I had my car running pretty decently with 3.044 before, as can be seen in the V6 version. After upgrading the FW to 3.047 for some reason I couldn’t get it to idle as nicely as before.
I’ve played with airflow and ignition PID, correcting the VE, airflow, and all other related Idle settings. But I feel like I’m missing something.
If anyone could share their opinion/advice that would be greatly appreciated
Where in the log are you referring to? Idle config and log looks pretty smooth in the middle… but then you have PPS signal introduced and RPMs are all over the place?
There are many many changes in both your configurations.
It is not possible to keep stable Idle rpm when the lambda fluctuates as in your log.
If you fine tune the VE table in idle region (to have as flat lambda as possible in the rpm range 800-1200) gives you stable idle. Also revert idle PID (ignition and airflow) settings to the values for V6 base map.
I already tried going back to the V6 settings, that didn’t change anything, also the idle used to be quite smooth at lambda 1, but now to not have it stutter it needs a richer mixture (around 0.8).
When I let the car idle after driving it hovers around 0.8 lambda, but after shutting it down and starting about 10 minutes later, it is hovering around 1.1 to 1.3 lambda, without changing any settings.
Any tips to perfect the VE table, and how to circumvent the idle lean condition after hot start?
Thanks
The most important thing that many people is missing is the fact that PID is not to cancel oscilation. If there are oscilations PIDs make it worse.
So first disable all PIDs for idle (set it to 0) and then work with Airflow DC in different temperature.
Select different targets and make sure the RPM are as near the target as possible and do not oscilate. In such situation the oscilation is caused by wrong lambda (floating). If you have sport cams it is hard to set smooth idle.
Then work on VE table to get stable lambda.
Your problem sounds like a heat soak of IAT sensor. Use charge temp table to solve it.
However it could be connected to any active fuel correction.
I’ll have a go with no PID and trying to get the correct VE table.
However the charge temp correction doesn’t work the way it needs to.
When I get off the highway for example it idles around the lambda target, but when shutting the car off and 5 minutes later back on, it is running lean.
So using the charge temp correction it will run rich during normal operation just to compensate for heat soak of letting it sit for a couple minutes.
Give this table a try as it is designed to prevent the heatsoak.
For low air flow (idle) the charge temp is more like CLT than IAT.
When you drive on the highway the engine airflow is much higher so the charge temperature is more like the IAT. Of course a lot depends on the intake manifold design (eg. plastic vs aluminium), sensor design and sensor location.
What I mean specifically is when I ‘arrive at my destination’, the car has been driving so the heat soak is much less (so there is no need for charge correction), but after letting the car sit with the engine off, there is heat soak, so the charge correction now is needed.
After starting, the car idles lean, but after driving, then is running normal, since there has been more airflow through the system.
I have already implemented this before in V2 software as well, but it’s either overcompensating during normal driving, or not compensating after a hot start.
There’s probably another factor at play here that a lot of people ignore: fuel temperature.
After the fuel in the rail heatsoaks from sitting in a hot engine bay, with no fuel flow (engine off or very low load), it’s very easy for the fuel to hit over 60c in some instances, and significantly contribute to a lean condition.
A custom correction for fuel temperature is probably the most straightforward way to solve this, but with a well tuned VE table, after start enrichment at high coolant temperatures, and short term trim/closed loop fueling that can come in as after start enrichment ends, it’s also possible for it to work well enough.
