Running a piggyback with the flash ECU

[JasonY]

http://www.lingenfelter.com/sites/li...05-2006MAF.pdf

Jason

[HellBringer]

Someone asked me about running a Ford or GM MAF directly into the ECU with no "translator" box. I do believe this is possible.

Have you ever used DSMLink? Or more specifically tuned a car with DSMLink running a GM MAF? When set up for MAF, the majority of the real "tuning" is done via the MAF Compensation settings, which is essentially the translator between what the GM MAF is seeing and what you're telling the ECU. Once you've properly/accurately set up the MAF Comp then you can move to the more granular tuning via Direct Access changes. The point being, though, that the MAF Comp settings are absolutely critical to the overall ability to accurately tune. In other words, the MAF Comp settings are, for all intents and purposes, THE foundation of the tune. That said, the key challenge is the MAF Comp settings will change wildly depending on multiple variables -- location and position of MAF sensor, injector deadtime, BOV placement, airflow turbulence through the couplers and piping, etc...

Case in point -- I changed out a few couplers to try and clean up the engine bay and IC pipe routing, etc.. and rotated the MAF 45° in the process. As a result, I ended up having to make some fairly substantial changes to the MAF Comp settings to bring fueling back in line. Something as simple as physically rotating the sensor had a tangible impact in the way that it read airflow. Further, when I converted to E85 I went from 1000cc injectors to 1750cc injectors with a significantly different Deadtime. When I 'rebuilt' the MAF Comp to suit it ended up looking wildly different from the old settings across the board; in other words, simply scaling the settings to account for the different injectors would have put me nowhere near where it needed to be.

My overall point being, based on my experience with GM MAF tuning via DSMLink, I don't believe there is a way to code a fixed translation that will be plug n play -- there are an infinite number of variables that require each individual setup to be configured by the user/tuner, and these configs will changes each time a setup change is made. I don't believe it will be as simple as determining the airflow/voltage scaling because what you identify on a flow bench will be drastically different in practice. DSMLink provides base templates depending on which GM MAF you're using, but the templates are just that, and in my case were not even really applicable -- my settings ended up nowhere near the template.

[donniekak]

Maf comp should never be used to correct for injectors, after the maf is calibrated. Handle dead time, and scaling in the dead time, and injector scaling.

The gm maf does have wildly different properties depending on where it is in the piping, and the orientation of the maf.

[HellBringer]

^^Yeah, I didn't mean to imply MAF Comp was used to 're-tune' the new injectors -- that was done via the Global Fuel and Deadtime. However, once I had the new injectors dialed in (for E85), I had to make significant adjustments to the MAF Comp settings. My gas/1000cc settings were much different than where my E85/1750cc settings landed. In either case the car started and drove like stock, A/F was solid and BoostEst was fairly close. The guy I sold the car to has been beating on it on high boost (as much as the internally gated 61mm will make) for weeks now, and it still runs like a champ!

[Greg E]

Maf comp should never be used to correct for injectors, after the maf is calibrated. Handle dead time, and scaling in the dead time, and injector scaling.

The gm maf does have wildly different properties depending on where it is in the piping, and the orientation of the maf.

I'm trying to get people away from tuning via injector correction. The problem with it is you're tuning the entire map with that correction as opposed to tuning for the VE changes (MAF comp which you and Abram are referring to). The object of the game is to get your IPW to match your desired AFR. Wether you tune via the fuel map and injector scaling or just MAF comp... Either will give you the same result but if you flow rate your injectors, they flow that injector scaling number. You are literally lying to the ECU about the injector flow rate to get it to match your desired AFR.

Same issue here with knowing the MAF scaling. Since we don't have live tunability, you'll get a better base tune with knowing that particular scaling.

All cars will need a custom tune MAF comp (VE) map for all the reasons you guys are saying. It's much much easier to tune that when you have your base scalings set up correctly. Especially since we don't have live tunability with these ECUs (yet).

In my "How to tune a 3/S" manual I go over setting your injectors and MAF scaling first, then using the fuel table more as a target AFR map (as I feel it should be) and adjusting MAF comp to reach that desired target AFR. Much much easier to tune that way as opposed to the way some of the evo guys do it.

Both ways get the same results but from experience, this way is easier.

[Greg E]

Btw a sad ugly truth is most of the 3/s community just want their cars to run/drive. Most don't want to spend the time/$$ getting it tuned perfectly. If it has the 'potential' to make power, thats good enough. Most guys just want the base tune and let the fuel trims fine tune to make it drive. I can give better base tunes if I know the sensor and injector scalings.

Never made much sense to me why guys spend so much $$ on mods but never try to get the most power out of that fortune they just spent.

[donniekak]

The best way to calibrate the maf is to make sure the injector settings are correct, then set the target afrs flat under boost, and tune the maf comp table to match the target afrs. Also, the closed loop trims are used to get the correct maf comp for low flow.

Many people count on the maf being properly calibrated to measure changes in airflow with different setups. It provides a great way to compare when everything is in accurate lbs/min.

I've been tuning stock ecus with custom hex code on dsm's for years, so I don't use dsmlink, but there are several tuning tools in their software that are great. I just dont know if the work required to do this for the 3s ecus would be worth it, as link has sold thousands of units at $500+ each. I don't know if the 3s market is that large. Either way, it's great that people have taken an interest, and created a much better solution than safc's.

[Greg E]

The best way to calibrate the maf is to make sure the injector settings are correct, then set the target afrs flat under boost, and tune the maf comp table to match the target afrs. Also, the closed loop trims are used to get the correct maf comp for low flow.

Many people count on the maf being properly calibrated to measure changes in airflow with different setups. It provides a great way to compare when everything is in accurate lbs/min.

Didn't I just say that?

I've been tuning stock ecus with custom hex code on dsm's for years, so I don't use dsmlink, but there are several tuning tools in their software that are great. I just dont know if the work required to do this for the 3s ecus would be worth it, as link has sold thousands of units at $500+ each. I don't know if the 3s market is that large. Either way, it's great that people have taken an interest, and created a much better solution than safc's.

Look Jeff! Another pessimist!

Sorry. Inside joke. I need to collect $$ everytime someone tells me this. I also need to collect $$ every time someone clams to be the first person to flash tune one of these ECUs.

I'm sure eventually ill figure out how to do it. No way any sane person would do this for $$.

[Toni]

Greg, have you dynoed any other cars with similar mods to mine? (15gs, 550ccs,20psi). I am curious on the load numbers they are reaching.

[Greg E]

Those running a Mitsu MAF seem to get load numbers more in the 240-260 range at your power level. I have yet to see anything greater than 275 load. Still well with in the 1 byte limitation in the ECU. I imagine well over 650 HP before needing to come up with some creative work around for that.