scratch tune SD with no maf logs
 

What kind of pointers can some of you toss out there to help someone that does not have a MAF to get started on a SD tune?




Ive tuned mine from scratch several times and also a buddy's. But I cant help but doubt whether Im doing it right. It has always been said to make SD loads match MAF loads and really not a whole lot of talk about what to do without MAF loads.


Ive always ran 1:1 in my kpa-load table


The 1st time I did it, I just made the fuel map and WB match as close as possible by adjusting RPM VE and maf compensation, basically just making both maps have a "normal" topo.


2nd time was to make logged kpa and logged load match up by adjusting rpm VE, then adjusting maf compensation to correct fueling.


Both methods resulted in a fairly decent driver.


Now Im making some exhaust/turbo changes, removing my IAT sensor (going to fuel temp) and adding injectors. My plan was to install everything except the injectors, get VE dialed in, then install injectors and dial them in. But this is all assuming that my 2nd method above really is the way to do it.


If its not broken, don't fix it? Or is it broken?

I think its up to you how you want to do it. I don't think there is any wrong or right way.

One thing though, for method two, you say you adjust rpm ve until kpa and load match up. Neglecting any other compensations that may be in effect, if you set your map ve table so the axis and the values are equal and then set rpm ve to 100% at all rpms, kpa will equal load. This is what jcsbanks coined as easy speed density.

{thumbup} I've found there to be a few different techniques people are using for starting without a MAF.

Some of my first tunes were setup utilizing the way you described in your first post, ie. Map to Load 1:1 and adjusting RPM VE table to match the AFR Map. While I don't think this is a "bad" way of doing it, I don't believe it's really correct. I was using 120% VE at some RPMs just to match my table, which made part throttle pulls a bit awkward.

What I did was set my Map(KPA) to Load at a 1:1 ratio to start, setup my RPM VE table like so;

http://jeffbeagley.com/random/rpm%20ve.PNG

then used MAF Compensation to adjust airflow/fueling to match my AFR's in the map like so;

http://jeffbeagley.com/random/maf%20compensation.PNG

I then adjusted my MAP(KPA) to Load table to match my desired boost levels.. ie 20psi=200load, and so on.

http://jeffbeagley.com/random/ve%20calibration.PNG

If this is the correct way to do things is beyond me, but I will say this is the best setup I've ran and by far the smoothest. Hope this helps! :beer::beer:{thumbup}

So youre saying that putting 100s across the board in both KPA-Load and RPM VE mathematically makes it so that kpa will equal load. That make perfect sense, just really hasn't clicked that way in my head until now.







What led you to arbitrarily do this? Just knowing the efficiency of the turbo/engine?




For me it makes the most sense to leave as many variables out of it. Im wondering how odd my maf compensation table would look if RPM VE and kpa-load are set at 100.


Ive read the easy speed density thread a while back but for whatever reason never really took to it. Im currently on 3D SD and now Im considering changing back to 2D and trying the easy SD route.

You are correct in your load math.. Load % ( In KPA to Load table ) * RPM VE = load.

I used those values coming from the 9417 3D SD Rom ( I switched to the 9653 2D Rom due to a lot of cold start issues ). From what I understand the RPM VE table just uses the term "VE" while it has nothing to do with VE.. and they did that to teach proper tuning etiquette.. Please correct me if I'm wrong in this understanding.. So standing behind that Idea I know the VE table should never truly be over 100%.. while I did go over it a hair doesn't really matter :p

I would be interested to see what the Maf Compensation would look like having it all 1:1 / 100%

Just to be clear, you don't put 100s in the KPA-load, you just make the left side equal to the right side, like the table Jeff posted above.

When john banks first came out with the sd roms, a lot of emphasis was placed on adjusting the tables so that your loads pre sd matched up to your loads after sd. In doing so you could keep your existing fuel tables ad such. I wasted a lot of time doing this. I now find it easier just to adjust the VE tables and MAF compensation so afr map is close to actual afr and then retune the timing table.

{thumbup}:beer::beer:

on the same page here, I just worded it incorrectly.

thanks guys.

I know this is a long shot, but do you still have these pictures in this post?

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