Idle Control Advice

[MarkMc]

Some information for everyone.

First thing that must be burnt into your brain. IDLE CONTROL IS NOT A FUNCTION DESIGNED TO SMOOTH OUT A ROUGH IDLE. IF THE ENGINE DOES NOT IDLE SMOOTHLY WITH IDLE CONTROL SWITCHED OFF THEN SWITCHING IDLE CONTROL ON WILL GENERALLY MAKE THINGS WORSE.

Idle control is designed to help maintain a set idle RPM when extra load is placed on the engine by things like air conditioning, power steering, alternator load when turing on headlights, etc. Also it is used to hold idle speed a bit higher when the engine is dead cold.

It is very important to get the fuel and ignition table sorted out at idle before attempting to use idle control. I see so many people who have an engine yet to be tuned with the idle control turned on and wondering why the engine stalls, hunts and is generally unhappy.

Turn the idle control off, get the engine hot, set the base idle air (either butterfly position or idle bypass screw or DBW Translation Table) and sort out the fueling and ignition until the engine is idling smoothly.

For engines with big cams you can either raise the base idle speed or live with the fact that it has a rough idle. You can always just use the idle valve to bump up the idle speed when the engine is cold.

[Pascal]

Hey Mark! <3 Long time, isnt it? About idling, particolary Mitsu with M800 OEM. I did find few things most likely impossible but.... sh*t hapenss, isnt it? I notice for Mitsu EVO 9 that after you done with tunning the car and make it idle nicely and drivability is awsome to, that is important to restart the engine once more and redo it a bit. 3 in the row with same issue! I cant explain well why unfortunatlly. I know that does not make sense but 3 same cars of which 2 new one and have same tricky problem, maybe not really a problem but that small wierd detail. Any explanation maybe?

Pascal

[MarkMc]

The EVOs have stepper motors for their idle control so you need to make sure you use no integral gain at all (set to 0).

One other thing with Stepper motors is the initial position table says how many steps the motor should take on ECU power up. I usually have it step out (open) becasue the engine seems to start faster than having it step in (closed).

You can also open the idle bypass screw a bit to help your idle control. The factory has this closed a lot, maybe for emissions to give high vacuum on overrun...or something like that.

Another trick in the EVOs is to make sure you have the Recovery Time parameter for the Air Conditioning set to about 1 second. This gives the idle stepper a chance to stepp out before the A/C clutch kicks in.

[Mazi]

Little bit off topic...

At the moment it is possible to use two idleups, Air Con Increase and Power Steering Increase. OK! They are both external signals connected to ECU inputs. But I would like to idleup when ECU controlled cooling fans are running. I don't want to sacrifice an input pin or internal table. Is it possible to include this feature in one of next software revisions? Maybe as an additional parameter in Thermo Fan function or Idle Control Setup.

[PQatPIT]

But I would like to idleup when ECU controlled cooling fans are running. I don't want to sacrifice an input pin or internal table. Is it possible to include this feature in one of next software revisions? Maybe as an additional parameter in Thermo Fan function or Idle Control Setup.

This would be a great addition! Please...?!

[MarkMc]

Probably not a bad suggestion...actually something we have wanted for a while. I notify the software department.

[Pascal]

Hey Mark!

Did it couple of it lately (Mitsu) and still EACH of them have his own brain. Silly, right? But on the end all of them running nicely now. Thanks for tips!

Pascal

(When u r coming a bit to my shop?)