Signs of excessive backpressure?

[Crazycanadian]

Well update.. I have changed the ignition coil packs and SO FAR I have not had any hesitations. I am glad to say the problem, form now, is fixed.

Now an off topic question, does anyone understand the logic behind how the stock ECU controls ignition timing during idle? I see on VersaTuner the idle ignition adjustments table, but they don't apply at idle as they do in the table, at least from what I have seen.

So far from what I can tell the car when it is idling will start with 10* of ignition timing. Then it will reference the ignition adjustments table as a + or -. So if the table has 5, it will do 10* + 5* resulting in 17*. Where does it get this base number of 10*, because it most certainly is not from the ignition maps.

Now the reason I am asking this is something people do, common on standalone ECUs, is they fluctuate ignition timing at idle to generate a cam sound. I know I know, you may hate it or you may love it, but besides the point I was wondering if there was anyway to achieve this on our stock ECU? And yes, I have tried changing the ignition adjustments table and it did not work. I did anything above idle target RPM it -30* to force it to drop and then anything on target or below target will be 10* to get it to jump up, but the car does not do this and it manages to find a way to idle steady.

I attached a video of someone who is on a standalone ECU and achieved this sound.

When you changed the ignition idle adjustment tables, how did you changed them?? Those tables work the same as closed loop idle stability tables in a stand alone ECU..

If your target is 800 and the car is at 850 it'll pull up to 8 deg out.. Try reversing from whats in the tables from 150 down to 0 and from 0 to -150... If the ECU is trying to command the idle up using positive numbers, but you've got negative numbers, in theory is should continue to push the idle down and vice versa. You'll want some kind of catch point in that table to keep it from stalling.

this likely wont work as well as you'd like though. The ECU will also use the throttle body to help control idle.

 

[brandon19]

I started by zeroing the adjustment tables to see if that made a change and it did, which was 10* of timing, so I assume this is the base idle timing. During this to adjust idle it was using relative throttle position to achieve the idle target, hence when trying to achieve the "cam" sound the throttle was adjusting to a point where it was open enough that it could idle at low timing. If I was able to force the throttle to a certain position then it would be easier to achieve, otherwise it won't be possible.

There will be a base throttle position table and corrections somewhere in the ECU for the throttle which are not exposed with VT and probably never will sadly.

 

[brandon19]

This is off topic but I might as well ask. I'm going to be going port injection very soon but plan to stay on pump gas 98 due to e85 being unaffordable to use as a daily where I am. What power / boost levels would you expect (within reason) being on 98 octane, or if it is even worth trying to push for more. Is 500hp doable or even reliable, maybe 550hp? I already imagine running richer AFRs will help to some extent and trying to raise power near redline, rather than increasing the peak torque range.