Hi everyone,
I need your help. I’m completely stuck.
The issue concerns my Audi 100 C3 with the 2.3 NF engine.
I installed the Invent Jetronic system (firmware 4.1.6) and got it up and running. I initially started with batch injection , so without modifying the distributor. The initial startup went okay. Then I performed the adaptation drive, exactly as described in the manual. The result: a fluctuating idle. I thought, "Okay, maybe this is due to the batch injection." So, I modified the ignition distributor and, following the manual, shortened the trigger vane by 1.1 mm. A fresh start: basic setup, adaptation drive. But unfortunately, the same problem persisted.
When I disable the lambda control, I can achieve a reasonably stable idle. The only exception is when the cooling fan kicks in; at that point, the RPM drops slightly.
As soon as I enable the lambda control, the RPM fluctuates wildly between 500 and 1500. This happens even after completing the adaptation drive and fine-tuning the mixture enrichment settings for both load and idle conditions. The log clearly shows that with every change in the lambda voltage, the RPM rises or falls accordingly. Everything runs fine during normal driving; the issue is strictly limited to the idle.
I also experimented with the MAF emulator table, thinking the problem might stem from the ignition timing advance. However, that didn't help much—nor did making adjustments to the PID controller settings.
I really need some assistance here. I’m at a complete loss as to what to do next.
Oh, one more thing: the idle control valve is functioning correctly, and at first glance, I can't spot any vacuum leaks. The lambda sensor isn't very old, either.
Attached is the log file from my most recent adaptation drive. I made some mixture adjustments during this run. Towards the end of the log, I disabled the lambda control and reset the mixture adjustments; you can see that the idle subsequently stabilizes. I hope you guys can make some sense of the data in there.
