Quote:
Originally Posted by Flr Power
You don't blindly advance ignition timing because you risk unnecessary excessive cylinder combustion pressure past MBT...
|
Quote:
Originally Posted by parmas
Agreed. But What if you don't have access of a dyno or knock control system, how would you tune for w.i?
|
Hey gents. Thanks for the feedback. Appreciate the dialog. Bunch of assumptions being made with the above, though.
First of all and despite my original post, I was only a noob with WI, not tuning or FI per-se. And that label is rapidly wearing off at this point anyway.
Timing is not being advanced past MBT. That is an adjustable parameter as well - I just failed to mention it. When you advance, you adjust them both by the same amount.
My settings are really:
I can go up to 10 degrees of advance or retard:
WOT MBT SPARK 1-3.8krpm +8*
WOT MBT SPARK 4-4.8krpm +6*
WOT MBT SPARK 5-7krpm +8*
WOT SPARK 1-3.8krpm +8*
WOT SPARK 4-4.8krpm +6*
WOT SPARK 5-7krpm +8*
The settings were not blindly changed at all. Not sure how you got that impression. The motor was well tuned before I started spraying with the HFS4 and we are talking about a stock motor with an aftermarket supercharger here. The MBT is determined by the PCM based on the given conditions. WOT MBT had to be lowered already to start with when the blower was installed by retarding the ignition timing (hard coded in the tune supplied by the Supercharger vendor). What I see myself as doing here is uninstalling the spark retard more so than just randomly cranking up the ignition timing by loosening a bolt and then twisting the distributor some arbitrary amount by hand to make power.
I was actively logging the appropriate PIDs as well as monitoring them real time to see what the motor was doing. I could see if and when the PCM was pulling timing. WBO2 is monitored as well. I was most concerned with Long Term Spark Retard and backed off the spark advance in the appropriate RPM range when any hint of it is registered. The PCM adjusts in half degree increments. If we were in the danger zone, this reading would be going crazy - meaning that the PCM is going crazy by pulling the timing in response to the crazy knock.
Advancing the WOT & WOT/MBT timing in 2 degree increments is also far from blind. That was the approach I took with the assumption that I would probably stop at 7-8 degrees of advance. I have read enough about WI/WMI to see that folks tend to get 6 to 10 degrees of ignition advance over not having it so used that as my ceiling - along with the device's limit of 10 degrees of advance or retard over the loaded tune.
Bottom line is that I tuned the WOT spark advance with a target of 2-3 degrees of short term retard under extreme conditions and absolutely zero long term retard under all conditions. And like I mentioned, I eased into those settings. The other tack I took was to ease into the higher RPMs and boost levels as well.
In fact, I now keep the tuner device on all of the time now with the following 4 soft gauges loaded (I'll try to post a pic later):
ST SPK RETARD degrees
LT SPK RETARD degrees
AFR/WBO2 Percent (via analog input)
WMI CCs (estimated - via analog input)
I am also monitoring MAP and BARO on another gauge page - among other things.
Until now, I was not considering an EGT sensor and controller but now that I am I am in this deep, it does seem like another great (off-dyno) tuning tool.
With the tools that I have available, I feel that I do not really need a dyno to come
close to ideal. That is not to say that an experienced tuner could not extract even more HP on a dyno because I believe that they can. it is just a question of how much more.