Help on HSW Interface Controller and A/F adjustment
Thread Starter
Burning Brakes
Joined: Nov 2008
Posts: 862
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From: Gaithersburg MD
Help on HSW Interface Controller and A/F adjustment
I am posting this on the FI forum as well in hope for an answer.
I sent this question to HSW about their Interface Controller product:
How does the Interface box change the fuel flow in a dry system with injectors after the MAF? Would like to know which tables in my 09 LS3 C6 to change. Seems like I would change the Injector flow rate vs IAT table and enter smaller numbers to make the system flow more fuel at the higher IAT that the Interface is simulating.I got this answer:
Nothing needs to be changed for A/F as the Interface uses the MAF signal.I sent this follow up question:
I sent this question to HSW about their Interface Controller product:
How does the Interface box change the fuel flow in a dry system with injectors after the MAF? Would like to know which tables in my 09 LS3 C6 to change. Seems like I would change the Injector flow rate vs IAT table and enter smaller numbers to make the system flow more fuel at the higher IAT that the Interface is simulating.
Nothing needs to be changed for A/F as the Interface uses the MAF signal.
Sorry but I must not be making my concern clear.
The stoichiometric A/F for a N2O/gasoline mix is 7.0 not 12.7 as it is for air/gasoline. The combined stoichiometric ratio for a partial N2O and air mix is a function of the size of the shot. In my case I have about 500 bhp without N2O and want to add a 150 bhp shot. This will result in a need to target a combined A/F ratio of about 11.38.
So somewhere the ECM needs to be tricked into increasing the injected gasoline to reach the correct combined A/F ratio.
How does this happen in the HSW Interface? It does not know what HP I have without N2O, only that I want a shot of some size.
Also don't see how it knows if I have a dry vs. wet system, nor if I have a dry nozzle is before the MAF or after, or if I have one pointed at the MAF or not, etc.
I have HpTuners MPVI Pro and an WBO2 sensor and will want to make sure that the A/F is correct during the N2O injection. So I want to know how the HSW Interface is going to trick my ECM into correctly adjusting the metered gasoline flow.
Only thing I could guess is to change the injector flow rates for the higher IATs that the HSW Interface is simulating (see original attachment). I do not want to take this path if the Interface is already taking some other approach to correcting the A/F during the N2O burst.
IMHO, there must be much more to the fuel flow control than is being implied by the instructions.
Perhaps you have an application note on the topic?
Sorry for the long post. Does anyone have specific experience using the HSW product on a E38 ECW and knows the answer to my question?
The stoichiometric A/F for a N2O/gasoline mix is 7.0 not 12.7 as it is for air/gasoline. The combined stoichiometric ratio for a partial N2O and air mix is a function of the size of the shot. In my case I have about 500 bhp without N2O and want to add a 150 bhp shot. This will result in a need to target a combined A/F ratio of about 11.38.
So somewhere the ECM needs to be tricked into increasing the injected gasoline to reach the correct combined A/F ratio.
How does this happen in the HSW Interface? It does not know what HP I have without N2O, only that I want a shot of some size.
Also don't see how it knows if I have a dry vs. wet system, nor if I have a dry nozzle is before the MAF or after, or if I have one pointed at the MAF or not, etc.
I have HpTuners MPVI Pro and an WBO2 sensor and will want to make sure that the A/F is correct during the N2O injection. So I want to know how the HSW Interface is going to trick my ECM into correctly adjusting the metered gasoline flow.
Only thing I could guess is to change the injector flow rates for the higher IATs that the HSW Interface is simulating (see original attachment). I do not want to take this path if the Interface is already taking some other approach to correcting the A/F during the N2O burst.
IMHO, there must be much more to the fuel flow control than is being implied by the instructions.
Perhaps you have an application note on the topic?
Burning Brakes
Joined: Feb 2008
Posts: 988
Likes: 2
It fools the MAF into thinking it is receiving more Air when you are at WOT. Thus it adds more fuel.
So lets say at WOT you used to read 5000 hertz through the maf... well now it will read 6000. (Not necessarily the real numbers, but just an example.) So your injectors will now spray more.
If you have a wet system, there is no need to have the interface unless you want to reduce timing when running juice without having to retune.
You configure it via switches in the interface to the size of the shot and how much timing to pull... and the delay from it activating from the time your N2O activates. You can configure it to add no fuel if you just want to reduce timing. You can configure it for most shots.
The only thing you need to look for is if you have a tune and the IAT table was modified. You'll need to know where on the IAT table it pulls the certain degree of timing that you'd want it reduced by.
So lets say at WOT you used to read 5000 hertz through the maf... well now it will read 6000. (Not necessarily the real numbers, but just an example.) So your injectors will now spray more.
If you have a wet system, there is no need to have the interface unless you want to reduce timing when running juice without having to retune.
You configure it via switches in the interface to the size of the shot and how much timing to pull... and the delay from it activating from the time your N2O activates. You can configure it to add no fuel if you just want to reduce timing. You can configure it for most shots.
The only thing you need to look for is if you have a tune and the IAT table was modified. You'll need to know where on the IAT table it pulls the certain degree of timing that you'd want it reduced by.
