articfriends

I forgot about this thread, posted real quick while waiting to leave to go snowmobiling. It sounds like what the OP wants to do will be pretty straight forward. Last year Onesickpantera had his motor freshened, a little bit of porting, he installed 02 bungs in his exhaust. His hp 500 tune was close but not quite perfect, he drove around and wrote down his afr's and vacuum readings at various rpm's, texted me and emailed me the info-ie- 4400 rpm's-3 "vacuum/14.2 afr. I took all his readings and converted the vacuum to MAP (vacuum x 3.333), graphed out where his afr's were and needed to be,lets say he wanted to be at 13.0 and was at 14.2, I then divided 13 by 14.2 and got 91.5%, 3" vacuum= 9.99 , 100 map minus 9.99 puts you right at 90 map table,lets say his pw was 5 ms at 4400 in 90 map box, I then took 5ms x .915=4.575, I would round it UP slightly to account for deadband to lets say 4.6 ms. We straightened out his rich idle, a stumble he had off idle, a fuel tuning booboo in his tables down low that had been that way for ever. During initial testing boat went lean from 3800 up progressively worse which validated that his porting actually did something. When he started I copied down a un-molested version of his tune and then modified a COPY , loaded it on a spare mefi3 I had laying around and sent them back and forth making slight tuning changes. In the end his boat ran clean, rpm's higher and had good looking afr's all the way up and down the rpm range. I think it was FASTER and EASIER for me to do the tuning sitting at my desk at home then if I had been on his boat because the stress of bouncing around trying to make changes/calulations was removed from the equation and Scott simply drove his boat and jotted down a few quick notes and AVOIDED sustained running in the 4000 rpm up range at first because it was pretty lean, I think we swapped ecus back and forth 3 times plus the first time of him initially sending it to me to raise the rev limiter and copy it. When I tune my boat again I plan on taking some readings then going and parking while I make changes like I did for Scotts. Something else I did while dynoing the Pontiac that I mentioned earlier is I would modify/write several tunes ahead of time while sitting around at night to try on the dyno the next day so the MONEY clock wasn't running as much while I decided what to change next, instead I could keep uploading tunes until I reached the point where I needed to do specific modifications to tunes that I had tried. Tuning can be fun if you can take the stress out of it, and like I mentioned before, if I already owned something with MEFI I wouldn't go out of my way to change it at great exspense just to have autotune, I would just buy mefiburn and tune it IF you are mechanically saavy. On the other hand, I would NOT go buy another mefi harness and ecu and build sonething around it especially of you are going to be tuning something that is a MILE from a existing tune, Smitty

Unlimited jd

On my duramax I set the ECM up with what efi live calls "dsp5" and I would right 5 tunes each slightly different when I was doing the initial tuning. That way I had 5 different tunes ready to go on the fly with notes of what was different in each one.

Trash

Smitty, if he was lean at 14.2 and wanted to target 13.0 then you wouldn't decrease the BPW from your example of 5ms to 4.6ms, but rather increase the bpw? I believe you made a simple clerical mistake in your post but wanted to make sure I'm not out to lunch.

I think you would add about 9% to the bpw in your example (5.45ms) to target 13.0.

articfriends

Your exactly right, was tired when I wrote that and thinking backwards!!

Trash

No worries, I've made those types of mistakes too often.....I was scratching my head doing the math thinking what trick has this Smitty come up with here!?

JasonSmith

http://mefituning.com/contact
Ben probably has a tune for you.

4bus

Is that for me? I don't want a canned tune

Didn't you tune your own boat with the help from Bob at mefiburn? Anything you want to share? Did you have a thread going?

I'm gonna order the software later today, should be able to start tuning soon

JasonSmith

Yes, for you. Call Ben. He can help. Bob knows Ben because we were one of the 1st to use Bob's stuff so there is some knowledge there.

onesickpantera

4bus, as Smitty said he helped me with mine last year. You're doing something similar by starting with a "close' stock tune so I think you'll be okay. If you were starting from scratch that would be a different story.

4bus

Thank you for the words of encouragement! The software will be here Friday. Looking forward to getting started