MAP Readings on the TMAP sensor - What is it for?

[mnetwork]

I have been trying to find out what the MAP readings coming from the TMAP sensor (combined IAT/MAP sensor on the back of the blower) are used for on a Terminator and haven't been able to find anything on this. I also believe the MAP sensor is only a 2-bar sensor, so it maxes out for higher boost setups.

 

[CobraSam]

What do you mean used for? As far as tuning? Or what the ecu uses it for? It’s a tmap sensor, what else is there to explain? It reads manifold pressure.
(Not being a wise ass at all, maybe I’m not understanding your question and I apologize).

 

[mnetwork]

What do you mean used for? As far as tuning? Or what the ecu uses it for? It’s a tmap sensor, what else is there to explain? It reads manifold pressure.
(Not being a wise ass at all, maybe I’m not understanding your question and I apologize).

Yes, I know what it reads, I am asking what the ECU is using it for. I'll revise my question... how exactly is the ECU using this reading and what decisions are influenced by its reading? We already have a MAF sensor that is used for fuel calculation and we have the integrated IAT sensor on this sensor that is used for the IAT2 (post-charger) air temp readings. How is the MAP reading used by the ECU?

 

[CobraSam]

I gotcha man. Again, my response was not meant to be sarcastic at all, just didn’t understand.
The MAP sends the ECU vacuum and positive pressure readings to help it calibrate what’s needed for fuel. It’s for correct fuel mapping.
The MAF measures flow rate and volume of air going into the engine, but it’s the MAP that tells the ECU about vacuum or boost reference.

 

[mnetwork]

I gotcha man. Again, my response was not meant to be sarcastic at all, just didn’t understand.
The MAP sends the ECU vacuum and positive pressure readings to help it calibrate what’s needed for fuel. It’s for correct fuel mapping.
The MAF measures flow rate and volume of air going into the engine, but it’s the MAP that tells the ECU about vacuum or boost reference.

The MAF is what measures airflow (in our cars) and is what is used for fuel delivery calculation. There is no reason the MAP would also need to be used. MAP sensor are used for fuel delivery calculation in speed density systems not in airflow-based systems. This is why there must be another use for the MAP sensor. Someone with tuning knowledge on this platform would know what it is used for. I have a hunch that this is used when the car is bleeding boost using the boost bypass, but I am not sure.

 

[CobraSam]

Ok, gotcha. I tune my own cars, but only with the Holley system. But, how does the ecu compensate for boost? Does it not reference the map for that?

 

[CobraSam]

Or does it strictly rely on air flow alone?

 

[mnetwork]

Or does it strictly rely on air flow alone?

You don't "need" to know boost you need to know how much air is entering the engine and that is what the MAF is providing. Some aftermarket ECMs and piggybacks add a boost reference for various reasons, but when you have a MAF that is really all that is needed.

I'm guessing the MAP is either used for monitoring EGR operation or as part of the boost bypass, but would love for someone to confirm.

 

[CobraSam]

Well thank you for the clarification. And I feel kinda like a douche as I passed on misinformation. I was thinking of my Holley tuning.
Now I’m curious as well and will have to do some digging myself.

 

[CobraSam]

On the Holley tuning, it all runs on vacuum or boost vs rpm and commanded a/f ratio as I’m sure you’re familiar with. It’s a wicked simple system and I like it a lot.

 

[hotcobra03]

I have been trying to find out what the MAP readings coming from the TMAP sensor (combined IAT/MAP sensor on the back of the blower) are used for on a Terminator and haven't been able to find anything on this. I also believe the MAP sensor is only a 2-bar sensor, so it maxes out for higher boost setups.

Best I can see is it turns on Intercooler pump when temp is reaches
And from reading on site it must send a signal to pcm to pull timing when temperatures are to high

 

[mnetwork]

Best I can see is it turns on Intercooler pump when temp is reaches
And from reading on site it must send a signal to pcm to pull timing when temperatures are to high

That is the IAT side of the sensor. It is a TMAP (Temperature + Manifold Pressure). I'm looking for what the MAP side of the sensor is utilized for.

 

[hotcobra03]

For the 4.6L SC Mustang, the PCM uses manifold absolute pressure information from the MAP portion of the TMAP sensor along with other sensor inputs to determine the proper amount of fuel needed for combustion under varying engine load conditions. The thermistor portion of the TMAP sensor is used as a second IAT sensor. This second IAT sensor, located after the supercharger, provides manifold air temperature information to the PCM.

 

[CobraSam]

For the 4.6L SC Mustang, the PCM uses manifold absolute pressure information from the MAP portion of the TMAP sensor along with other sensor inputs to determine the proper amount of fuel needed for combustion under varying engine load conditions. The thermistor portion of the TMAP sensor is used as a second IAT sensor. This second IAT sensor, located after the supercharger, provides manifold air temperature information to the PCM.

OP-Well, same info I said. I thought so. Let me know when you verify this info. Hope it helps you.

 

[mnetwork]

OP-Well, same info I said. I thought so. Let me know when you verify this info. Hope it helps you.

I'm looking into that quote. Pretty uncommon to use a MAP sensor along with MAF. At least this seems to have to some factual basis to look into. I'll update the thread with info after I get it, going to reach out to my tuner.

 

[CobraSam]

You ever find anything out on this? A friend in the Holley community, who helped write the Holley EFI software, verified the info I told you. For what it’s worth.
Curious if you found out anything different.

 

[ZOSO]

The way I understand it is the factory ECU uses MAF as primary and MAP as secondary. If the MAF fails the car relies on the MAP for proper fueling. Same as if the MAF pegs. The system will go into speed density/fail safe mode.

If you are overly curious unplug it and see what happens. That will tell you right there.