[Krypton1le]

Hello - I recently installed an ADM lt4 s/c kit onto my 2017 SS 1LE. I'm in the process of installing an AEM Failsafe gauge in order to monitor AFR and Boost. The gauge (as told by the name) can "activate a user-defined failsafe strategy if it runs lean". Has anyone used this feature and if so, how did you implement it? I'm having trouble thinking of a "failsafe" that I can activate to save the engine in the case it runs lean.

[TMS]

Originally Posted by Krypton1le

Hello - I recently installed an ADM lt4 s/c kit onto my 2017 SS 1LE. I'm in the process of installing an AEM Failsafe gauge in order to monitor AFR and Boost. The gauge (as told by the name) can "activate a user-defined failsafe strategy if it runs lean". Has anyone used this feature and if so, how did you implement it? I'm having trouble thinking of a "failsafe" that I can activate to save the engine in the case it runs lean.

I can't speak to AEM's failsafe gauge but I run their Infinity ECU and their engine protection failsafe strategy focuses on cutting fuel and/or spark in these lean conditions. For this ECU, the lean conditions are user defined in a 1D table that basically target an upper limit threshold lambda/AFR value at a given MAP value (kPa or InHg or PSIg).

So for instance, at 125 kPa I have a lambda trigger value of 0.95. If my actual lambda goes higher (leaner) than 0.95, then the protection kicks in by cutting fuel and/or spark.

I'm sure they use a similar strategy for their gauge. If you don't already have it, you can download their configuration software for the gauge from their website.


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[Krypton1le]

Thanks for the info TMS! I assume the Infinity ECU is a stand alone or piggy back? That's the only way I can imagine it working. Since my gauge has no connection to the vehicle ECU - there is no way for it to directly communicate.

I was trying to think of indirect ways to trigger a safety such as interrupting a sensor signal to the ECU that can then be calibrated in HP Tuners. For example, if the MAP sensor is "disconnected" via a relay of some sort - it should default to some value - you can then adjust fueling/timing based on that default value. However, running a sensor through a relay could impact resistance / voltage and give an incorrect value and I prefer not to hack apart my harness trying to find a good method lol

[TMS]

The Infinity is a standalone ECU.

I think you hit the nail on the head. While you can use the gauge to trigger an event such as a ground signal, that event/signal would need to be interpreted by the ECU to then control fueling or ignition or spark. Seems like that feature of the gauge is geared more for aftermarket controls rather than cleanly interfacing with factory ECUs. Interesting quandary.


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[Krypton1le]

Yes exactly - I bought the gauge primarily for the visual readings, not the actual failsafe features. So, the gauge is still valuable to me without it. I just thought it would be fun / interesting to implement the fail safe feature since it has it!

[SLO-GOAT219]

Originally Posted by Krypton1le

Yes exactly - I bought the gauge primarily for the visual readings, not the actual failsafe features. So, the gauge is still valuable to me without it. I just thought it would be fun / interesting to implement the fail safe feature since it has it!

That gauge usually works very nicely paired with a boost controller on a turbo setup.

That being said maybe you can use it with the oem style blower setup kinda like its used with aftermarket turbo setups.

With turbo deals it would send a signal to your aem boost controller or other brand that can read an input and tell the boost controller to return to only making wastegate pressure.

You may be able to wire the fail safe to open the boost bypass valve on the blower essentially doing the same thing. It all depends on how that valve works.

Now i don't know for sure but if the solenoid on the blower is just an on/off 12v switched valve and the aem fail safe can send a 12v trigger then you could wire the fail safe right into the bypass solenoid to trigger it.

If the fail safe is only able to send a ground signal you could possible have it grounding a additional relay out that then sends 12v to the blowers bypass solenoid.

[Krypton1le]

I believe it only sends a ground - its meant to work with an additional relay.

Unfortunately, the setup does not use an electronically controlled bypass valve - its actuated using vacuum. Since a blower is mechanically connected to the engine, you really can't run into a high boost situation - unless your pulley is too small. The bypass valve is really just there to help with idle conditions as far as I can tell.

[TMS]

Originally Posted by SLO-GOAT219

That gauge usually works very nicely paired with a boost controller on a turbo setup.

That being said maybe you can use it with the oem style blower setup kinda like its used with aftermarket turbo setups.

With turbo deals it would send a signal to your aem boost controller or other brand that can read an input and tell the boost controller to return to only making wastegate pressure.

