AEM Ultimate Resource Thread>>>>

[Tasker21]

Hey,

I did a couple quick searches and found nothing on this. I have a 96 vr4 and am trying to hook up my aem ems with the map and IAT sensors. Where do the 2 wires for the IAT go. Also I read there is a white and black wire. Mine has 2 black wires. Polarity must not matter? Thanks.

Terry

[mjannusch]

Originally Posted by Tasker21

I did a couple quick searches and found nothing on this. I have a 96 vr4 and am trying to hook up my aem ems with the map and IAT sensors. Where do the 2 wires for the IAT go. Also I read there is a white and black wire. Mine has 2 black wires. Polarity must not matter? Thanks.

Polarity doesn't matter - it is just a thermistor (resistance varies according to temperature). It connects to the ground and temp sensor wires on the factory MAF connector. I don't know offhand what the colors are or pin numbers, but you should be able to figure that out from the service manual.

[UPP]

There are writeups on that with some good pics....I just can't remember where! I think maybe stealth316.com under their tech articles.

Don't quote me on this, but I think it was black was ground, and red w/blue stripe was the signal. And both of them are on the MAF pigtail. Make sure you used the ground on the MAF though, sensor ground is supposed to be "cleaner" than just a regular ground...

UPP

[Tasker21]

Thanks for the info guys. Its nice to know you can always rely on people here when you cant find the answers.

Terry

[TwinTurboKid]

Finally got to installing this today. Soldered all the wires into the harness and there is one wire that you have to put in a terminal because there is no wire there (PIN 53 Map). The AEM came with some terminals, but they don't seem to be the right ones? I can push it in, but it doesn't lock in like normal ones do. Anyone know if there are any other ones? It doesn't seem right.

[Sarge]

Just curious (don't have an AEM.....yet) but since 96 and newer models came with MAP sensors, can we use that? (instead of installing a new MAP sensor with it). Granted, I'd still "need" an IAT and WBO2 sensor, but could the stock MAP sensor be used on the 96 and newer cars just to save a few bucks?....or are they as unreliable as all the other stock sensors?

[cjbyron]

Best thing is a new GM sensor (usually 3.5 bar is what majority of people use but some 5). MAP sensors are cheap. If concerned about the cost of a sensor then the AEM system isn't a good choice.

[mjannusch]

Originally Posted by Sarge

Just curious (don't have an AEM.....yet) but since 96 and newer models came with MAP sensors, can we use that? (instead of installing a new MAP sensor with it). Granted, I'd still "need" an IAT and WBO2 sensor, but could the stock MAP sensor be used on the 96 and newer cars just to save a few bucks?....or are they as unreliable as all the other stock sensors?

No, don't use the stock sensor. It isn't what the AEM needs, on many levels.

[arghx]

Hi everyone,

Longtime lurker with some driveability tuning questions. I come from the Rx-7 world but I have a decent background in tuning and tuning theory. A friend of mine is looking to run an AEM EMS on his VR-4 for an 800-1000awhp twin turbo build (obviously with enormous injectors and aggressive cams), and in my experience building a basic fuel and ignition timing map is pretty easy. The rest of the time tuning is spent optimizing fuel, air (boost and idle air), and timing under ALL levels of ambient temperature and engine load, which is exceedingly time consuming even for professionals.

I'm going to throw out a bunch of 3/S specific questions and maybe somebody has at least some information to share.

1st question: Where are you guys locating your IAT sensor? In the intercooler pipe before the throttlebody? Do you notice a problem with it heatsoaking after shutting it off, and then the IAT table leaning out the car until the temperature stabilizes?

2nd question: Does the AEM basemap have decent maps (for the VR4) for the accel and decel functions? Is tip-in hesitation a common problem? One of the things I like about the AEM is that it has accel vs. coolant temp correction. On my Power FC, you couldn't adjust tip-in vs coolant temp so it would use more accel fuel than I would like until it reached operating temp.

3rd question: The Idle air control stepper motor: are people keeping this? Do you have to adjust the park position in the AEM or any of its functions to prevent stalling on deceleration? Is idle control difficult on aggressive cams with unstable vacuum signals?

