Evo X Idle - Built Motor

I am having a hard time determining if I have a calibration issue or a mechanical issue. I have done several Evo calibrations on stock motors, and this is my first built motor. This one is on my personal vehicle so I have plenty of time to test. Stock ECU using Ecuflash.

The car will not idle well. It seems to try to idle at about 200 - 500 rpm consistently until it dies. Otherwise, it drives just fine. I've tracked down and fixed vacuum leaks, tried adjusting fueling, adjusting target idle rpm, mivec seems to track properly, maf seems good/swapped with known good maf, fuel pressure holds steady. At this point, I don't know if I should be adjusting with more tables or looking for a mechanical issue.

The things changed since the last calibration that may or may not affect idle:

Gsc s2 cams/valves/beehive springs

9.5:1 CR

ID1300 Injectors

I can post any other info I need to. Thanks in advance!

Hi. Three things about idle on Evo X.

1) You need to make sure the throttle body is cleaned. Disconnect MAF before cleaning and plug it back in after cleaning. Also you can disconnect battery for cleaning.

2) After cleaning throttle body you need to let ECU learn how to idle by starting the enging up and letting it to warm up to the proper temperature, then shut it down for 10 seconds, then start it up again and let it idle for at least 10 minutes without any electrical devices being turned on ( AC, music, light etc). After that you can take a short trip and drive it in start/stop mode. Once done- you should be fine.

3) Fuel injectors of that size are very difficult to control at very short pulse widths. That might ba a contributing factor to unstable idle too.

By the way - are you sure S2 cams are set properly?

Ok I'll try cleaning the throttle body and doing the idle relearn procedure and post the results.

If I continue to have issues I'll look back into the cams and consider any additional adjustments I need to make with the injectors.

Thanks

I've not had an issue with ID1300 unless an engine didn't have a proper filter and they got debris in them, so I have a hunch your idle throttle airflow table isn't dialed in yet. The ECU will only learn so far, and any time you can set base values close to what's needed, the better and smoother the engine will run. Try adding some throttle angle in the table, monitor how much angle the ECU actually uses to stay on target, and continue adjusting accordingly.

Also make sure fueling at idle is on target, because a lean engine may struggle to maintain idle.

I did adjust the throttle airflow table a bit, but now that I think of it I think I returned it to stock scaling after it idled extremely high... But I fixed a vacuum leak since then. I'll revisit that table, thank you.

Have you found that GS S2 need very much adjustment in that table? Since they're not wildly aggressive I didn't want to go too crazy and assumed they should probably be fine at stock or close to stock scaling. My only other experience was with kelford 214b and they didn't seem to need any adjustment to idle nicely.

The ECU will learn a decent amount, but I always prefer to adjust the settings so the learning doesn't have to do much.

That way you get right on target with minimal delay or wandering. It might learn far enough to idle without adjustment, but proper adjustment will only help.

The issue is that it's not that easy to set up proper idle in Evo X as there are about 10 different tables related to idle. If you aren't familiar with all those tables it's better off just to let ECU to learn the new conditions - it would be much quicker and easier and it helps in 90 percent of the cases.