Using msd 2 step for a fail safe in a lean condition
Thread Starter
Joined: May 2012
Posts: 1,796
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From: Elm Creek, NE
Using msd 2 step for a fail safe in a lean condition Hello all, I'm looking at buying the Aem fail safe gauge, and when it sees a lean condition it ha a wire that grounds and you can use it to trigger whatever you want. Initially I was going to try and use it to ground the iat and change the timing at the extreme that that triggers to cut timing in half or something. But I was informed that the iat stuff is slow reacting and likely wouldn't do what I want. So, next theory. My 2 step is able to be activated by 12v positive or 12v negative. I'm using 12v positive combined with a a trans brake to activate it now. But, I could use the ground wit hooked to the aem and trigger the 2 step in a lean condition. Would this be safe on the engine? The next step is putting another selonoid inline with the compressed air so it drops back to gate pressure. I could do this, BUT using the 2 step would be much much simpler.
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From: Ohio
Hello all, I'm looking at buying the Aem fail safe gauge, and when it sees a lean condition it ha a wire that grounds and you can use it to trigger whatever you want. Initially I was going to try and use it to ground the iat and change the timing at the extreme that that triggers to cut timing in half or something. But I was informed that the iat stuff is slow reacting and likely wouldn't do what I want. So, next theory. My 2 step is able to be activated by 12v positive or 12v negative. I'm using 12v positive combined with a a trans brake to activate it now. But, I could use the ground wit hooked to the aem and trigger the 2 step in a lean condition. Would this be safe on the engine? The next step is putting another selonoid inline with the compressed air so it drops back to gate pressure. I could do this, BUT using the 2 step would be much much simpler.
Thread Starter
Joined: May 2012
Posts: 1,796
Likes: 59
From: Elm Creek, NE
What difference would it be then say being late on a shift and hitting the rev limiter? Factory the pcm pulls fuel, right? The 2 step pulls spark, so if I have a lean condition, pulling spark would surely fix that lean condition instantly and get my attention lol.
Thread Starter
Joined: May 2012
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From: Elm Creek, NE
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From: Ohio
Send the IAT wire through the NC circuit on a 5-pin relay. Give the relay power. Let the ground activate the relay and disconnect the IAT completely. It'll default to the coldest part of the IAT timing table. I've used it for antilag.
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I would think dumping the boost would be better then retarding timing due to a lean condition. If you just retard the timing its still lean just woth retarded timing. If you dump boost that will actually effect the lean condition. Plus say you are tuned to 12 degrees at a certian boost and it retards the timing ten degrees it would be like anti lag at full power. Doesnt seem it would be good for things in my opinion. Maybe im wrong but id go boost dump.
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Verdad Gallardo Restricted User
Joined: Mar 2014
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From: Ohio
Boost responsiveness is very slow, which is why its not used for traction control by aftermarket PCMs. You have to send the signal to the controller, have it open/close a solenoid, change pressure in the wastegate line, open the wastegate diaphragm, and wait for the turbo to slow down.
Timing or AFR adjustments would be the way to go. Making the IAT default to the coldest possible reading will also cause the PCM to add fuel to compensate. 2 birds, one stone.
Timing or AFR adjustments would be the way to go. Making the IAT default to the coldest possible reading will also cause the PCM to add fuel to compensate. 2 birds, one stone.
im just kiddin 
so on this topic, my boost controller has an overboost shutdown feature where if it senses manifold pressure over a set value it uses boost to pin the gate wide open...but that's not gonna help if the gate itself is having a mechanical failure.
i do just like joe says. works good to pull timing for a variety of things, running outta meth spray, if the tires are spinning. all sorts of stuff.
IME you have to pull like 25 degrees out to get an "anti-lag" effect.
just dropping 6 or ten degrees will nose the car over. in fact that's how I rev limit on the stock computer. max the fuel cut RPM and yank timing out after 7500 rpm
so on this topic, my boost controller has an overboost shutdown feature where if it senses manifold pressure over a set value it uses boost to pin the gate wide open...but that's not gonna help if the gate itself is having a mechanical failure.
i do just like joe says. works good to pull timing for a variety of things, running outta meth spray, if the tires are spinning. all sorts of stuff.
IME you have to pull like 25 degrees out to get an "anti-lag" effect.
just dropping 6 or ten degrees will nose the car over. in fact that's how I rev limit on the stock computer. max the fuel cut RPM and yank timing out after 7500 rpm
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https://ls1tech.com/forums/fueling-i...ed-engine.html
You can designate a bunch of parameters and have it cut power to the coils or ignition, etc. Works well. I still use it for oil pressure in all of my cars.