Idle questions

[blue_falcon]

The help files aren't much help to me. I need someone to explain what some of these things do. If I add to this what effect will it have

[txhorns281]

yeh some of this stuff is pretty complicated to me too, but I guess a good starting point would be to address particular issues with your idle. From there you can at least learn about what will improve your condition. That way you discuss the theory, and actually get to go test it on the road! So what are your specific problems?

[blue_falcon]

I've just been having trouble getting a smooth idle, I haven't been able to drive the car due to a bad tranny, which is fixed and going back in tonight or tomorrow. I've drilled out the TB 1/32" and moved the TB set screw a little bit. I also did all of the things with VE, IAC and Idle speed that I was supposed to. Who knows maybe I went too far with the VE

[MNR-0]

I recently discovered my O2 sensors were not properly calibrated - changed by some ancestor tune nearly a year ago. No wonder I couldn't get my trims and idle purrrrfect. Simple mods to the Airflow Mode Gain tables and now I have properly oscillating O2s and MUCH improved fuel economy. I mean, I was getting 9.7l/100kms before, but NOW its like 7.4l/100kms freeway cruising.

So, before idle tuning check your O2 sensors are maintaining closed loop effectively. Otherwise, fuel hunting will ensue.

[txhorns281]

Well at least for me, even if my O2s are configured properly, my motor setup and modifications (mainly the cam) sends mixed signals and "false" samples to the O2s which screws lots of things up! > Screws even the wideband up...

[WS6snake-eater]

I recently discovered my O2 sensors were not properly calibrated - changed by some ancestor tune nearly a year ago. No wonder I couldn't get my trims and idle purrrrfect. Simple mods to the Airflow Mode Gain tables and now I have properly oscillating O2s and MUCH improved fuel economy. I mean, I was getting 9.7l/100kms before, but NOW its like 7.4l/100kms freeway cruising.

So, before idle tuning check your O2 sensors are maintaining closed loop effectively. Otherwise, fuel hunting will ensue.

Care to post what your AMG tables look like???

[MNR-0]

Ill post em when I get home. Can FTP out of the Office network.

My O2 Error tables are stock. Since they are a multiplier of the Base Airflow I found it easier just to modify that. If the idle O2 sensors are lazy, multiply the Base AIdle Airflow Mode by 2 from cells 1 upwards.

If the sensors are railing when moving, modify the overall Base Ariflow Mode from cells 36-80 down 2 points. 36-80 corresponds to 36-80 g/sec of Mass Airflow, where you do most of your part throttle driving.

Now if you have oscillating O2 sensros at idle and you still get hunting, try reducing the fuel shot overshoot by reducing the Base Idle Airflow Mode from cells 1 upwards.

CAMS typically have large inlet durations and due to reversion at idle will discharge gobs unburnt fuel through the exhaust port. This discharge of rich mixture forces by the O2 sensors to swing to lean, often overshooting the R/L switchpoint. The car begins to hunt for a rich condition again overshooting the switchpoint.

The trick here is finding the watermark where this occurs and setting your idle just above it. Increasing idle RPM is the easiest way to generate even exhaust pulses so as not to cause hunting.

[blue_falcon]

I've got my idle at nearly 950, I don't want to be that high let alone any higher

[WS6snake-eater]

TTT still hoping to get a peek at those o2 tables.

[AnotherUser]

One of the HPTuners guys posted somewhere that O2s will be a little lazy at idle.