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Old 08-17-2016, 10:25 AM   #1
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Default AEM ems MAP/IAT and NB idle

93 chassis with rebuild MSM engine
AEM 1710 ems
94-95 basemap with settings changed to support below changes
AEM WB O2
AEM 3bar map
GM AIT
Sequential injection
Stock purple injectors
NB TPS
NB IAT
NB Cam and Crank sensor
NB 4 tooth crank wheel
NB2 VVT coils

I've managed to get my car to run and idle but the car will not take throttle. I'm assuming its because my fuel map is messed up due to swapping to a MAP/IAT.

Also Ive had to unplug the IAC valve to get the car to idle otherwise it will just hunt and go all over the place.

Does any one have the NB IACV settings for an AEM ecu and a MAP/IAT fuel map for a 1.8 that I can just try out?

Thanks

Last edited by Neilv; 08-19-2016 at 12:55 PM.
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Old 08-24-2016, 10:47 PM   #2
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Nobody has swapped over to a map/iat on a 1.8 or is using an nb iac motor with an aem ecu?
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Old 08-27-2016, 05:51 PM   #3
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There is an AEM subforum where people using those possibly hang out, but it doesn't seem overly commonly used. That said, whatever settings there are should match pretty well with megasquirt (or almost any other ECU), as well as "common tuning practice". If it starts and idles I guess the basemap isn't that far off, and with a wideband o2 adjusting it to run decently shouldn't be that difficult.
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Old 08-27-2016, 07:34 PM   #4
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The timing maps between aem and megasquirt can be swapped over but the fuel maps use different units that i havent been able to convert.

I know people are are using these sensors and parts and are running them. I just havent gotten a response back from any PMs or posts.

Unfortunately im doing this with a freshly built forged motor so im not looking to **** it up. Im also breaking it in n/a before going boost so it would suck to pay to get it tuned then retuned all over again
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Old 08-28-2016, 04:50 AM   #5
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Just googling around for screenshots suggests that AEM uses injector pulse width in the fuel map table (in milliseconds), presumably before it's corrected for injector dead time and other factors. Essentially, the relation between pulse width and volumetric efficiency (which is what the MS fuel map uses, usually in %) is something like this:

PW= (VE * map_load * displacement_per_cylinder) / (target_afr * injector_flow)

(apply unit conversion factors to taste)

Apart from the target AFR which will vary a bit in various parts of the table, it's essentially a constant scaling factor between VE and load to pulse width, so based on whatever load cells seem to work fine (engine runs well and you see reasonable AFR) you should be able to set up the rest of the table based on a MS base tune and whatever the scaling factor turns out to be.
Also it seems AEM tuner software likes to show the MAP load (Y axis) as PSI gauge pressure while MS/Tunerstudio has kPa absolute pressure. There be dragons.

Having it reasonably tuned for NA before going boosted is a Good Idea. If you have some clue what you're doing tuning it, there should be no real need for a paid tune unless you're concerned about maximising power or fuel economy while you're NA.
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Old 08-29-2016, 10:55 AM   #6
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With the AEM fuel tables I can use 3 different units: duty cycle (0 to 128), pulse width (0 to 19.1) and raw (0 to 255). I can also set the X and Y to the same units as the MS ones too.

I never thought of that. I could just use the idle squares that have the AFR i'm looking for and just use my own conversion factor to get the rest of the table but comparing to very similar MS maps since there is a billion out there. I mean it may not be exact but i'm sure it would run and could fine tune from there. Only difference is AEM is 16x16 vs 12x12 so ill have to do some interpolation.

Just have to figure it I want to use the stock 265cc injectors or the 660s I planned to put in later.

Thanks!
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