In theory the hotwire sensor used with the maft should already account for both baro and iat ( debatable).

You can use gutted stock mas for both or use an aem iat sensor if easier but never seen a standalone baro sensor?. Only measure ambient air temp, not charge air temp as the mitsu ecu was never designed to see that..

 

Aup mate.

Ye the maft uses a set iat and baro signals. It's ok but u need a summer tune and a winter tune as the fixed signals change the AFR's.
Think of tricking the maft needs to see iat and baro from ecu so it can "fix them ".
Wondering how to trick the maft so it doesn't throw me a cel.

Forexample .... Wire in resistors to into the baro and iat input. To the maft?

 

Possibly, it might need to see a voltage. Stock sensors run off 5v.

 

It would mess up the tune. The gm maf compensates the frequency signal for baro, and iat, it locks the baro and iat signal to the ecu to prevent a check engine light. If it didn't compensate for pressure, how else could you run it in the upper intercooler pipe. Not to mention the air in that pipe can be anywhere from ambient, to 200+ degrees.

Baro, and iat are needed with the stock maf to calculate mass flow. The ecu uses volume, pressure, and tempature, to calculate mass. The gm maf measures mass directly. The translator locks baro and iat at a set level, and the only variable is volume. It varies the volume signal against set pressure, and tempature to get the ecu to calculate the mass.

 

I see......

But can you not somehow for example.:

Wire in the stock MAF and mount on the firewall and use the IAT and BARO so that the ecu doesnt "fight" with the GM MAF.

The MAFT needs the IAT and Baro wires into the maft unit so that it can lock it down. Could you not trick the maft into thinking its receiving the iat and baro signal.

Just worried about the ambient air temp changing loads and totally throwin the tune out.. Not worried about a .1 or .3 afr change... just read stuff on sometimes it can throw you into the high 12s on WOT ...

 

Ambient air temp is taken in to consideration in the gm maf. Unlocking the baro, and iat would cause the tune to wonder.
Just to be clear. The stock ecu uses volume(Karman hz) baro, and iat to calculate mass air flow. The gm sensor measures the mass directly, no matter what tempature, or pressure the gas is, this is why it works in blow through. The translator adjusts the Karman value against a steady state iat, and baro signal to communicate the correct airflow with the stock ecu. Adding a tempature, and baro signal to the ecu would not compensate for iat, and baro, it would overcompensate.
If the the gm maf couldn't compensate for pressure how else would it work in a intercooler pipe with pressure anywhere from slight vacuum, to upwards of 30psi?

 

Hotwire sensor neither knows nor cares what the pressure is it just measures mass flow as you say, BUT the tune can wander with different ambient conditions as Dave says and he's looking for w way to stop it..

 

Just wired in a gen II MAFT and it set off my 12 and 25 codes (baro and maf) but my data logger is showing signals from both. So curious to see where this thread goes!

 

Just thought if I wire in the stock maf for the air temp /baro only then it wouldn't throw tune out as much as it ecu will be seeing exactly what's outside.

Like mount the stock maf somewhere. I'm thinking if the ecu is seeing true air temperature then it can add/take fuel accordingly.. It's not a massive issue yet but do t wana be tuning the car every time I drive itlol.

 

GM cars typically also have a MAP sensor and IAT sensor which takes an ambient reading when you first turn on the key (before starting) so the PCM can adjust to the current conditions (or altitude even).

Ford does basically the same thing with their hot wire MAF setups, only they dont have a separate MAP or IAT sensor. theirs are typically built into the MAF sensor.

 

The cars that run the sensor used in the maf translator setup do not use a map sensor.

 

Also, a hot wire MAF doesnt directly measure the mass of the air, rather it measures the velocity (as does the stock Karman Vortex sensor, not volume), which when combined with the temp and MAP sensors (or barometer in some cars) the mass can be determined.

 

airflowoptions [ECMTuning - wiki]

 

Even better,
gmiateffect [ECMTuning - wiki]

 

the GM MAF is a cold wire sensor (not a hot wire), which measures the change in inductance based on the air flowing across the sensor. this change in inductance correlates to the mass of the air. so yes, the GM MAF doesnt need a temp or baro reading.

 

Have a good search on here for threads by Mellon with his datalogging which showed a 1 point afr swing between morning and evening with exactly the same tune..

 

I think that was old software chip but still... ^^^^^ what I'm worried about.

Also that might of been a faulty gm maf... Did he replace that aswell Keith?

 

yeah he ran the maft. He had tuning drift that he could never solve and the car ran the same track times with the bypassed bov maf setup so he got rid of the maft.

 

http://www.3si.org/forum/f35/f-changes-outside-temperature-246080/

 

Interesting. The thing is, when its hot it should be running richer. When cold it should be running leaner. Exactly the opposite of what Mellon was experiencing. If you added an AIT sensor in this scenario it would only make the issue worse!

 

Curious if his fuel trims are beyond maxed. That would definitely be a more logical explanation for this behavior.

Edit: found the fuel trim notes later in the thread but unfortunately they are only showing the rear o2 sensor trims. This was before we knew about the dual bank fuel trims.

Either he had a huge boost leak or his front fuel trims were whacked!

 

This is a great question/thread! I have a MAFT1, 3'' MAF (blowthru), and a flash ECU and I'm HIGHLY curious as to know if I'm going to have to neuter my tune or deal with a bad MAF/wandering AFs as much as people say they are having problems. I plan on having the MAFT 0'd out and obviously adjusting from the flash part.