Apex'i Neo Karmen airflow problems.

[steve]

Airflow Signal Output Problems with the AFC Neo

Copied from the 3Si forums since it applies to DSM's as well.

Executive Summary:
After analyzing the data I gathered from my AFC Neo and testing another Neo on a testbench, Apex has confirmed this week that there is a problem with the Karman (frequency-based) airflow correction feature on current-generation (firmware revision v1.103 or less) AFC Neo products. As shown in my logs, the AFC’s output is incorrect and erratic under certain conditions, most notably when the input airflow signal rises above 1000Hz. The problem does not seem to be limited to anything specific to the 3000GT/Stealth platform, and likely applies to any application using the Karman feature.

As you can see from my logs, the output airflow is wildly inaccurate at times, and I do not recommend that anyone use the Karman feature of the AFC Neo until Apex releases a fix. For me, one temporary solution seems to be to keep the airflow signal under 1000Hz, as the car seems to be have normally under those conditions. The solution I’m currently using (so that I can run 450cc injectors safely) is to decrease my base fuel pressure from 43psi to 33psi; that lowers the injector output enough that the OEM ECU can compensate for the extra fuel. Then, I can either turn off the correction on the AFC Neo or I can return the ECU wiring back to stock. This allows me to drive the car without having to swap my OEM fuel injectors back into the car.

Apex is working on a fix now, and I’m hoping to be able to test a revised version within the next week or two(i.e. before the end of May). Hopefully, the fix will be a simple reflash of the firmware that can be applied to all existing AFC Neos. Much to their credit Apex has (save an initial delay in confirming the problem) been very responsive and seems to be trying to do the right thing. I will post an update to the web page above (and this thread) when I’ve received the revised version. If you have an AFC Neo, check back on this thread or my website for updates -- as of now, I think I should have something to report by the end of May.

I don't own a Neo to confirm this report but the OP is very qualified as you can tell from reading the link.
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