It's really just a big miata

[pdexta]

My megasquirt arrived this afternoon and I got the car running on it. It started up just like stock and it was running a touch lean. I added way too much fuel to it but it seems to be running good.

I'm hoping to get the tune dialed in this week and I'll try to get some virtual dyno logs. In Fort Myers, I had like 10 good straight flat roads that I felt comfortable datalogging pulls on. Now I can't think of one single flat straight road in Knoxville, should be interesting. Even I75 is crooked here.

[Jaysz28]

well that should prove challenging

but hills can help populate other map cells to help dial in the 'auto tune' portion

[pdexta]

I think the tuning part will be fine, it's just trying to get accurate virtual dyno numbers that will be tough. I feel like it'll read 300hp down hill and 100hp up hill, I guess I can always take the average, lol.

[Joe Morreale]

Are 3rd gear pulls worth anything? You have to be able to find a quarter mile of straight.

[pdexta]

I think 3rd gear will be fine, gearing is a good bit taller than a miata and it's not like I'm trying to get any official numbers, just curious to see what it's making. I actually found a spot that will work driving around today. It's not a place you want to hang out too long, but it's nice and flat with no intersecting traffic for .4 mi.

The car felt like it was breaking up a touch up top today. I swapped out spark plugs, but it didn't make a difference. The datalogs look like the MAP (manifold air pressure) values are jumping around a lot as well. I'm trying to convince myself it just looks that way because of the higher resolution when tuning an N/A car (my fuel/spark maps are scaled 30-110kpa vs 30-250kpa). I'm holding out hope it clears up with some more tuning, but I'm not too optimistic.

I took a bouncy MAP screenshot so you can see what I'm looking at. After 5500rpms MAP goes from pretty straight to pretty jiggly, but so does AFR (air/fuel ratio), that gives me some hope it will clear up. It's taking me a little bit to figure out how megasquirt is handling vtec and that's tripped me up a little. The 2 cam profiles are on different fuel/spark maps. I'm realizing now I eventually need to set vtec really high and tune the low cam, then set vtec really low and tune the high cam, figure out where power crosses and set that as my vtec engagement.

[Agent☣Orange]

Holy smokes! I'd need to be a rocket surgeon to do any of that!

[Joe Morreale]

Those map and afr graphs are as shaky as a drunken sailor's hands after a bad weekend. You're a ms guru, you'll figure it out. Have to before fi.

[pdexta]

I got a chance to read up on a shaky map reading and it sounds pretty common. There are filters that smooth it, but I may try another vacuum port first. The car is running great, just chasing little stuff; air intake temp correction map wasnt aggressive enough, and it was oscillating at a high idle briefly but I wasnt logging at the time. Hopefully the weekend gives me some decent weather for tuning.

[pdexta]

First attempt at the map filter failed.

Napa: You need help?
Me: I need a little filter that goes in a vacuum line.
Napa: What year?
Me: Its a universal part, that didn't come stock on the vehicle.
Napa: What year is the car?
Me: It wont pull up like that because it didnt come on the car.
Napa: So it's not a part for a vehicle then?
Me: I'll check somewhere else, thanks.

I'm going to try another manifold port first and if that doesn't help it seems like I'll be ordering it online.

[Agent☣Orange]

Hahaha! You'd be a better choice to run a NAPA than anyone there.