Need help tuning my supercharged 94 Z28!

[gmcknny1]

Nope, but I will, thanks.

[gmcknny1]

Heres todays datalog using EEHack. If anybody can figure out what changes I need to make I will also add my bin file. Or just use the EEX.XDF file. Also should I use the Lock BLM patch and the Stoich AFR target under funtions?

[gmcknny1]

Can anybody take a look at my data log and tell me if I should make any changes? Thanks

[newellshk]

I would have looked sooner but I hadn't used EEHack before. The software is much nicer than I expected.

First of all the log looks like a major improvement!

One of the first things I noticed is how the left bank BLM goes all the way to 153 after it enters closed loop, while the right bank stays quite close to 128. I'm not sure if that can be a result of your setup or if it's indicating that you need your injectors cleaned.

Next I can see that the idle rpm still drops too low when you initially put it into drive, then it mostly recovers as IAC steps increase. I looked in the XDF to see if there is any kind of in gear adder and I don't see any. Maybe the operating system doesn't support that, or maybe it just hasn't been put into the xdf.

Your idle rpm seems a bit low also. I downloaded the stock 95 z28 bin and the target idle speed is 800 in gear or P/N with a warm engine. You might try to duplicate that and see if it gives you a more stable idle.

[gmcknny1]

Do I keep making idle adjustments using my throttle stop screw or can I make changes to my tune via one of the tables listed?

[newellshk]

Adjust the desired idle speed using the "* Idle Speed Target RPM" table under the "Idle Air Control (IAC)" category. Your throttle stop is probably okay if not a touch too open. The IAC counts got down around 30 which is a bit lower than Terminal_Crazy suggested. I think the only potential "problem" would be if you were at a lower elevation with dense cool air the IAC could theoretically "lose control" if the IAC counts hit 0. In reality though the ECU can still control the idle speed by adjusting the spark timing. Notice that when the idle speed is hovering around the Target RPM the computer is constantly adjusting timing without changing IAC counts. Only when the idle is too high or low for a longer period does it adjust the IAC valve. Since you seem to be close to sea level judging by the Baro showing 99kpa you probably won't have any problems with your current throttle stop setting.

I think that some stock calibrations for automatic transmissions have the P/N idle speed set a bit higher than the in gear idle speed. Doing that will likely help with a smooth transition when putting the trans in gear. Maybe try 800 P/N -> 700 in gear and play around with it until you like it.

[steveo]

eehack can test idle parameters in real-time. simply use eehack's 'control' section.

check idle 'override' and spark 'enable', then play with the idle speed and timing until it feels right. it will default to your existing target and timing.

you may want to do this in neutral too. and while warming up. experiment a bit at different temperatures.

you can get test a hotter idle by overriding both fans to 'off' while monitoring coolant temperature, so you don't have to wait until you are in traffic in the baking sun to figure out that your idle only works in your driveway.

if you check the 'steps' button, you can control the IAC motor directly (so the ecm isnt trying to hit an idle target), you can use this to experiment and see how it behaves in other cases.

there's a small clipboard button next to the idle and timing controls, if you click them, it'll copy those parameters to the 'notes' screen in eehack so you don't have to write them down. then use those settings as hints for new values to use in your bin.

edit: one more thing, the LT1 really likes its throttle plates nearly closed so it can use the idle passages. the passages are fed both by a bypass hole and the IAC valve. the passages run through the manifold and feed the rear and front of the plenum more uniformly than the throttle plates. every lt1 i've tuned tends to idle best if nearly all of the idle air comes through those passages. if you have to open your throttle plates to get good IAC counts, in my opinion it might be time to consider drilling out your throttle body's idle air bypass hole a bit.