Pop quiz

[SSpdDmon]

Who can identify why timing all of the sudden drops off during my WOT runs?

It took me a second....but, I figured it out. Thought I'd share incase anyone else runs into this. Wanted to give you guys the opportunity to chime in before I just gave it away. ;)

Log shows OLSD, WOT runs (well, >75% TPS). Other than idle control, the only timing modifications were done to the base and high/low timing tables.

[gto_in_nc]

Do you have a transition in {B5910} at approximately 190*F? My stock table stepped down at 80*C, which is not far South from there. (Based on your MAP, RPM and TP%, however, I'm guessing you are nowhere close to the 0.16 to 0.44 g/cyl CYLDYNAIR_DMA numbers where I'm seeing possibility...)

EDIT: On second glance, my stock IAT table ({B5911}) takes a small step down just North of you. Not sure what your tables look like but are you in an event-rich environment?

[SSpdDmon]

Nope...B5910 is all zeros from 122*F on up at WOT.

IAT modifier is also all zeros up to 104*F at WOT too.

Good idea...but, not the culprit here. :)

[joecar]

Hmmm... the only clue is that MAP fluctuates a little...

[TAQuickness]

The first dip was the flux capacitor warming up, the second was when you hit 88 mph, and the third was you arriving in 1955.

You can avoid the spark dips by upgrading you altenator to a Mr. Fusion,

[WiseGuyZ06]

The first dip was the flux capacitor warming up, the second was when you hit 88 mph, and the third was you arriving in 1955.

You can avoid the spark dips by upgrading you altenator to a Mr. Fusion,


and by fueling it with beer..... sweet movie..all time favorite:rockon:

[SSpdDmon]

Hmmm... the only clue is that MAP fluctuates a little...

You're right...I didn't realize I left out the grams/cyl .pid that would have given you the only other clue. That's my bad...


The first dip was the flux capacitor warming up, the second was when you hit 88 mph, and the third was you arriving in 1955.

You can avoid the spark dips by upgrading you altenator to a Mr. Fusion,

Dude, if I could travel back in time, I'd make some wise investments in my name and I'd be taking care of my Jay Leno like car collection. :lol:

[SSpdDmon]

Alright...so the answer was burst knock retard. It was still on the stock delta airmass settings. The slight changes in the grams/cyl. (only .01~.02 from what I remember in the log) were just enough to allow the PCM to pull the timing. So, if you plan on keeping BKR active (like me), you might want to increase the stock thresholds slightly so they're .04~.06 grams/cyl. instead of the stock .02~.04 settings.

[TAQuickness]

That was my first answer.

Note to self, always go with the first answer....

[SSpdDmon]

Speaking of jiggawatts, you need to fix your sig. It's 1.21 man...get it right! ;) :lol:

[gto_in_nc]

Dang! Ya know, I actually thought about that but thought the pressure looked pretty steady. Didn't even think to check to see how sensitive BKR is. (Now you've got me thinking about my own burst knock retard...)

[SSpdDmon]

Dang! Ya know, I actually thought about that but thought the pressure looked pretty steady. Didn't even think to check to see how sensitive BKR is. (Now you've got me thinking about my own burst knock retard...)
mission accomplished :)

[gto_in_nc]

Alright...so the answer was burst knock retard. It was still on the stock delta airmass settings. The slight changes in the grams/cyl. (only .01~.02 from what I remember in the log) were just enough to allow the PCM to pull the timing. So, if you plan on keeping BKR active (like me), you might want to increase the stock thresholds slightly so they're .04~.06 grams/cyl. instead of the stock .02~.04 settings.

Hmmm...

My {B5954} has 0.014893 grams from 800 RPM up.

[SSpdDmon]

Hmmm...

My {B5954} has 0.014893 grams from 800 RPM up.

I'd probably double or even tripple that. (Don't have B5954 in my tune (mine's B6210) - assuming that's your Delta Air Mass table though.)

[gto_in_nc]

Exactly. Delta Air Mass. I think I'll triple it! I suspect this may the answer to my (unasked) "where the fcsk did my timing go?" question. Small variations between what I think I should see and what I really see, timing-wise (after accounting for KR, IAT, ECT, etc.)

[joecar]

Jeff, post your new delta airmass table. :)

[SSpdDmon]

Simple....it's .04grams/cyl. across the board. :)

For mine, that equates to 2x the stock table from about 1600rpm on up. As for the other burst knock settings, I have the duration set to 60 (vs. the stock 3 crank revolutions) and the decay rate set to .125 (1/2 the stock .25). So now, when I mat it, I don't have any burst knock and I'm up to full commanded timing within 0.1~0.2 seconds.

Relying on actual KR (i.e. burst knock disabled), if knock actually occurs, it takes longer (lower recovery rate) for timing to return to commanded. That's why I believe burst knock is a good, preventative feature to have. :)

[gto_in_nc]

OK, so... A question:

Why the wiggle in MAP? I can't see the green TP% trace at all on my laptop so I'm assuming it is pegged at 100%. If so, why are you seeing multiple mid-gear WOT pressure fluctuations? Someone teach me! :D


BTW, the changes to Delta Air Mass (I ramped up to 0.03 at mid-RPMs and .05 up top) combined with a rethink and ramp-out of IAT vs. RPM has now got my spark behaving in a fashion that not only makes sense (thanks to my learning on the forum) but does what I think want! Of course, what I think I want changes often... :D

I left both IAT & BKR more sensitve at lower engine speeds thinking this should contribute to a smooth drivability (sounds like I'm describing a beer!) I numbed BKR up higher to keep it from being hasty to pull advance when I poke the pedal. I decreased the importance of IAT as RPMs increase because I have a sensor heatsoak problem. I need to pick mistermike's brain because I know he's addressed it with his '04 GTO - basically, the thermocouple reads the temperature of the plastic surrounding it rather than air flowing past it. I want to correct that and then revisit IAT vs RPM.

So what's next? :beer:

[dfe1]

.

So what's next? :beer:

Move to New Jersey, become a clerk typist and .....

[joecar]

Move to New Jersey, become a clerk typist and ........ROFLMAO... :muahaha::muahaha::muahaha::muahaha::muahaha: