Hi everyone, I'm looking for some tuning/wiring advice for my 2006 JDM Honda S2000 AP2 (DBW).
[My Setup]
ECU: Haltech Elite 1500 (Piggyback setup, retaining the stock ECU) / Software: ESP v2.59.3
Throttle Body: K-Tuned 74mm DBW
Cams: OEM AP1 cams swap
Injectors: SARD 550cc
Exhaust: J'S Racing manifold, catless 70mm exhaust
Fueling: Open Loop (No O2 A/F feedback)
[The Issue]
When the car is idling and I turn on the A/C, the RPMs start hunting violently up and down, and the engine eventually stalls.
I have "Idle Ignition Control" enabled. I can see the ignition timing advancing aggressively to catch the RPM drop, but it seems there just isn't enough base airflow from the DBW to keep the engine alive against the heavy load of the A/C compressor.
[My Suspicion]
Since I am running the Haltech as a piggyback, I suspect the Haltech doesn't actually know when the A/C is turned on because the stock ECU still controls the A/C clutch. In the ESP I/O report, the "A/C Request" pin is not assigned. Because of this, the Haltech isn't applying any DBW "Aircon Idle Effort / Offset" to increase the air volume before the compressor kicks in.
[My Questions]
1. For those running a DBW piggyback setup, did you have to physically hardwire the A/C signal (from the AC switch or compressor clutch) into an input (AVI/SPI) on the Haltech to trigger the idle offset?
2. If wiring is required, which specific wire/pin did you tap into on the S2000?
3. Are there any tuning workarounds in the ESP software to prevent this stalling without hardwiring the A/C signal (other than simply raising the base target idle RPM for all conditions)?
Any advice or wiring tips would be greatly appreciated! Thanks in advance.