30, but that is phase 3. Hoping that I can remember this for my days in tuning hell :)

[wat3rbug]

Subbed

Subbed as I would also like to know.