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shoes59
06-17-2006, 06:17 PM
A couple dyno pulls today revealed I'm running a bit rich from about 4000 rpm up. Should I reduce the fuel, advance the timing or both. I'll do whatever is recommended in small increments to play it safe.

Sorry for the newb sounding question but I can't recall the easiest way to lean it out a tad.

Gonad
06-17-2006, 06:24 PM
What kind of AFRs are you seeing at 4000rpm?

What gear?

You want to be in the 11.2 to 11.7 range at WOT to be safe from knock and other issues.

Things you can try:

- Adjust accelerator enrichment
- Adjust your fuel map (I used Enthalpy's base map and then cleaned it up to suit my AFRs)
- Water temp correction (you sure you haven't adjusted this too much ya?)

shoes59
06-17-2006, 07:23 PM
I'm seeing 10.9 - 11.1 a/f in both third and fourth gear WOT pulls. I wanted to bump it to around 11.7 -11.8.

s14rhd
06-17-2006, 08:10 PM
Water temp correction is a very easy way to do so, I assume you would be only going into 4krpms when its warmed up to 80 C.. Drop the temp corection at 80c down by about 5 so it will read .95 I assume you have it a 1.00 at the momnet. No responsibility taken for forked engines though.

XSDAILO
06-17-2006, 08:39 PM
Water temp correction is a very easy way to do so, I assume you would be only going into 4krpms when its warmed up to 80 C.. Drop the temp corection at 80c down by about 5 so it will read .95 I assume you have it a 1.00 at the momnet. No responsibility taken for forked engines though.

You could do it that way, but the better way to do it is to go into the PIM or MAF voltage screen (I forget since I rarely use the commander) and change everything from 4000rpm up to .95. This screen is kind of like a S-AFC built into the FC Commander.

If you are running a stock turbo, you should probably keep the a/f ratio around 11.5:1. On the 91 octane we have here in CA, any leaner than that and you're asking for problems. If you want it on the safe side run it in the low 11's. Also, if you are running the OEM Apex ignition timing map, you'll probably have to turn it down 3-4 degrees or so since that map is for Japanese 100 octane pump gas.

BlazedGlory
06-17-2006, 08:53 PM
- Adjust your fuel map (I used Enthalpy's base map and then cleaned it up to suit my AFRs)

What kind of mods do you have? I'm a tuning newb, but I'm almost done with my engine build, and I've been reading as much as I can about tuning theory to help me with my PFC. I was thinking about running Enthalpy's base map to start, and adjusting from there... Would this be ok to do even with a fairly modded engine? Have you yet to adjust the timing map at all?

Don't mean to steal the thread... We could use a real good PFC thread though with answers to a lot of stupid questions and help with more advanced stuff or something. I know I can't be the only one out there who would find it beneficial or at least a damn interesting read!

s14rhd
06-18-2006, 02:34 AM
Don't pay any attention to what I said you can't decrease the fuel only add it in the water temp correction at 80c.

Gonad
06-18-2006, 01:19 PM
BlazedGlory:
I have a stock SR20DET overall; the only mod is a top-mount T3/T04B turbo (with 2.5" elbow, 3" down/mid pipe, and 2.75" straight through exhaust)

I didn't use the factory map as much since I switched over to Enthalpy's base. Since then I've only had to correct his map a few places on the fuel map.

Most of my changes have been on the accelerator enrichment table.

It's almost a trial and error type thing unless you go to a shop. Have a buddy drive and you watch the commander in Map Trace mode to see where you are getting the kind of AFRs. That's how I have done it (except I do it alone using the ghost tracing mode).

I usually do 2nd and 3rd gear pulls to see what kind of #s I am getting.

KB240SR
06-18-2006, 05:30 PM
wouldnt 3rd and 4th gear pulls be best to do so the rpms go up more gradual than in 2nd gear or doesnt that really matter?

champa
06-18-2006, 05:45 PM
yeah 2nd gear is too fast. 3rd pulls is usually what i do. 4th if i have a long stretch of road.

it's better if you lean out the fuel within the fuel map instead of altering the water temp or PIM/MAF tables.

shoes59
06-19-2006, 10:00 AM
Thanks for your help guys. I have yet to tweak the parameters and give it a go but will let you know how I make out when I do.

FYI, I'm using Enthalpy's base maps tweaked ever so slightly from a dyno session done last year. I laid down 325whp @ psi on a Dynapack with a "conservative tune". This past weekend I had the car on a Dynojet expecting to see somewhere around 350-360whp but to my surprise I only put down 310. Nothing has changed other than switching to a slightly larger waste gate. On the Dynapack run last year I had the 02 threaded into the bung where the cat would be. On the Dynojet run I had the 02 positioned at the tailpipe.

What do you think is the cause for a lower hp number? Could one of the dynos be spitting out bogus numbers? Mods are GT3076, PB manifold, JGS 40mm WG, Tomei 740cc injectors etc., etc. With my set up I should be seeing more like 350whp on a Dynojet with a conservative tune, shouldn't I?

Blown240sx
06-19-2006, 10:15 AM
Dynos can vary in their output. Ive seen some that are off by as much as %15.

vosko
06-19-2006, 10:34 AM
you are expecting 350 @ what boost ?

BlazedGlory
06-19-2006, 12:48 PM
BlazedGlory:
I have a stock SR20DET overall; the only mod is a top-mount T3/T04B turbo (with 2.5" elbow, 3" down/mid pipe, and 2.75" straight through exhaust)

I didn't use the factory map as much since I switched over to Enthalpy's base. Since then I've only had to correct his map a few places on the fuel map.

Most of my changes have been on the accelerator enrichment table.

It's almost a trial and error type thing unless you go to a shop. Have a buddy drive and you watch the commander in Map Trace mode to see where you are getting the kind of AFRs. That's how I have done it (except I do it alone using the ghost tracing mode).

I usually do 2nd and 3rd gear pulls to see what kind of #s I am getting.

Well I guess the main thing I'm worried about is the timing map. I'm not really worried about the fuel at all, for I have an Innovate wideband setup and I got pretty good and tweaking a SAFC2 with the wideband as a reference. I guess I am pretty confident in being able to get the afrs correct, but I'm going to really need some sort of help with the timing. I don't know what to look for, I don't know what to change, etc, etc. With the fuel, at least I have a goal (around 11.5 or so) to shoot for, and the wideband will be a good reference. Does that make sense? Timing tuning eludes me at this point...

shoes59
06-19-2006, 01:33 PM
you are expecting 350 @ what boost ?
18 psi.