4th question: The AEM closed loop boost control--does anyone use the PID controller and tune the gains with any success, or are you just using the base duty map?

5th (and last): are there any common issues with getting the ignition timing on the AEM ems to be fully accurate (as in, match what the timing light says? can you even put a timing light on anything but an SOHC model?)? I'm not so familiar with the ignition system on the turbo models, but I think it uses some kind of magnetic pickup. Obviously there is no distributor to adjust.

6th (and last): how is the AEM for logging 0-5v inputs? I was thinking about running dual 0-5v EGT's (get a K-type thermocouple to 0-5v converter) and dual 0-5v backpressure gauges, with of course dual channel wideband (this type of setup is run on Rx-7's with Haltech's and Power FC's). So at most it would need 1 pulsewidth modulated output (EBC), 6 0-5v inputs, and a switched +12V output for nitrous.

Sorry for the uber technical questions.

[mjannusch]

Originally Posted by arghx

1st question: Where are you guys locating your IAT sensor? In the intercooler pipe before the throttlebody? Do you notice a problem with it heatsoaking after shutting it off, and then the IAT table leaning out the car until the temperature stabilizes?

Yes, in intercooler pipe before throttle body. Don't notice any trouble with it heatsoaking on my car. If it starts out hot, the air in the pipe is hot too. As soon as air starts flowing it goes down with the air temp.

2nd question: Does the AEM basemap have decent maps (for the VR4) for the accel and decel functions? Is tip-in hesitation a common problem? One of the things I like about the AEM is that it has accel vs. coolant temp correction. On my Power FC, you couldn't adjust tip-in vs coolant temp so it would use more accel fuel than I would like until it reached operating temp.

In almost all cases you'll need to tweak accel/decel fuel to suit your car. Not difficult to adjust, just takes some time to get it right.

3rd question: The Idle air control stepper motor: are people keeping this? Do you have to adjust the park position in the AEM or any of its functions to prevent stalling on deceleration? Is idle control difficult on aggressive cams with unstable vacuum signals?

Most people keep it. Easily tuneable and adjustable. I set the target/rpm table a bit higher than needed and then the fuzzy logic steps it closed until it hits the idle target. Works good, never undershoots. Control is fine on my DR street grind cams, have tuned a car with more agressive cams and you just need to keep idle high enough where it can be stable. His ended up set for 1000 rpm, but it could've been at 900 rpm and been fine. The vacuum signal doesn't matter that much as long as your fueling isn't wacky.

4th question: The AEM closed loop boost control--does anyone use the PID controller and tune the gains with any success, or are you just using the base duty map?

I prefer a separate boost controller unless you are trying to do per-gear boost control. Otherwise you can't change boost without hooking up a laptop.

5th (and last): are there any common issues with getting the ignition timing on the AEM ems to be fully accurate (as in, match what the timing light says? can you even put a timing light on anything but an SOHC model?)? I'm not so familiar with the ignition system on the turbo models, but I think it uses some kind of magnetic pickup. Obviously there is no distributor to adjust.

No real issues. You can hook an inductive timing light's clamp over a spark plug wire and see the timing marks just fine. Set the sensor delay value according to sensor type (about 50 microseconds for early-style optical sensor, about 130 microseconds for later-style hall-effect magnetic sensor) and then correct the offset to see accuracy at low rpm, then try high rpm to validate the sensor delay setting and you are done.

6th (and last): how is the AEM for logging 0-5v inputs? I was thinking about running dual 0-5v EGT's (get a K-type thermocouple to 0-5v converter) and dual 0-5v backpressure gauges, with of course dual channel wideband (this type of setup is run on Rx-7's with Haltech's and Power FC's). So at most it would need 1 pulsewidth modulated output (EBC), 6 0-5v inputs, and a switched +12V output for nitrous.

Works fine. Not sure how many 0-5v inputs are available unless you start unhooking other stuff. Not sure why you'd need backpressure sensors - it isn't real variable given certain operating conditions, and not something you can correct via ECU tuning. I'd skip those unless you are testing various styles of exhaust systems or turbines, or something along those lines.

Hope that helps...