SAFC low throttle tuning?

[dok33]

I'm having issues with my car running pretty lean at idle/cruise (17-19:1), probably due to the 680s and E85 (720s would have been a better fit but I got the 680s cheap) and I'm getting some surging at low throttle. I've got the base FP at 45psi with the vac line off, any more pressure doesn't richen the idle mixture anymore and I don't really want to run more than that anyways.

I was thinking about trying to adjust the low (0%?) throttle settings on the SAFC to try and richen it up a little, but I've read conflicting things. Right now I've got low zeroed out at 69% throttle and high at 70%.

Will this help at all or will the TCCS just adjust it out? Car is running really good otherwise, spinning thru 3rd is alot of fun:evil2:

 

[2yoduhJZ]

First off, why in the world are you trying to run 680cc injectors on e85 with just an S-AFC? it's not even a S-AFCII (you never stated 2nd edition which has 16 points of adjustment instead of 8 on the SAFC-I). SAFC's are very crude tuning instruments and you should be using a standalone. If you really wanted to use the SAFC as your tuning method you should ask a professional to tune your car correctly with a wideband AFR meter and since you have two files to choose from on the SAFC, do a tune for pump gas then another for your e85 setup.

 

[dok33]

Got a wideband and the capability to tune on my own no prob, just tryin to get some input on the low throttle stuff. Think I found what I needed, been tweakin stuff and have it runnin pretty good.

 

[suprahero]

my low throttle on my safcII was at 25% and less.

 

[figgie]

Dok33

something is not right.

You are running the lexus AFM + 660 injectors or some other system?

assuming that you are Lexus AFM. The 660 injector will make you run lean on E85 as just with basic math, I came up with 550cc/min x 30% = 165cc/min + 550cc/min = 715 cc/min to be 30% more. The 660 are short by about 8% which would show on the AFR as being lean. Only way to richen that up would be to adjust the low throttle portion by richening that up. That is not necessarily a bad thing btw as the timing curve will be affected through out.

Now. This assumes that the idle portion is not under close loop. If it is under closed loop then you can adjust but the tccs will adjust around your adjustments to get it back in line. A loosing battle

 

[dok33]

My injectors flow tested out at 690cc, 720s would be a better fit based the math I initially did (and yours), I may end up goin with 800s to get some more overhead. And ya, running the Lex AFM so with 720s on E85 it should run like it would on gas with 550s.

Since posting this I set the low throttle setpoint at 25% (based on info I found on SF) and adjusted the idle with the AFC. Helped alot, but I'm still having issues with the car running crappy after a fresh fillup due to crappy mixture control with E85 batches. TCCS seems to be leaving at least the idle settings alone, some people on the "other" forum have had pretty good luck tweaking it with the AFC.

Unfortunately my LC-1 has stopped working and I need to send it back to be reflashed so no tuning for a week or so

 

[figgie]

damn,

LSU 4.2?

 

[dok33]

Yea, I was having some issues programming the analog outs so they recommended flashing new firmware on it. Flash failed and it stopped working, apparently the only solution is to uninstall the damn thing and send it back in so I gotta undo all the wiring (horay).

 

[ihiryu]

Hey dok, hate to bring this back, so you are tuning idle by setting the AFC to 25% on the throttle setting? I haven't even touched the low, cause I'm afraid of vF.

 

[dok33]

Yup, and I also used it to smooth out my low rpm curve with no issues.

 

[ihiryu]

nice, i'll have to try that once I get my car up and running correctly. I went ahead and got some IS coils, too btw, I'll let you know how that goes. Oh I sent you a PM btw.