The ULTIMATE GUIDE to Idle Tuning! (For ECU Upgrades & Engine Swaps)

This video can apply to all sorts of cars so share it with your friend who's got a sick swap that won't idle right! See below for more notes about this video.
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Extra Video Notes:

0) Yes, step zero. MAKE SURE you don't have any vacuum leaks before tuning idle.

1) PID values in the idle settings could have a video of their own, the coverage was very brief here. See tuning manuals for more information.

2) An alternative to unplugging the ISCV valve during idle screw setting is to lower idle to 0% duty in the tuning software.

3) In the MEITE idle settings there's something called "PID Deadband" that can be very useful. If you're using closed loop, and have issue with idle hunting but only by 50-100RPM, try increasing the Deadband to a larger value. This is the amount of error (Target RPM vs Actual RPM) that's allowed by the ECU where it will not attempt to chase the target. So if your target is 850RPM, and your engine is idling at 900RPM, with a Deadband setting of 50RPM, it will not attempt to chase it down to 850.

4) Pertaining to AFR affecting idle: A very common upgrade is larger fuel injectors for boosted applications. The stock ECU can handle about 15% larger injectors, which is around 300cc or maybe slightly larger. Above that (RX7, RX8 injectors or bigger) you need a standalone. But when you upgrade injectors on a standalone you need to input the correct settings for those injectors, rather than just subtracting fuel from the maps and tables. The 2 main settings are injector size and dead time. Dead time should be provided when you buy aftermarket injectors like Injector Dynamics, Deatchwerks, etc. For OE injectors like RX8 you can calculate it (https://www.miataturbo.net/ecus-tunin...) or if you need to guess you can just use a value like 1.00 and it should be close enough. It's best to get it accurate. Keep in mind your entire fuel tune will be thrown off when you change dead time. (In MEITE: Go to the search box and type "dead time". In Tuner Studio: Fuel Settings - Injector Dead Time). You also need to change the injector size which will also throw off the entire tune, so do that as soon as you install the injectors. (In MEITE: Under "START" Menu in the Injection Driver box, adjust "Pri. Inj Size". In Tuner Studio: Basic/Load Settings - Click "Calculate Required Fuel" and input your data, this will repopulate the Required Fuel value. Double injector size = half the required fuel value.)

5) If you have a 1990-1993 (1.6L) Federal car, or 1990-1992 California car, it runs what's called batch fuel injection. This is where #1/3 and #2/4 fuel injectors fire simultaneously. You may notice, especially with larger injectors, that idle AFR needs to be in the 13's to be stable, this is normal. Alternatively, you can add 2 wires between your fuel rail and ECU to set up sequential injection. You need 1 signal wire per injector to do this (Early cars had 1 signal per 2 injectors.)

6) There is a lot that goes into this simple seeming topic. It can be harder even than cruise tuning or WOT tuning at times. If you guys have any pro tips you've learned from experience, drop them in the comments!
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Additional Info:
ME221/442 Tuning Manual: https://motorsport-electronics.co.uk/...
ME221/442 Base Maps: https://motorsport-electronics.co.uk/...
Megasquirt Tuning Manuals: https://www.msextra.com/manuals/
MS2 Base Maps: http://www.megasquirtpnp.com/mspnp2_m...
MS3 Base Maps: http://www.megasquirtpnp.com/mspnpp_m...
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0:00 Intro
0:51 Idle Components
6:27 Base Idle Setting (Stock & Standalone)
10:43 Open vs. Closed Loop Modes
16:30 What Variables Can Affect Idle?
18:59 What If The Car Won't Idle At All?
23:29 Idle Dipping / Stalling
26:26 Spark Scatter / Idle Advance
31:13 Pro Tip & Additional Idle Settings
34:29 Setting Up A/C & Fans
39:18 Outro