Running a piggyback with the flash ECU

[Greg E]

Seems this topic comes up a lot. Yes you can do this. In fact, I recommend it for 2 reasons: Both the ARC and the MAFT give the advantage of an aftermarket free flowing MAF AND you can keep the live tunability and simplicity that you otherwise lose via tuning straight with the flash.

You'll actually find your car will drive better just using the flash ECU to set the injector scaling and fine tuning the timing table. Throttle response is smoother, start up is better and best of all, there's no limit to what size injectors you can run.

You literally get the best of both worlds.

[futurevr4man]

good cause its what i will be running very shortly (maft)

[jras312]

Any new info on usin a gm-maf and translator in blow through? The throttle hang issue or whatever you are calling it? Or was that with the maft in general, regardless of maf position?

[Greg E]

Any new info on usin a gm-maf and translator in blow through? The throttle hang issue or whatever you are calling it? Or was that with the maft in general, regardless of maf position?

I haven't seen Toni's car since our last Dyno and he's put the car away for winter storage. GTWizzard had great luck with running the MAFT on his NA with a Chromed Clone so I suspect it's an issues isolated to Toni's car or something with this specific setup.

[Toni]

It would be great news that it's just my car that is hanging the throttle. I just wanted to enjoy the car this year so I didn't screw around trying to fix this issue. While it can be an annoyance it's not at all a hindrance. Kinda fun on the road course actually lol.

Anyway, I plan to dive into this problem in the Spring and figure this out once and for all.

[Roybatty]

Toni, u still using a Maftpro?

Sent from garage

[Toni]

Never used a Maft pro, using a Maft gen II

[Roybatty]

Sorry, was gleaning info from thread on old Site & thought I remember seeing you had some insightful questions.

Sent from garage

[Greg E]

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

The EVO guys tried this some time ago but my search-fu failed to find the discussion thread. From memory, it didn't work well but the problem wasn't hardware. The 98/99 cars have a 5V input or 3 we can use for a hot-wire MAF.

See the problem was no one knew the voltage scaling for the MAFs or in other words what airflow corresponded to what voltage. It was literally guess and check work which everyone just gave up on.

Its actually not very hard at all for me to tweak the code to use a different pin input. Even the tables currently in the code can function the same way only instead of referencing HZ, the scaling needs to be changed to reference voltage. Very very easy.

In fact, I even have a GM 3.75" MAF that was loaned to me by JGroove to do some experimenting. He's never asked for it back.

Maybe I just suck at Google but I've never been able to track down an airflow vs voltage chart for this sensor nor do I have the capabilities for setting up a flow bench to test one. Jeff has tossed out ideas for building one but that's a lot of work for little potential.

Another minor detail is the ECU measures everything in grams per stroke. So really I'd need to know the flow in a similar unit to make it work with the current ROM.

These are all the details with that setup.

[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.