who's using fuel trim controllers?
 

i'm talking about things like an like an AFC or map-ecu or HKS fcon, greddy e-manage, etc. one of these things plus a wideband o2 sensor could go a long way. when i get in my other car we use these things for more HP. but it all boils down to efficiency. i see no reason we can't use these things for improved fuel economy.

Well there are few guys running custom chipped hondas. "DRW" is running a custom chip in a DSM. "Coyotex" is running some type of wide band and a megasquirt I think. Lastly there are a few guys running an EFIE or something like it.

Thats all I know of.

My CRX is chipped, :p

my problem with the EFIE's and the IAT resistors is that they change the fuel curve across the board. i really only want to lean it out at low RPM and low TPS.

the other thing is, how do the fuel trim computers work if the ECU tries to compensate for AFR readings it is not expecting? suppose i do manage to lean it out, the ECU is going to see that it is lean and start adjusting the long term fuel trim eventually zeroing out the piggyback fuel controller.

Well I would think that the EFIE would not change the fuel curve for WOT because most cars would go into open loop thus negating the input of the O2 sensor. This is kind of an untested ground for gassavers because its difficult to get a decent return on your investment. There are cheaper ways to get the same mileage.

At WOT the computer calculates the required fuel delivery using IAT and airflow, which is why adding to or bypassing the IAT resistance changes WOT mixture.

lovemysan -

I am assuming that you mean EFIE when you are talking about ROI. They seem to start at $50+, so I think they have decent ROI.

The fuel trim controllers are harder to justify because they seem to run $200+. But since they are geared for performance, they are like a 2 for 1.

jiggersplat -

I have my own plan for my EFIE. Right now it is on a switch. When I go over 25 TPS on my Scangauge, I turn it off. What I want to do is make it so that there is a relay that uses the TPS voltage to *automatically* turn off the EFIE when the throttle is greater than 25 TPS. That way, the car won't run lean when I need the power.

CarloSW2

that is an interesting idea. if i understand correctly, the EFIE tricks the car into thinking it's running richer than it really is by adding voltage to the o2 sensor signal. the cars ECU then compensates by setting the long-term and short-term trims. the only thing i would be concerned about is your car's ECU setting long-term and short-term fuel trims and not adapting fast enough when you switch it off. perhaps i don't know enough about how modern ECUs calculate fuel requirements.

can anyone link me to a post with some quantified results from using the EFIEs?

jiggersplat -

I've got one running now, with my own non-professional musings on what I am seeing :

Eagle Research EFIE Online ...
https://www.gassavers.org/showthread.php?t=5036

I made a youtube of the digital A/F ratio responding. What I *really* need to do is make a longer youtube of the same, but in a context that is not just idling in a parking lot.

In terms of hard numbers, I'm sorry to say that I can't provide them (very not cool!). This is one reason why I really need to get the elmscan. If I can datalog the fuel trim and 02 sensor reading (not available on my Scangauge I), then I will be in a position to provide those numbers.

CarloSW2