What is the trick to getting IACV right? Also CLL stuff?

[bazzasti]

I've installed the Link idle air control valve and got it working but found setting it up is one of the hardest things I've had to do with regards to tuning.

I get it perfect at a certain air temperature but as soon as the air temperature changes it turns to sh!t and there is no air temp compensation, only water.

Also what does the Link IACV do under boost? Does it close up completely or do I need a one way valve - I'd assume not because the stock Subaru units don't.

Another question is the Subaru stock computer remembers the CLL adjustments made through the map so after driving for 15 minutes the car hits the perfect AFR targets for cruise etc very easily and a lot quicker. Is this something the link does or could do in the future? I get around 10L / 100 km country which is exactly what my Microtech gave me and it didn't have CLL so for such a refined unit I am going to pushing it for a lot more and would like to see 9L / 100 km

[ashesman]

Setting up IAC is not that hard if you follow logical steps:

1. Make sure the valve is plumbed correctly and wired to an auxiliary channel that supports ISC solenoid.
2. Select the auxiliary channel as ISC solenoid and set the frequency to 200Hz (very important).
3. Make sure the car is properly tuned from cold to hot.

4. Test the ISC valve by entering different duty cycles.  Higher numbers should result in a higher engine RPM.  Make sure that when the DC is set to 0% the engine idles at about 400 RPM (adjust the throttle plate screw).  Adjust the screw on the ISC valve to give approx 50% DC at your normal hot idle speed.

5. Set the ISC mode to open loop.  Start the car from cold and adjust the ISC solenoid duty cycles to get approximately the desired idle RPM at each temperature as the engine warms up.
6. Switch the ISC mode to closed loop.  Start with the following settings:
   1. Min Clamp = 10
   2. Max Clamp = 90
   3. TP Lockout = 1.5% (make sure TPS is spanned correctly)
   4. Speed Lockout = none (unless you have speed on DI1)
   5. RPM Lockout = 500
   6. Deadband = 10 RPM
   7. Fan Step and Power Steer step = 0
   8. Set desired target RPM's
   9. Proportional gain = all 1
   10. Derivative gain = all 2
   11. Anti stall gain = all 8
   12. Startup step = all 10
   13. A/C step = all 0

7. Start again from cold.  As the engine warms up, watch the Idle Status in the runtime values tab.  When it says Target RPM, look at the Idle Position value.  That is the DC required to make your target RPM.  Enter that number into the Base Position table at the appropriate temperature.

8. Trim A/C and fan step values as required.

I hope that helps.  My subaru runs an LEM G3 and factory ISC valve.  I have absolutely no issues regarding IAT compensation.  The IAT varies from 10 to 80 degrees but ISC control is always good.  Those two port solenoids work really well when setup correctly...

[bazzasti]

Okay the car is tuned well from cold to hot although at the moment I just want the hot idle to work properly.. Now I've used your figures and the car is behaving about the same to be honest. I did some more testing and it seems the main problems are:

1: The Link solenoid seems very erratic. I've set the minimum clamp to about 27.5 and this is where the solenoid is closed and any less than 27.5 and it opens up the other side. The car idles at about 450-500 rpm when the solenoid is closed or disconnected. Now setting the base idle using the open loop setup is where things get interesting. I set it to 45 and it idles fine from say 80-100'C. Several restarts later and all of a sudden 35 is the new point. I then watched the solenoid open and close and it seems that 45 set once is never 45 again. Why is it doing this? I would've thought that 35% is always a certain gate open amount?

2: I did some logging and when boosting the solenoid is open - sometimes 60%. Shouldn't it close the gate so I am not effectively having another wastegate?

Also above you said I can adjust the link solenoid, how do I do this? It seems it's locked in position?

[ashesman]

What channel do you have the ISC solenoid wired to?  For a two wire solenoid on an LEM G3 it must be wired to Aux 1 or 2 or Aux 5 to 6.  Not Aux 3 or 4 or ignition or injection channels.  It must be wired to a flywheeling channel.  It must be setup to operate at 200 Hz.  If it is plumbed correctly from one side of the throttle body to the other then it wont matter what it is doing under boost.  In fact having it open effectively enlarges your throttle body.  Those solenoids always provide super stable idle in open or closed loop mode so there is something a little wrong with your setup.  The adjustment on the solenoid is got to by removing the glue and turning it with an allen key.  If you get an idle of 450-500 RPM with it closed then there is no need to adjust it.  Make sure your throttle isn't sticking or dirty, that could cause the variation in duty cycle.

ALL of the above stuff MUST be correct for the solenoid to operate properly...

[bazzasti]

Interesting, that makes a few things more clear. It's a LINK G3 and I think I'm using AUX 5, and it's set to 200 hz (I rang up and spoke with someone when I set it up)..

The plumbing is very interesting because RS 1989-1994 and WRX MY92 - MY98 all use fresh air as the idle air source. The MY99-00 uses the cold side intercooler air to the manifold which therefore does act like a bigger throttle body. I've just set mine up like the older WRX / RS. However now that you mention the above I'll replumb it.

