Low/High Boost Switch

[Stephen@NCAutoUSA]

When you wire in a toggle switch and tune it's one tune from my understanding.

You wire into a pin from the aem harness "something that's not used"
Then that wire goes to a switch
Then the other side goes to a ground.

For example if your wastegate spring pressure is 8lbs that's your low boost, if you have a 10lbs spring then that's the low boost.

When the switch is turned off meaning no signal is going to ground and that pin is not activated then it will be at the tune you were tuned at. For example 16 psi or even 20psi on the eletronic boost controller.

If the pin is activated and goes to ground then that over rides the eletronic boost controller and it turning on.

It's not 2 different tunes, it's the same high psi tune but the springs just opening and that's what your running off of. I know this is one way, maybe you guys have a different way to hold 2 seperate tunes but I always thought you needed a seperate boost controller for that.

 

[OKI-BOY]

Excuse my ignorance, I didn't know there was a difference between tunes and maps.
I just know that there is a difference between pressing the button and not, so I would assume there being a difference,
that it was a different map/tune.

Thanks for the education.

 

[Stephen@NCAutoUSA]

No it's cool. I don't know exactly either that's why I started the thread, haha.

I just know what my tuner told me and what elogic has said and I believe what Chris talked about on the phone with me awhile ago. But some of these conversations I had with individuals I didn't 100% comprehend at the time so I could be wrong what I posted.

And also considering I'm running an old aem ems, you guys could have a newer version that allows certain features. I'm still trying to figure it out. That's why I posted the above sequence if events.

 

[Hugh]

Hugh. Is it 8 lbs off strictly your wastegate spring pressure just eliminating your target psi from your electronic boost controller?

I honestly have no clue. But I will find out.

 

[Maximumyield]

I have a low/hi boost switch working correctly for many years now AEM 1042. It is defined as a low/hi switch but your HI is actually your max boost you set your map for and low boost would operate from the same map tune, but limiting the boost to a set lower number. So you would tune your car with max boost in mind. I use the AEM EMS for boost control not a external controller like trueboost or anything.

Example, car is tuned to 14psi max boost, then in hi/low boost settings in AEMPRO choose the switch # mine #3 gnd/on and set the boost to say 10psi. On HI boost it will run 14psi, your maximum boost. Low boost is just a lower amount of controlled boost from the same map when the switch is activated it would decrease boost by 4psi to 10psi using the same 14psi map.
I used a relay with my hi/low switch as it was putting +12 volts out, so a 12v 30a 5 pin relay came in handy to send a -neg signal reversing the output from the switch to a neg - as AEM uses a swiched ground for this signal.

I believe you may not be able to do this with your older AEM EMS, Mine is a 1042.
Here is my tip, I went through all this before. It would not work no matter what I tried(many hours). I spoke to Ed at AEM and after days of research we came to the conclusion it was the version of the AEM, it was a 1042 but earlier one I guess.. I had firmware rev A I believe and he found out that this option would not work without a firmware upgrade to the current at the time rev C, I believe. Sent it off to AEM, they updated it and I was already wired from the weeks of trial and error I had figuring this out. Put my tune on it set the switch up and it actually worked for the first time and still works perfect today.

This is why I do not think the older AEM will work(my opinion). Possibly it can ? AEM is your only answer on this I believe or maybe some shops, but they seem to be confidential on these things.

I would start with AEM, firmware revision and see if the older 1002 I believe has a firmware update to fix this like it did in the 1042. See if the 1002 has the same firmware update as the 1042.
Hope this helps some and puts you in the right direction to your final answer.
Oh and I do not believe my switch is actuating just the spring / no spring for hi/low. It is controlling the solenoid / wastegate still at lower boost. low/hi switch is like a rev limiter but for boost.
All the low switch does is cuts max boost and Hi is just max boost your map is set for.
If you use the nitrous option then your map can be changed with a switch for fuel and ignition changes and can be used with the hi/low boost option, but you will not need this unless you are running nitrous, methanol or what it may be.

 

[E-Nough Logic]

From my tunes when I run race gas I only run a single map. What I do is on the single map I run more aggressive timing only on the boost levels that I run race gas on and I run more conservative timing on the boost levels that I run pump gas on. The fuel maps don't really need to be change because race gas and punk gas both need the same amount of fuel, so even when you're just cruising around part throttle your air fuel ratio should be pretty much the same with both gases. When I'm on race gas the boost levels are virtually never in the pump gas area anyway so it's not even really a factor. It would really depend on the application and what your exact requirements are though. Setting up two different boost cuts can be somewhat tricky but it is possible.

Maximum, what problems were you having, was it just not reading the input at all or was it just not switching the boost levels? I've got a 1002 box, and I have no problems with reading the inputs but I'm not controlling boost though.

 

[Maximumyield]

From my tunes when I run race gas I only run a single map. What I do is on the single map I run more aggressive timing only on the boost levels that I run race gas on and I run more conservative timing on the boost levels that I run pump gas on. The fuel maps don't really need to be change because race gas and punk gas both need the same amount of fuel, so even when you're just cruising around part throttle your air fuel ratio should be pretty much the same with both gases. When I'm on race gas the boost levels are virtually never in the pump gas area anyway so it's not even really a factor. It would really depend on the application and what your exact requirements are though. Setting up two different boost cuts can be somewhat tricky but it is possible.

Maximum, what problems were you having, was it just not reading the input at all or was it just not switching the boost levels? I've got a 1002 box, and I have no problems with reading the inputs but I'm not controlling boost though.

^^^ With everything hooked up right and before the AEM firmware update, it would just stay at Max boost, would not cut/limit to 10psi.
The hi/low boost activation was not working in the older revisions as far as I know. The new rev C firmware updated that switched input to activate and actually do what it was supposed to.
Boost level would just stay at max, like it was not even hooked up before the update.
Maybe it was a 1042 prob only if yours works on the 1002?