ElyasWolff

So I have a funny problem. My Miata runs fine on cold starts, starts easily and idles smoothly. But when I let it sit for 10 minutes and restart it does not want to start. When it does start it seems to idle fine, but when i rev it or drive it just dies. I was having a surging idle before and I zeroed out MAT correction, and moved my GM IAT to the throttlebody elbow, which seemed to fix that. I am stumped with this hot start thing, the car drives nicely when I fire it up from cold.

2004 MSM
MSPNP Pro
FF 640 injectors

Here is my .msq and a short datalog of hot start and the engine dieing.

Braineack

iTrader: (62)

your fuel map is too lean in that area. you're still hovering around 15-16-17 just as ASE and WUE roll off. there's a big hole in your VE table at idle areas -- that is very untypical. I'd also suggest using the ve idle table to fine tune your idle fueling.

also, turn on SPK: idle correction advance on your log -- look how much your ecu is moving timing around ot try to keep you on your idle targets. this is not good -- so i think your idle settings are bonkers.

also TURN OFF idle advance, your spark table is set to 22° at idle, but the idle advance correction is then bringing it to a solid 15°. Tune the spark table, and just use adaptive timing control for idle -- which is set WAY too aggressively.

ElyasWolff

Thanks Braineak. I made the changes you posted. I have more reading to do about the idle VE table before I try again.
My spark table is that advanced because that is what the DIYautotune basemap was. Should I keep it as is, with idle spark advance off. Then leave it, or bring the idle cells down to 15*? I just find it funny that if I warm up the car and drive around I dont have any problems. But after a restart I have the problems I mentioned. Either way I have more research and messing around to do.

Since I have MAT zeroed out after it is up to temp, IAT sensor heatsoak should not be related to the problem I am having correct?

ElyasWolff

Braineak,
I decided to look at the MSM basemap in the turbokitty link in your sig. It is very different than the DIYautotune basemap that they provide with my MSPNP PRO. Your VE table is not too different than the one I have with FF 640cc's but the Ignition map is very different. It is much more conservative. (I am running 8.5:1 CR) I am wondering why the DIYauto basemap for a stock MSM has over 10* more timing is many places than yours. Should I be concerned with what DIYautotune gave me and import your tables?

Matt Cramer

We tuned the spark map on our dyno on a stock example of a Mazdaspeed Miata. As long as the trigger angle is set correctly, it is a safe map unless you have made drastic changes to the cam or managed to boost VE dramatically without adding boost.

ElyasWolff

Thank you Matt, that alleviates the fear I had after looking at other people's MSM maps.