All,

I've just posted this on the aem forum, but was wondering if you guys had any ideas....

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!

Here's the 3.5 bar MAP sensor calibration and log

Cheers

Tony i can't read these files, i'm assuming they are for the AEM software.

Have you monitored the MAP sensor when the car is idling, i'd expect this to drop to about 1v and also for the AEM software to register the drop in voltage\pressure.

Is the supply to the MAP sensor stable at 5v (i think) with the engine running ?

Martin,

I don't think it's the MAP sensor setting themselves that are causing the problem as it seem to give reasonable values, and similar ones to the stock map sensor.

As I said in the previous post I think there's something I'm missing.

If your interested you can download the AEM software for free from their site.

http://forum.aempower.com/bbs/viewtopic.php?t=8610

Try reading the manual that comes with it, it's quite mind-blowing. ?http://www.mkivsupra.co.uk/iB_html/n...ns/shocked.gif

Cheers

this is not correct. the new sensor should have a different voltage at atmospheric.

i cant understand why u have adjusted the break points back to what stock sensor was. (r u doing this to the SENSORS MAP or the fuel ign maps)

nor should u have to readjust the fuel and ign maps after loading the new sensor map.

if i load a new SENSOR map into mine that does not match the sensor i have i get the same symptoms. just load the new MAP sensor map into the unit and dont do anything else, it should work fine.

****IM GONNA HAVE TO ADD A DISCLAIMER HERE COS U R MESSING WITH THE VERY SENSOR THAT CAN TOTALLY BUGGER YR ENGINE VERY EASILY. I DONT HAVE THE CAR IN FRONT OF ME, NOR AM I AN EXPERT AND YR NOT PAYING ME http://www.mkivsupra.co.uk/iB_html/n...cons/smile.gif THIS ADVISE COMES WITH NO GUARANTEES AND ANY DAMAGE IS SOLELY YR RESPONSABILITY, SO THERE.****

http://www.mkivsupra.co.uk/iB_html/n...ticons/wow.gif

Have to admit thats some pretty comprehensive reading material in that manual !

Martin - Tell me about it. It's taken me 9 month's to get to a point where I thought I knew what I was doing. Obviously I was wrong http://www.mkivsupra.co.uk/iB_html/n...icons/down.gif

eyefi,

I meant the pressure's were reading the same not the voltages.

I'm only running the stock tubbies up to 18 psi, so I don't need the full range of the sensor. I want to make sure I can get it to work with my current fuel/ignition maps before I started to add anything to the top of the map.

I thought the idea was to fit the new sensor, then paste your ignition and fuel maps back into the load-sites that they were in to start with. Which is what I've done.

If you run the MAP sensor wizard, the number of load break-points stay the same, but the values in them change, so you definitely need to adjust any tables that has load on any of the axis to suit the new loads

I've also re-checked all the wiring, and re-souldered the joints at the sensor end, but no good.

This is getting frustrating now! http://www.mkivsupra.co.uk/iB_html/n...ticons/cry.gif

ok, so the voltage was different at 1 bar absolute?

it doesnt matter matter that yr not going above 18psi, u will just b using a smaller part of the sensors range eg <4v.

u should b loading a map for he sensor. this map should look something like this:-

1v = 2psi
2v = 5psi
3v = 8psi
etc

this map is defining what voltage the sensor produces at what pressure. this map should not b adjusted at all because the sensor will always produce 3v at 8psi. this map in turn (along with RPM) tells the fuel and ignition maps where in the matrix the car currently is. u should have no need to adjust the fuel or ign maps because the sensor map is making it all work correctly

does this look right with what u have on the aem software. this is how it works in most ecu's, im sure this is how it works in the aem.

what is on the x & y axis of the fuel and ign maps. it should b x=RPM y=pressure kg/cm (not voltage)

Yup that's exactly what it is. Load against RPM.

There are 16 load sites available on the AEM. So if you had a 8 psi MAP sensor you'd probably have load going from -8 psi to +8 psi. As long as the fuel/ignition value entered for a certain load/rpm site stays the same then all should be cushty right?

That's what I thought and the reason why I'm sure I've missed something else! After spending yet another day trying to sort this I'm fairly resigned to giving up.

The only thing I think that maybe wrong is that the AEM 3.5 bar sensor is 30-2112 and my sensor is 35-2112 but there's no real reference to the 35-2112 on the AEM forum (Plus I was told it was 3.5 bar sensor when I bought it) Not sure and am awaiting confirmation one way or the other.

what is the unit of measurement on the load axis?