Trying to set-up 3.5 bar map sensor in AEM

All I've just posted this on the AEM forum but figured I'd fire it in here just to see if any of our bright sparks have any ideas. Any opinions well appreciated!

Hello all,

I've spent all day trying to change from the stock j-spec MAP sensor to the AEM 3.5 bar sensor.

The sensor I have is part no. 35-2112.

I'm running the wizard for the 3.5 bar sensor and then rescaling the load break-points back to what they were for the stock sensor.

For good measure I've also copied the main fuel and ignition maps from the stock calibration and pasted those back onto the new one.

When I key on, I've checked the voltage of the sensor, which was about 1.6 volts, which gave a reading of about 100kpa (about atmospheric) and was approximately the same as the stock sensor.

However when I start the engine I'm getting vary strange results. The idle seems to bounce up and down within a 100 rpm or so (before it would stay within 50) and the O2 maxes out at nearly 20:1, where as before it would idle at about 15/16:1 quite nicely.

I'm starting to run out of ideas.

I'll attach both the maps and a log of about a minutes running under both conditions. If anyone has any ideas then please let me know!

normalidle.zip

And here's the 3.5bar map sensor map and log

3-5barmapidle.zip

not the aem map sensor

but is this any use

its for the GM 3bar map sensor

For GM Map sensor, go to options -> full list -> MAP kPa C =0, MAP Kpa m=300, MAP max = 4.98V, MAP min = .35V

To change boost settings on Y-Axis, go to Configure -> Units -> Setup -> Choose Load -> choose a map, or add a map that will have a Mult = the max boost you want to see.

you could also ask kevin huntley at envy as i am sure he has the aem 3.5 bar map sensor on his car

worth a try

Cheers Mark but no good I'm afraid

I think the problem is I've either missed something out, (ie not re-scaled something) or the wiring is dodgy.

I'm going to go over it with a fine toothed combe today.

Cheers

Tony

Tony, I'll try and have a look at the maps tonight (no AEM software on this machine) but it sounds a bit odd. Do the two sensors read the same load when the engine is idling, or has it moved to a different load site?

Where are the "crosshairs" sitting that tell you how close to the center of the loadsite you are? I had similar problems on my cal when I rescaled the load axis and the idle was sitting on the border of two cells and bouncing between them.

What happens if you try and drive the car? Is this an idle only problem or does the car run badly when you try and drive it as well?

Cheers Adam.

It would tend to run in the or around the same load site when it was idling. I couldn't tell you where the cross hairs were. I thought it was suppossed to interpolate between the sites anyway?

I didn't really run the car around whilst like this but gave it a couple of throttle blips and managed to just about nudge into positive boost I think.

I'm starting to think I've got the wrong sensor, as the AEM 3.5 bar sensor should be 30-2112 and I've got 35-2112.

It will interpolate between sites but it seems to get confused at idle pretty easily, probably because the pulsewidths are so tiny. If the MAP sensor is not what it's supposed to be then that would definitely explain the problem! Have they given you a 5 bar sensor instead?

Adam,

I think the sensor I have is definitely not the 3.5 bar AEM one. I've decided to try and calibrate it myself. At atmospheric pressure I'm getting 1.74 v and at 250 kpa I'm getting 4.5 Volts. From this I can create a straight line graph and then use that to caibrate the sensor yeah?

Yet another day spent trying to get this to work...

Aha- I think I've solved it. Kinda. I've just phoned AEM all the way in america and spoke to a chap called Mitch. He seemed very much on the ball. The 30-2112 is the kit number where-as the 35-2112 is the actual part number for the sensor. So I have got the 3.5 bar sensor.

What Mitch said was that, seeing as the stock sensor hasn't got a AEM calibration he couldn't say whether it was right or not to start with. I guess there's two things I can do from here. Re-set the fuel and ignition maps so that they are correct to the right pressures or alternatively just add the difference to the calibration of the 3.5 bar one. Does that make sense?

All,

I managed to solve this. Basically the stock MAP sensor calibration was wrong (Basically out by 0.1 volts worth of pressure). So when I converted to the 3.5 Bar sensor all of the maps were too high by 0.1 volts worth. (About 1.2 psi or so)

I basically used the MAP sensor wizard to set up the 3.5 bar sensor and then reduced the max and min voltages by 0.1 volt and everything sorted itself out.

The one flaw with this is that the at key off, when I read the pressure now it reads 1.2 psi above atmospheric, because I've moved the load site up, when ideally I want to move all my fuel and ignition maps down by 1.2 psi.

With regards to the part number issue, 30-2112 is the "kit" number from AEM (sensor and lead) whereas 35-2112 is the number of the sensor itself.

Thanks to all that helped me solve this.