Mass Airflow Readings

[swathdiver]

I'm a bit of an Excel geek, so I feel more at home there using filters, functions, etc to mine the data to spot things. Haha..

When I die, if my family wants to know me or what I did, they'll have to look in excel!

 

[Hi-psi]

The above is a run at the track recorded with a Tech-2 and viewed on TIS2000 software. I also looked at several recorded passes made with the AutoCal on EFILive and no drop while the RPMs were climbing, even with KR.

Thanks for posting that.

Watching the vid, I am seeing some occasional dips by just a few g/sec in your MAF readings as it climbs, which aside from that I seem to be picking up some knock when it's happening on mine, seems similar in behavior.

 

[swathdiver]

Thanks for posting that.

Watching the vid, I am seeing some occasional dips by just a few g/sec in your MAF readings as it climbs, which aside from that I seem to be picking up some knock when it's happening on mine, seems similar in behavior.

You've got better eyes than me then! I saw it dip with each shift as the rpms dropped but didn't catch anything else. I paid particular attention to the graph and gauges on a run made with EFILive and didn't catch that either.

She runnin' good for what she is though and just a few more grams per second than Ken too! LOL

 

[Hi-psi]

Yeah, it isn't very much when it dips on yours, or mine really for that matter. Just maybe 5 or so g/sec for a split second then recovers. Maybe I'm over analyzing things. Who knows. I took another degree of timing out from 4000 up and did another log on the way to work this morning. It actually seemed to be a bit better when I did a WOT pull. There was still some knock, but measurably less than my last log so maybe I'm getting really close on the amount of timing it's going to need pulled in the upper rpm's to be happy. I'm still just a tad rich at WOT too. I'm still seeing that same pattern of the MAF g/sec dipping right before the knock shows up, but again, maybe I'm correlating something (tiny dips) that is normal to chasing my knock issue when there really is no relation.

@kbuskill - Do you happen to know how many degrees total Lew ended up pulling out in the upper RPM's when he did your custom tune? This being my first venture into tweaking an LS based motor, I don't really have a basis into what is a lot or a little amount of timing. I'm up to pulling 6 degrees from 4000 up right now which to me "sounds" like a lot, but maybe it's not that abnormal.

This is from this morning's log during a WOT pull. Again, probably me finding connections that probably aren't there, but it just seems like a pattern.

1. MAF dip, knock up.
2. MAF recovers, knock down.
3. MAF dip, knock up.
4. MAF recovers, knock down.

LOL

 

[kbuskill]

Yeah, it isn't very much when it dips on yours, or mine really for that matter. Just maybe 5 or so g/sec for a split second then recovers. Maybe I'm over analyzing things. Who knows. I took another degree of timing out from 4000 up and did another log on the way to work this morning. It actually seemed to be a bit better when I did a WOT pull. There was still some knock, but measurably less than my last log so maybe I'm getting really close on the amount of timing it's going to need pulled in the upper rpm's to be happy. I'm still just a tad rich at WOT too. I'm still seeing that same pattern of the MAF g/sec dipping right before the knock shows up, but again, maybe I'm correlating something (tiny dips) that is normal to chasing my knock issue when there really is no relation.

@kbuskill - Do you happen to know how many degrees total Lew ended up pulling out in the upper RPM's when he did your custom tune? This being my first venture into tweaking an LS based motor, I don't really have a basis into what is a lot or a little amount of timing. I'm up to pulling 6 degrees from 4000 up right now which to me "sounds" like a lot, but maybe it's not that abnormal.

This is from this morning's log during a WOT pull. Again, probably me finding connections that probably aren't there, but it just seems like a pattern.

1. MAF dip, knock up.
2. MAF recovers, knock down.
3. MAF dip, knock up.
4. MAF recovers, knock down.

LOL

View attachment 214629

I have no idea to be honest. Like I said, the highest I saw the timing advance go on my WOT run was 19°.

The whole time we were tuning he would tell me to find better fuel. I ended up filling exclusively at a Mobil station. Again this was for an 89 tune.
I assume with 93 you could run a little more timing.

He also told me to make sure there was nothing loose and tapping on the engine or exhaust, like a heat shield.

He said the knock sensors are pretty sensitive and will pic up that kinda stuff.

 

[Hi-psi]

He also told me to make sure there was nothing loose and tapping on the engine or exhaust, like a heat shield.

He said the knock sensors are pretty sensitive and will pic up that kinda stuff.

Yes, they will. Essentially they are little microphones. However, you can typically spot false knock fairly easily on the data logs. Real knock (from detonation) is usually progressive. Starts out small, increases. False knock is the opposite usually. Something bangs or clunks, the knock sensor "hears" it, you see all of sudden a big knock number like 6-7 degrees, that then very quickly goes away.

 

[swathdiver]

Yeah, it isn't very much when it dips on yours, or mine really for that matter. Just maybe 5 or so g/sec for a split second then recovers.

Maybe that's just airflow. On my MAFs from the 1980s the air went through a honeycomb to smooth the flow out but this '09 doesn't have that anymore.

I have no idea to be honest. Like I said, the highest I saw the timing advance go on my WOT run was 19°.

On that run of mine posted up there, the timing at WOT was 29 degrees.

 

[kbuskill]

Maybe that's just airflow. On my MAFs from the 1980s the air went through a honeycomb to smooth the flow out but this '09 doesn't have that anymore.



On that run of mine posted up there, the timing at WOT was 29 degrees.

There is also a very distinct possibility that it is just the Torque Pro app not keeping up with real time numbers. I think I will try logging with the Diablo and see what happens.

 

[Hi-psi]

On my most recent WOT logs it modulates between 20-23 degrees of advance @ WOT.

 

[Hi-psi]

Would anyone be willing to data log their Tahoe/Yukon/'Burb/Escalade doing a WOT pull and send me the log in CSV format? Don't really need a lot of data, mainly just three things logged.

RPM
MAF (g/sec)
Knock Retard

Just want to see if I'm chasing a ghost with my MAF theory or actually on to something.