You may be able to wire the fail safe to open the boost bypass valve on the blower essentially doing the same thing. It all depends on how that valve works.

Now i don't know for sure but if the solenoid on the blower is just an on/off 12v switched valve and the aem fail safe can send a 12v trigger then you could wire the fail safe right into the bypass solenoid to trigger it.

If the fail safe is only able to send a ground signal you could possible have it grounding a additional relay out that then sends 12v to the blowers bypass solenoid.

Clever thinking. Assuming the ADM setup is all LT4 OEM stuff, the bypass valve is vacuum actuated though.

EDIT - Sorry, I missed Krypton1le's post. What he said.

[TMS]

OK how about this for outside the box thinking? So go easy on the thought process. I can't connect all the dots in my mind but if you are NOT running E-85, maybe you could leverage the E85 tables in the ECU. Since we are talking about fuel and timing control for failsafe perhaps you could install an Ethanol sensor and wire it into the ECU. Then you use the gauge failsafe trigger as a means to send the right voltage signal to the E-85 sensor to make the car think it's running a different Stoich based on the sensor read. Basically instead of adding timing and fuel you pull timing and fuel on the E-85 side of the equation in the appropriate tables.

Just thinking out loud.

[McBrayer]

Use the "fail safe" ground to control a normally closed relay. Wire the relay contacts into one of the throttle peddle position sensor wires.

Go lean, cuts throttle, problem solved and you do not have to do any wiring outside of the cabin.

Be advised that this could cause a check engine light and or limp mode, but it can easily be reset with a code reader.

[Krypton1le]

Is this something you did McBrayer? I'm not saying it wouldn't work - there are just things I hesitate to splice into and pedal position is up there on the list lol. If the relay circuit alters the resistance in the pedal position circuit, you're going to be going for an interesting ride.

[SLO-GOAT219]

Originally Posted by Krypton1le

I believe it only sends a ground - its meant to work with an additional relay.

Unfortunately, the setup does not use an electronically controlled bypass valve - its actuated using vacuum. Since a blower is mechanically connected to the engine, you really can't run into a high boost situation - unless your pulley is too small. The bypass valve is really just there to help with idle conditions as far as I can tell.

Well shit....i was onto sunthin I thought haha. I was just assuming the bypass was pcm controlled via a valve and vacuum. Most things like that on newer cars are ran by pcm. Guess not in this case lol

I know on my 2016 VW the BOV is actuated by vacuum still but the pcm tells it when to. Sometimes at real light throttle going up a slight grade you can hear the pcm opening the bypass for w/e reason. Sounds like a procharger race valve lol. The pcm in that thing will also use it for torque management and traction control. You can be WOT and this thing will just blow off all ur boost till it shifts and stops spinning so bad.

[SLO-GOAT219]

Originally Posted by TMS

OK how about this for outside the box thinking? So go easy on the thought process. I can't connect all the dots in my mind but if you are NOT running E-85, maybe you could leverage the E85 tables in the ECU. Since we are talking about fuel and timing control for failsafe perhaps you could install an Ethanol sensor and wire it into the ECU. Then you use the gauge failsafe trigger as a means to send the right voltage signal to the E-85 sensor to make the car think it's running a different Stoich based on the sensor read. Basically instead of adding timing and fuel you pull timing and fuel on the E-85 side of the equation in the appropriate tables.

Just thinking out loud.

You may be able to do something similar to this with the IAT signal. When IAT signal was lost on older gm cars it would read like it was at the lowest temperature possible. So in that part of the iat spark adder table you could make it command like 5* of advance only. It will be part of the table that the actual iat readings would only ever actually go if it was like -30* outside so it will more than likely never hit that temp in real world use. Only when the fail safe grounds it out or cuts the signal going to the pcm thus causing the pcm to go to the minimum reading on the table.

I know guys have used it with aftermarket 2 step systems. When they hit the button it sent ground to the 2step tp tell it to work and grounded the IAT circuit i do believe as well to make it got to the lowest part of the table where they would retard the timing a bunch to help build boost on the trans brake while the 2step was active. When they would let go of the button the IAT would return back to normal operation and timing

[ZNix]

https://www.lingenfelter.com/product/L460145297.html

Little more expensive, but the box has other uses. Setup the AEM Failsafe to trigger a timing retard.