Thread: Prepping for MAP conversion

Couple questions..

#1 for IAT sesnor use pin #8 and pin #21 or #29? Can i just cut the plug off in the bay an wire it to the iat sensor an be good to go? if so does anyone have a pic of what it looks like, or maybe describe it and its location?

#2 when setting up my map sensor, i'm only seeing negative numbers in the gauges and datalogs, an even then nothing lower then -17 (meaning its usually 18-22) even then i had to mess with the multiplier, added .4 to get it to match my gauge which shows 22.. and yes i set it to inhg/psi.. did i wire it up wrong? i followed the write up as far as i could tell..

Ah no, i had all similar issues and still havent totally worked them out. Im using a Australian Spec Sentra ecu, 68c00, which doesnt seem to have EGR temp input for the IAT sensor to connect to. I ended up going with ADC inputs for both Map and IAC, even tho i had gm IAC sensor i had to calibrate it manually, and ended up with 2 5k resistors in parallel to get it a bit closer before calibrating with water of various temperatures. Think i got it close but not sure yet.

I dont understand the scaling for Map sensor yet, using Omni 3 bar didnt work at all and gave me load about 3/4 up the map. I need to do more work on this when i get time. Did notice on logs that the output of the Map sensor is really similar to Maf on graph log, but is a lot higher numbers, but the shape of the line is pretty much identical. I just need to work out how to translate this to a load to control a load map.

Im hoping what ive been working on can help others to get similar setups working faster too.

Have you got your Map wired into Maf wiring or adc input? If maf wiring is better and doesnt need as much calibrating, then i might go with that, but its nice to be able to use maf still atm.

Would a step by step guide be asking too much?

The guides for wiring them are here.

NismoTronicSA Resources

As far as the MAP sensor scaling is concerned .. the drop down selections are the "default" scalar/offset for the MAP sensor from factory specs.

I have found that almost every MAP sensor I have hooked up, either through the ADC input or the MAF input will need additional corrections to the scaling.

To do this, choose the MAP sensor you are using in the drop down THEN choose custom. When you choose custom, it will allow you to edit the scalar and offset values so you can get your load scales to match properly.

Here are a few that I have done for customers that have been pretty much spot on for their setups.

OMNI 4bar
OFFSET: 0
SCALAR: 800

OMNI 3bar
OFFSET: 5
SCALAR: 700

OMNI 2.5bar
OFFSET: 100
SCALAR: 500

As far as the IAT sensor installation is concerned, there are only a few ECUs that actually use the EGR temp input for the FWD SR20DE ECU.

So, I would suggest following the instructions on how to wire up the IAT through the ADC input box.

I think I catch your drift... thanks man I'll report back tomorrow

Would it be silly to cut the egr wiring by the ecu plug to make use of the wires since theu are almost in the perfect spot and already ran?

another thing, in this link

http://www.nismotronic.com/Resources/MapInstall.pdf

it says,

RED * switched 12v
BLK * ECU GROUND
PNK * 5v output to MAP SENSOR 5v SOURCE
YLW * 5v INPUT from MAP SENSOR SIGNAL

but it doesn't mention the green wire in the picture, which is going to the outward ground for the map sensor.. i grounded my map sensor to the strut tower, i used a tester around the bay and it seemed as good place as any..

should i change this? should i ground the breakout to the same location as the ecu grounds and then ground the map sensor to the breakout? or will it be ok as is?

Also when wiring the IAT using the breakout box is it ok to share the 5v out with the map sensor? and does the 5k resistor go between the sensor and ADC or do they kinda run together before the sensor? and again, should i use the breakout box ground or does it matter?

i do know that having things share common grounds can sometimes help, but if its not a big deal i like to make things simple.

I put the resistor straight inside the ADC box between the 5v and ADC terminal, but then ended up putting another 5k resistor in parallel to get the reading a bit closer as the calibration was way off.

The adc box has 3 terminals marked as ground. As i see it, the green wire is the map sensor earth, as a signal earth, and the black wire is to ground (chassis) to provide the 5v output.

The 5v is regulated, so shouldnt matter if i has more than one load on it. Ive got a couple of different grounds/earths running around as my wideband is wired into some of that part of the wiring as well, i have a earth from the wideband to the sensor earth on the adc so no chance of voltage difference, and my wideband reads exact without any offset required.

Only you can answer that question, but I use the stock harness as much as possible. Just be sure to document your wiring changes for the next guy.

Dave

The IAT conversion table was made with my GM open-element IAT sensor on my EGR temp. sensor input using my thermocouple, plugged into my tire temp. gauge, for calibration. Everyone must calibrate their IAT conversion table to their own satisfaction.

Dave