so, when tuning for meth, you want to target the same lambda reading as before right? so if my afr was originally 11.2-11.3 on pump 93 only, then when i add meth, i still want to target that same lambda reading correct? the wideband doesn't know the difference between the two fuels so as long as it reads the same it should be good, this is my thinking anyways...

 

That is correct. Generally if you are tuning for meth, you add meth until the AFR increases by 1 full point. So if you were shooting for 11.7, you would tune to 11.7 on gas. Then add meth and stop when it is at 10.7. Then you would reduce the fuel until it is back to 11.7.

 

good advice, thanks.

 

just make sure you have some sort of fail safe. If the meth stops spraying you are going to be running lean

 

What type of failsafes are there?

 

And if your fuel pump or injector quits you will go lean also. To get the benefit of meth you will have to pull fuel or it will be too rich, if you pull fuel then naturally you know the risk if the meth fails.

 

agreed, IMO the chances of a meth kit failing is much more than a injector or fuel pump though

alot of people like to run washer fluids and such for water/meth kits , its known to gum things up over time and make them fail. If vehicle is turbo charged could have some sort of fail safe that opens the wastegate so it dumps boost, some have done timing retard, not sure if you can setup something through the computer with tuning on these trucks or not

 

You can split your MAF from your IAT sensor, have the meth spray before the IAT sensor, but after the MAF. Then set the tune to pull a lot of timing if IAT's climb too high. When spraying meth in front of the IAT sensor the temps on the sensor should be less than ambient.

 

I have mine setup the same as said above. Works very well!

 

The problem with that is reaction time due to sensor delay. Your engine would be toast before the IAT sensor heated back up enough to pull timing. Methanol coats the sensor in liquid form and then has to evaporate off the surface, which cools the sensor. The only real way to create a failsafe is give the PCM a signal instantly. This would be something like a hobbs switch that must see pressure from the meth system in boost and if it loses pressure, completes a circuit that puts a resistor in parallel with the IAT sensor circuit. This would prevent any sensor delay and save the engine. There are potential digital solutions as well, but they are more complex.