Hi all,
I'm hoping to get some advice on my tuning. Here's my numbers from Turbolink:
BLM: 128
LV8: 255
ESC Counts: ~9
IAC: 108 / 42%
Retard: @2-3 at launch / max 3.8 in 3rd
O2 Counts: 8-20 at launch / 0 during run
O2 mV: 757-824
TPS V: 2.5-3.68
1. My Caspers knock gauge is lighting up like a christmas tree, but TLink doesn't show much detonation. Which should I believe? Since TLink only gets 1 frame of data every 1.25 sec., there is a lot that I could be missing with TLink.
2. Why doesn't the knock gauge and TLink agree on the severity of detonation (getting red lights on gauge)? Is the gauge too sensitive?
3. I'm at about 17 lbs. of boost now on pump gas. Am I maxed out with the pump gas?
4. My TPS voltage and IAC is low. How can I bring it up? Can I get more power by increasing TPS voltage (I'm getting full boost already)? Will more detonation result?
My mods are a Thrasher 92 chip, AFPR (45 psi vac off), ATR w/o cat, cold air intake, hot wired Walbro 307, 160 thermostat, stock everything else.
Sean
87 GN
1. The Knock gauge is on the EST *into* the ECM. TurboLink is reading what the ECM *did* with that input. Hence, the output is filtered by the ECM and acted on before being reported. The 1.25 second frame rate doesn't really come into play, since the the ESC counts tell you approx. how much (timewise) knock occurred since the last sample. The longer the knock event was, the higher the *change* in the ESC count.
The ESC count is actually a "block" of counts (i.e. ESCcnt = number of clock cycles during the knock event/256).. so it takes 256 counts before it reports one "ESC count".
2. They probably agree (although calibration could be a factor with the gauge). Look at the ESC counts change between frames...
3. Depends on the chip, timing, fuel quality, air density, temperature, A/F ratio, etc. However, in my experience, that's about right with 92 octane at 1400 ft altitude. The Thrasher may have lower timing, so you might be able to squeeze a pound or two more boost with a little more fuel.
4. TPS voltage needs to be adjusted (see the Maintenance section of the web page from the pull down menus at the top of the page... detailed instruction on both TPS and IAC).
A couple observations:
- O2 sensor looks good ... 0 during the run is expected, since the car is in power enrichment
- O2s during the run? Did they "fall off" or were they steady? Rising?
- ESC counts don't mean much unless we can see them over time
- BLM is locked at 128 because at idle, the Thrasher chip is Open Loop and at WOT, most chip burners lock the BLM at 128 to prevent the ECM from "learning" at WOT.
So if the knock gauge is "farther upstream" than the T-Link data, am I really beating the hell out of my internals by getting massive detonation (according to the red lights on the gauge), even though T-link is not reporting major spark retard? The O2 voltage seems to alternate between increasing and decreasing values during some runs and slowly decreases versus others, but the values always seem to stay within the "safe" limits.
Not really ... the guage is seeing "preprocessed" input. The ECM sees the same thing, and via some pretty sophisticated inputs OTHER than ESC, it decides if the EST is reporting knock, valvetrain noise, something rattling (i.e. downpipe), etc, etc. It then either pulls timing out (knock retard), ignores it, feeds more timing in, etc.
So what you are seeing in the data stream is probably more indicative of what the ECM thinks is "abuse". The knock gauge is a great tool for getting an early warning, but you need to correlate it to what the car is doing with it.
Thanks Ken, I probably could have answered my own question by reading the T-Link owners manual in a little more depth.
It seems like my knock gauge may a little too sensitive then because I'm hitting red lights with only 3.8 degrees max retard and acceptable O2s. The only mods under hood are a cold air intake and AFPR, so I don't know what noises could be causing all this false knock. Does anyone else out there have a similar issue with their knock gauge?
Thanks,
Sean
87 GN Cold Air Intake, ATR, AFPR, HW Walbro 307, ROH, Bilsteins, Eibachs
98 Vette just purchased - stock for now...
Might be worth it to talk to John Spina ... there might be a "calibration" step that you can take. John's REALLY sharp with this type of stuff and might have some good input.