I just ordered one. I currently have a GM 3bar. My question is...obviously I need to solder the new harness on, but will that car run with the AEM sensor without modifying the tune? I run Neptune and the car was tuned on the 3bar.

 

you will need to change the setting in the ecu becasue the voltage specs are goin to be different for the 2 map sensors

 

I was afraid of that. That is the ONLY thing that I don't like about the original neptune. You can't make any changes being the end user.

 

With a new map sensor, you NEED to retune the car. Its not really a button click, burn a new map, and your done type of thing.

 

kinda why I chose the new hondata s300. it is a button click with it and end users can access it and at least montior the system.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by oscarmayer &raquo;</TD></TR><TR><TD CLASS="quote">kinda why I chose the new hondata s300. it is a button click with it and end users can access it and at least montior the system.</TD></TR></TABLE>

Um, you still need to retune the whole car. End of discussion. Anyone that has tuned a car ever will know that when you swap map sensors you will need to retune. The retune may take a short period of time, but a retune is necessary regardless.

 

inteesting I did not know this.

Can do you explain why this woudl have to be done? I'm asking because to me, (i'm not a tuner) jsut changing the senor and setting the ecu to use it's readins as the map should really not effect the tune. But again I'm not a tuner so this is interesting info for me. please if you can explain why it needs to be done in as much detail as possbiel. (This grasshoppa is listening)

 

Because no sensor is perfectly to spec. You plug in the factory data sheet equation and convert, but it will never be perfect. The position of the map sensor, its vaccum source, the wire used, and other things are all variables that simply cannot be accounted for. Your fuel maps are based mainly on rpm and voltage from the map sensor. If you change either one of those devices, you can expect to need a retune. Another thing about map sensors is you are limited to 5V. The more pressure in that 5V, the less resolution. As the resolution changes the ability for your current tune to correspond to the new map sensor may become off and again, require a retune. Overall, expect to retune, and if things run well concider yourself lucky.

 

Because the load cells will be completely different. This is because the voltage at standard atmospheric pressure is different... which changes the map sensors scalar's and offset values.

So for example, with a motec 3 bar you will be at 3047mbar at 5 volts when with a 5 bar you are at 5625 mbar at 5 volts. So if you originally were tuned with a 3 bar then switch to a 5 bar your ecu will read in a completely different load cell than it actually is in.

So instead of reading at say 200 millibar the ecu will think it is at 800 millibar... these are purely fictional numbers.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by PrecisionH23a &raquo;</TD></TR><TR><TD CLASS="quote">Because the load cells will be completely different. This is because the voltage at standard atmospheric pressure is different... which changes the map sensors scalar's and offset values.

So for example, with a motec 3 bar you will be at 3047mbar at 5 volts when with a 5 bar you are at 5625 mbar at 5 volts. So if you originally were tuned with a 3 bar then switch to a 5 bar your ecu will read in a completely different load cell than it actually is in.

So instead of reading at say 200 millibar the ecu will think it is at 800 millibar... these are purely fictional numbers.</TD></TR></TABLE>

Thats not really a problem as if the header says 10psi, sure it will be a different output voltage but the ECU already has calibrated that. So basically if you change the map headers to be very similiar to what you had previously, your time retuning should be minimalized. That doesn't take away from the fact that your voltage scale is limited to 0-5V and the ECU takes that 0-5V and converts it into numbers from 0-255 which means resolution can be iffy thus the need for a retune.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nowtype &raquo;</TD></TR><TR><TD CLASS="quote">

Um, you still need to retune the whole car. End of discussion. Anyone that has tuned a car ever will know that when you swap map sensors you will need to retune. The retune may take a short period of time, but a retune is necessary regardless.</TD></TR></TABLE>

No ****, that's a given. I re-tune with with the winter/summer climate changes.

 

i knew about climate(sp?) changes but not about sensor changes.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by maxspeedhonda &raquo;</TD></TR><TR><TD CLASS="quote">No ****, that's a given. I re-tune with with the winter/summer climate changes.</TD></TR></TABLE>

See, you shouldn't need to retune then. The whole point of having an IAT sensor is so you can run one tune all the time.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nowtype &raquo;</TD></TR><TR><TD CLASS="quote">

See, you shouldn't need to retune then. The whole point of having an IAT sensor is so you can run one tune all the time.</TD></TR></TABLE>

Yes, but I am very **** about it. It costs **** to have a tune updated.