MicroSquirt.com read only forum (Jan.15,2018)

i've been working on the tune on my mustang, i happed to switch to the constants page and somehow my opening time was set 1.2ms and battery was .2, i switched them back to where they should be 1.0 and .1 and it ran like crap, i guess i have to retune it at these values? I switched the opening time to 1.1 and switched the battery to .2 and it ran better.

im also getting some sever "studdering" as soon as it hits boost, it feels like that it might be running too rich, im tuning with an LC-1 wideband which shows 11.0-11.3 on that gauge and in the datalogs. I also made a timing map instead of it locked in at 15, i went up to 17degrees in boost now and seems like it helped a little bit, seems like the studdering doesnt start till a bit later.

87vert wrote:i've been working on the tune on my mustang, i happed to switch to the constants page and somehow my opening time was set 1.2ms and battery was .2, i switched them back to where they should be 1.0 and .1 and it ran like crap, i guess i have to retune it at these values? I switched the opening time to 1.1 and switched the battery to .2 and it ran better.

Yes, the injector opening time is included in the tuning calculations. Changing your settings from 1.2 to 1.0 decreases the resulting pulsewidth by .2 ms. You're likely getting less fuel than previously.

87vert wrote:im also getting some severe "stuttering" as soon as it hits boost, it feels like that it might be running too rich, im tuning with an LC-1 wideband which shows 11.0-11.3 on that gauge and in the datalogs. I also made a timing map instead of it locked in at 15, i went up to 17degrees in boost now and seems like it helped a little bit, seems like the studdering doesnt start till a bit later.

I've never tuned a boosted vehicle, and I can't help much, but changing your timing with load and RPM is the norm... I would think a fixed ignition map would wreck a motor under boost. Don't you usualy start to retard ignition under boost, not advance? (showing my ignorance here!)

-Brian

Yeh you should take your 100kpa spark advance readings and then knock them down roughly 1 degree per psi boost 11:1 AFR shouldn`t cause stuttering, spark blowout could though (what are your plug gaps like, general ignition system?). I found when you go too low with the spark advance you just stop accelerating, not start stuttering.

Blowing out the spark is a function of spark strength, compression, VE and boost pressure (and probably a couple I missed). What I'm trying to say is it's highly engine-specific. You might want to entertain the notion of a stronger ignition system if it sounds like a misfire.

1 degree per psi is a tad more than most boosted setups I see. You might be giving up a lot of power and encountering high EGTs as a result.

plugs are 2 steps colder gapped at .30 (stock gap .54) running an MSD ignition box w/ msd coil, 9mm wires, (less than 1000miles) new cap/rotor,

i bumped the timing up a few more degrees and smoothed out the map and it feels better, it seems like that its only doing it at low boost, seems like once it hits 5psi or so it smooths out.

i can post a datalog tonight if anyone thinks that might help, i dont see anything abnormal with it thought,

it seems like it ran better when it was a bit leaner, maybe my wideband is reading off, i made sure to re-calibrate it after the car sat for 3months.