Hi Folks,

I am running a seq setup with BNRs and use 3 port mac valves for wastegate control and turbo precontrol. I'm using an AEM water/meth injection and pondering the best way to implement a limp / boost cut mode if the meth injection system reports an error (pump, low juice, etc.). The AEM system has a boost safe output that will enable in any of these error states... I am running a PFC, so there's not a bunch of fancy limp / power cut modes that I can have the ECU do (to my knowledge).

One idea I had was to use the signal to drive a relay to disconnect the wastegate control mac valve. This would result in full boost pressure driving the actuator and result in basically dropping to wastegate spring pressure - which I believe on the BNRs is 10 psi (I think stock is ~7?).

Another idea is to leave the hot side alone, and instead leverage the blow off valve - I could use the signal to switch the BOV to see the vacuum in the vacuum chamber which should result in it fully opening and dropping dumping boost.

How have other folks done this?

-j

 

Both of your ideas are great but the aem kit is extremely reliable. If you're using the supplied LED then its not going to throw you any curveballs. You also need to make sure to keep the filter clean and pull the nozzle apart for cleaning every so often as well. It wouldn't hurt to have the failsafes in place but its not really necessary.

Your tune shouldn't be so reliant on the meth to begin with that should there be a malfunction in its operation, it would be catastrophic. Of course do whatever makes you comfortable but you don't NEED the system in place especially with the status LED in use.

 

Totally agree, but I figured while I was at it, I might as well do something with the boost safe. I have wired up the status LED, and it's now a pinhole LED that's mounted right in front of the boost gauge in a way that it reflects back and is impossible to miss.

I also won't be running so aggressive a tune that it grenades if water injection doesn't go as planned... Honestly this was more the OCD of "I went to the trouble to run the boost safe wire into the engine bay, now what am I going to do with it..."


Boost Status LED is a 2mm recessed LED here (that you can't see unless it's on, and then it's super obvious)

 

I used the AEM failsafe signal (which can be changed in the AEM setup) to trip the second boost setting on the PowerFC or "valet mode", simply sending a ground signal. I set that second boost settings to completely come off boost. Pretty easy to do and pretty simple. There will be some delay in order for the boost to drop, if in boost, however.
Mike

 

Just seconding this. I’m not tuned with it and not very sophisticated. Low fluid level warning light and a green light to tell me the pumps on line. Done.

 

Question on your setup. Did you tune the car with the boost juice? Actually modifying the fuel and timing? Or did you have the car tuned and are adding the AEM on top?

I am running the AEM V1 with the V3 nozzle. I tuned the car without the boost juice, then added it back for cooling and cleaning benefits.

Also, while it has typically been reliable, the V3 nozzle did somehow get stuck SHUT. I took it apart a few times, without seeing any damage and it started working again. Then a few weeks later got stuck shut again. I spoke with the AEM technical department and they didn't have an answer as to why, especially if I drive a few thousand miles a year. Took it apart again and removed the check valve completely and have not had an issue since.

Moral of my story, for me, is that without a safeguard or more advanced ECU, I would not tune using boost juice just in case similar happens.

 

the early v3 nozzles had that issue. AEM fixed that relatively quick, not that they would admit to it. Don't....... but if you bought a v3 nozzle produced recently it wont have that problem.