AF really jagged

[kyphur]

I'm using an Autometer Phantom WB hooked up through the AC voltage. You can see where I've overlaid the AC voltage with the my AFR (afr JCP). What I think I'm seeing is the "puffs" between the exhaust gases but I'm not sure. My cam is the LS3 ASA cam (.525/.525 @ .224/[email protected]). The car has the GM crate engine LS3/525hp, Texas Speed 1-7/8th's long tubes with true duals. The WB is on the driver's side in the header's screw in bung. It's supposed to read 1-4v but it gets above that sometimes.

I've tried messing with airflow, injector timing, EOIT settings, etc. Is it just an affect of cam overlap? Maybe a bad O2 sensor?

[kyphur]

anyone?

[kyphur]

Guess not...

[Montecarlodrag]

It acts like a lower scan rate input. Try using EGR or another unused input.
I have a pro interface and have never used those input for wideband so I'm not sure, but it seems like the input you are using has a much lower scan rate, the time step between the valleys and the peaks seems pretty consistent

[kyphur]

Heh, I don't have EGR with an 01 Camaro. Just AIR, and I don't think it outputs any voltage that's readable. From my understanding the only two options for doing it like I have are through the AC or have the Pro interface like you have. Bleh.

[Ben Charles]

You can Log EGR in the tune on a 01-02 computer and its still there in the pinouts on the ECU

[kyphur]

Yeah, I know. Just was tired of messing with harnesses here lately. Plus I'm still moving into a new house so everything is everywhere right now. I don't even have garage doors on my garage.

[jimmyblue]

My wideband has settings for "smoothing", averaging 1 (not at all), 6 or 12
samples (as I recollect). The exhaust stream is "lumpy" to begin with, and there
will always be cylinder-cylinder differences in air and fuel distribution, the
completeness of combustion and so on. You have to look past the trees to see
the forest.

The sample rate of my wideband is also pretty low to begin with (12/sec?) and
the EIO interface polls at 10/sec (20/sec with minimal PID-count) and at idle you
have about 10-15 revolutions, 40-60 exhaust pulses per second. So the meter
is going to way undersample the exhaust stream activity. There's not much
hope of observing anything pulse-by-pulse with the meter I have, where the
sensor hides behind a bunch of control electronics and its own front end
filtering.

A bare narrowband sensor, you can see real pulses on a 'scope, but again
the EIO interface will mask that with its low speed sampling.

So fuggedaboudit.

[kyphur]

Well, it just seems like when I use the AFR error to try and get me in line it also takes into account the high spikes. So if what you're saying is true then I am setting my VE table rich since the spikes are the sampling between the pulses. So it brings the averaged AFR up while the true AFR is lower.

Is there a way to only filter the low pulses through HP Tuners?

[jimmyblue]

There's a lot of crap goes on, and I refuse to trust or use
the paste-histo method because it mixes the crazy and the
transitional with the steady state, which is where you want
your airflow main calibration to come from.

Your wideband may have a smoothing mode which could
help. But there -are- spikes and dips in real life, because
the MAF is a slow instrument, so is the dynamic airflow
somewhat, but abrupt things happen and the PCM is
always a little late. You have to figure out what to
believe and what to ignore, intelligently - not trust
statistics.

[kyphur]

That's how I was originally doing it. I would go through my log manually and adjust in small increments the VE table by hand. It's just here lately that I've started trying to use the AFR error histo for tuning. It actually hasn't been that long at all to be honest. I am getting a FAST dual wideband in a day or so. That'll let me run an o2 sensor in each header bank. We'll see how it goes.