chip guys - water/meth injection

[xhaust50]

After reading through several of Andy's posts about the DSMchips they seem pretty convenient and efficient. I am thinking about getting one, but I was also interested in adding water/meth injection to combat knock and cool intake temps. It would probably turn on around 8ish psi. My question is, is there any way to design a chip with this in mind? I know Andy preaches adjusting the FP for different octanes, but I don't think this would work as you would only need to adjust the A/F ratio at certain RPM's. Anyway to do this successfully? Or would you ultimately need an SAFC anyway to adjust for when the water/meth sprays?

 

[RayPeters]

If you're using just water, there won't be much of an A/F ratio change, but if you start adding meth you'll need a reliable means to remove an appropriate amount of gasoline. A MAFT will do that, it is more difficult with a S-AFC because while you can pull/add fuel with it, you risk a dangerous lean condition if the meth system doesn't spray.

 

[xhaust50]

Wouldn't a MAFT only allow you to richen or lean the entire RPM band? Wouldn't it work similarly to an AFPR? I will probably be using a 50/50 washer fluid mix.

I would think that I would either need something that can control A/F at specific RPM's, or I would need to have the water injection come on as soon as the boost kicks in. What is everyone's take on this?

 

[My91TalonTSi]

If you're using just water, there won't be much of an A/F ratio change, but if you start adding meth you'll need a reliable means to remove an appropriate amount of gasoline. A MAFT will do that, it is more difficult with a S-AFC because while you can pull/add fuel with it, you risk a dangerous lean condition if the meth system doesn't spray.

What are the chances the meth system doesn't spray? Most of the systems I have seen are pretty reliable. I always thought there was just as much of a chance as a fuel injector failing or a fuel pump.

 

[fwdeclipse]

Just as an example my boost switch went out on mine, which caused it not to spray. Good thing I was watching my knock guage and noticed or it could have been trouble.

 

[My91TalonTSi]

Just as an example my boost switch went out on mine, which caused it not to spray. Good thing I was watching my knock guage and noticed or it could have been trouble.

So I guess it's not that uncommon then. Thanks for the real life info.

 

[PieEyedPiper]

Interesting discussion.

I, not knowing much about it, am curious to know why a DSMchip wouldn't be sufficient for a washer fluid injection setup.

i.e.
-car runs @ 18psi
-water injection comes on @ 8psi
-A/F is set for 11:1 or whatever in the ECU

Would the ECU not self adjust the A/Fr's back up to 11 after the water injection came online?

I'm just saying if the computer can adjust fuel settings on its own to better match a target AFR then how come you can't just throw a moderate amount of washer fluid at the equation and leave the ECU to adjust to the target AFR?

Your patience is appreciated,

 

[xhaust50]

I don't think the A/F ratio is "set" by a chip. That is to say, I do not believe the chip commands a certain A/F ratio. Rather, the chip maker plays around with the fuel maps knowing your MAF and injector size to try to have the end result be a certain A/F ratio (ofcourse, I could be wrong).