Results from my DE baseline

[slipnfall]

Hi folks, I finally got around to getting a baseline: see pictures below. Altitude here is around 5200', which really puts a damper on the output.

Factors:Stock rebuilt DE, ~20,000mi91 Octane21.5-22* base timingStock resonators(x3) removed

Accounting for 18-20% drivetrain loss, should put me around advertised spec.

My only concern is that it seems a bit lean: comments? I was blowing *something* out the exhaust 80% of the pull: black, but mist-like(not heavy smoke). Could this be mis-firing?

BTW my buddy dyno'ed his KA24E, with 140k and a cat-back. I'll try to get a copy of his and post here. His torque curve came on VERY sharply, and maintained that level throughout. However mine ramps up much slower, which I guess is attributed to his exhaust(2.25")

Cheers,Jamie

[slipnfall]

SAE

[trust068]

does anyone know why there is a dip at 3000 rpm?

[slipnfall]

Yeah like I said on my buddies SOHC, he immediately generated his pk torque(or close to it), at around 3k, and maintained it consistently. Mine ramps up. I'm not sure what the DE curve is supposed to look like.

[deviousKA]

Where was the wideband located? On the end of the tailpipe or? Any extra air that might get into the exhaust would lean the reading.

Does seem a bit on the lean side, compared to what ive seen others run. Not a bad a/f though.

The sohc builds more intake and exhaust velocity sooner that the dohc, this might be the difference you see in the torque curve.

Get that sohc sheet up! Or, is there some embarrassment involved?

[slipnfall]

lol, no it's not like that. However with 140k and just an exhaust, assuming 18-20% drivetrain loss, we calculated he gained ~8-10hp from the cat-back(it's an Apexi dual-style).

I didn't want to post his numbers up because I couldn't remember exactly what they were: ~92whp SAE IIRC. I just emailed him to ask for his runfile.

Wideband probe was aprox 12" up the exhaust: I have a stock muffler with the dual tips, so I don't think ambient air would have gotten in there easily. I was always under the impression that a wideband probe had to further up to be accurate.

From what I understand, the ECU is in open-loop at WOT. So the injector pulse width and timing are pre-mapped(and *not* part of the self-learning aspect?). If this is the case, what other factors affect the final A/F at WOT(to cause mine to be a tad lean).

Cheers,Jamie

[deviousKA]

I havent been able to find the formula that the ecu uses after it has calculated a tp, to where final injection pulsewidth is calculated. This would help with full insight on all of the factors.

Acceleration enrichment is an obvious addition if the ecu senses enough tps v/s. It will jump to that routine and add pulsewidth, either by a certain amount of engine cycles or a pre set time. The accel_enrich settings in the rom have something to do with this, they seem to be mapped to a range of TP? These values may be the amount of additional injection, or the engine cycles/time that the enrichment is applied at that TP level?

What im getting at is that perhaps that duration of 14-13.5:1 in your log is also a duration of accel enrichment (of which would be just a tad bit lean).

I have experienced very long durations of accel enrichment needed, very similar to the amount of time before your log drops closer to 12 (accel enrich no longer needed, engine fueling needs stable).

That is with my standalone and ITB anyways.

Btw, I run my wideband in a "test pipe", cat location. Works excellent.

EDIT: Or, it appears as if the accel enrichment may be triggered twice on your run. The lean areas being the ecu jumping back to only the map value. In this case, without good control of the accel enrichment in ecu (needs to be figured out) you would have to richen the points of the map that it is hitting on that wot run.

[slipnfall]

Hmm, interesting. I need to do some more reading on the Nissan ECU's.

Here 'ya go:

[slipnfall]

Paul SAE

[slipnfall]

Both

[slipnfall]

Both SAE

[deviousKA]

Nice sheets, good comparison.

Aside from your a/f seeming to be a half to 3/4 of a point off, those a/f are exactly what the ecu is telling it to do. Maf systems are nice.

Further info on the accel enrich would interesting though.

To convert your DE map data to A/F : 14.7 / (1+(fuelcellvalue) / 128)

for the E : 14.7 / (1+(fuelcellvalue/2) / 128)

[:: orion ::]

does anyone know why there is a dip at 3000 rpm?

Dunno, but it's common:

Stock S14 dyno from "Import Tuner":

Stock S14 dyno from "Sport Compact Car":

???

- Brian