Possible to tune Megasquirt with wideband alone?
 

Hey guys, well recently I heard the remarks that a typical dyno tune will cost me from 800-2000 dollars. That's just...omg... Is it possible for me to conservatively tune in my car for 12 psi with a wideband 02 sensor. If possible, does anybody have any MSQ files running an IAT sensor with tuning for a Garrett GT2860RS with 460cc injectors on a 1997 Mazda Miata.

The MSNPNP timing map is pretty conservative, that would be something you can start with, just listen for knock. Then tune your afr's with the wideband. 80% of the forum tunes their cars on the street, just don't let it knock.

That's fuckin' retarded (not you, but it does take that long when you start from scratch). You REALLY need to learn about AUTOTUNE, DATALOGGING, and MEGALOGVIEWER VE table analysis and you'll be able to get yourself 90% there on your own.

Somebody will send you their fuel/spark MAP's that you can use for a baseline. I run a much smaller T25 or you could have mine. Then you need to dedicate a couple hours to teaching yourself about the 3 things I mentioned above. You need a VERY LONG straight road that you can get out on and just drive, with places every 10 miles or so that you can pull over and check your data.

Once you have a fairly flat AF curve at WOT, with good transition into boost at all RPM's, you might want to invest in an hour on the dyno. I spent an afternoon learing how the various "tune" things in MS worked, put 100 miles on it at all sorts of boost/RPM settings and got the thing running pretty good just using AUTOTUNE. Then on the dyno I datalogged each run, backing up the info with what the dyno instruments were saying, and ran the pulls through Megalogviewer while the car was cooling down... then made minor changes (mostly to SMOOTH out the fuel transitions from cel to cel) and it took 8 pulls to get everything where I wanted it.

And why isn't your location in your profile NEWB? Maybe somebody smart on MS local to you would volunteer to help you if they knew where you were!

If you pay more than $500 for a dyno tun you are getting ripped off. The dude that tuned mine normally charges $400 and he deals with cars that cost well over $100K on a daily basis.

Fuel can be tuned with just a wideband, but getting a perfect timing curve without a dyno is very difficult.

which is why i gotta get my ass down to DIY this spring

$900 is the cheapest I've found, one guy wanted $2000, and others refused to tune it. Others still were really awesome and let me know that if I had to change plugs or whatever, they were going to charge me an additional hour of labor. Even more exciting though, I only found 2 shops which did NOT insist on adjusting cold start and "checking my settings." Luckily I found a LS1 tuner who said to bring it in, work megasquirt, and he'll work the dyno for $400.

my guy charges me couple hundred bux... and he tunes vipers all day long

Yeah, my guy is an LSx dude as well. The domestic shops seem to be cheaper and do a better job that most of the import shops around here.

i street tuned my evo forever its actually better to tune a car on the street since the load conditions on a dyno are so different. im not familiar with MS but i am learning about it. i have been reading a lot about how people just listen for knock....dont these cars have a knock sensor? or has anyone ever installed one

Those guys simply don't want to do it. It's not that they can't though.
They're trying to run you off.

I've been watching the Megasquirt thing grow and am noticing a distinct lack of interest with most shops. Bottom line, since you can build one for under $300 and a 90% tune on the street with relative ease using the Datalogging and Autotune with the included free and easy-to-use software, why even go to a dyno? That coupled with the fact that you can just ask for a map through a forum and have somebody ship you a 95% tune through email... kinda makes spending a couple hundred on a dyno a little ridiculous.

I ran Scotts T3s60 MSQ on my little T25 for 4 months with zero issues. My 8 pulls on the dyno netted me 5whp on low boost and 8whp on high boost. The only thing I didn't have was a decent spark table... but now that I've got one of those, who needs a damn dyno except for bragging rights if you've got a wideband?

I wish there was some good documentation on tuning spark with EGT. Kind of like a correlation, like for example "x deg. F EGT off peak + y AFR showed a z% deviation from MBT" would be ideal but I suppose that's not possible to do.

Do a search on 'knocksense'

You can't just tune spark to the pre-knock limit, though. As Matt said, it's nigh impossible to do a good spark tune without a dyno.