Also something else to remember is all the WRX and RS throttle bodies and the idle air control valves are heated with coolant water - I always wondered what they did that for but now I am thinking it's to help keep the idle air at a constant temperature. Anyway will play around and see how it goes. Cheers and thanks

[ashesman]

I think the heating is to prevent the valves from freezing in really cold climates due to moisture in the air condensing on the inside of the valve.  Just out of interest, how come you didn't use the factory IAC valve?  Aux 5 is an OK channel to wire the ISC valve to.  Make sure the positive side is wired to an ignition switched supply, not fed directly from the battery.

[bazzasti]

Yeah I think you're right regarding the coolant water, I was hoping it would help the idle but it didn't. I setup the car today and had it running fine with the idle in 25'C manifold air temp and did many test runs from 80'C to 100'C ECT without an issue.

Then I went off to Calder Park and several drag runs (well actually about 20), and as soon as the air heats up under the bonnet and it just fails terribly in both open and closed loop - I had to add 4 units to get the idle to come up. It might work okay for 2L / TD04's but it really struggles with anything bigger by the looks of things. Btw ran an 11.6 @ 195 kph which was good  still 0.2 off the Microtech but I'm getting there. It took me about 10 runs with the data logging to sort out the gearing and boost .

Also I didn't use the factory IAC valve as I had it removed for when I ran the microtech and MY99 ones are rare and near impossible to replace without forking out huge $$.

P.S. I have it connected to the positive terminal on one of the coils. I am thinking of wiring it elsewhere to test but I highly doubt that would be the issue.

[ashesman]

Wiring it off the coil feed is a bad idea as there is already huge current draw on the coil fuse, but like you say is not going to fix the problem.  I am unsure why you are having these issues.  If your CL idle is set up properly it shouldn't matter if the idle valve is changing with temperature as the  closed loop system will  just compensate for it.  What does the idle status say when it is in closed loop mode while the problem is occurring?

Good effort on your 11.6.  I can assure you that you can get to at least the same time running our ECU as the Microtech.  There is no horse power in ECU's, just in tuning...

[bazzasti]

I think I can see the problem. In Open Loop she idles fine but struggles a little when you load up the alternator or the air temp changes to much. However when the throttle is opened the idle duty goes to my base setting - VERY GOOD.

The problem with the Closed Loop idle is it has some weird logic in it. When the throttle is opened and the car revs up to 4500 rpm for instance it opens up by about 6% above the base. Say base is 40, it will hit 46 and the idle will take ages to come back down from 1500-2000 rpm to 900 rpm and you usually see RPM Lockout - idle high or something similiar which prevents it from coming back down quickly as well.

I want the IACV to shut to my base setting when the throttle opens. Having it open reduces my engine braking effect around a racetrack and it's been proved that unless running over 300 kw atw a bigger throttle body doesn't help in anyway for all conditions. Is there anyway to add some more functionality into the closed loop?

On a positive note I was testing out the launch control today - you sure got that logic right, it's sensational, can't wait to use it at the drags

P.S. I know there is no difference in potential times between the Mtech and the Link I am hoping for a <11.4 when I get eveyrthing sorted 100%

[ashesman]

The duty cycle goes up by about six percent.  When the engine comes back to idle it will hold at 6% above for the 'hold time', then 3% above for the 'hold time' after that it will drop back to the base and attempt to trim using closed loop.  If you see a RPM Lockout message then you have your RPM lockout value set too low.  It should be set to about 500 RPM. 

The loss of engine braking is partially due to using no speed digital input.  Your speed lockout would help prevent idle control from operating while the vehicle is moving.

[bazzasti]

Okay I've got the IACV working pretty good now. I had to wire up the power steering digital input to a switch on the dash and set the power steering value to 4% to allow a more steady idle at higher IAT. At low IAT it's fine without it. I'll eventually hook that to an analogue out to get the air temperature compensation working perfectly, but at the moment I am just finding the optimum change over tempature.

I don't think my Wideband does voltage compensation which means it's pretty much useless for doing closed loop due to battery voltage variances. The wideband output voltage for 14.7 @ 13 volts is not the same as 12 volts - DAM annoying as I found during the day it was perfect, come night time and it was all over the shop.  So I've just set it up to do the idle @ 14.1 and it works a treat, cold start is awesome and very stable now.

The last thing I am setting up is the boost control which is proving quite hard to get it consistently right. at different air temperatues. However I've setup a dual map. Map 1 has nothing, so the wastegate is off. Map 2 has the wastegate values and is activated when boost reaches about 14 psi. This improved spool very nicely and also seems to have helped a lot in controlling the boost. However I'm still not entirely happy, what else do you recommend to get it right?

[bazzasti]

Also fuel related, but I noticed that when moving the air con trim is 0. But when stopped it's at 0.01 ms? I would like to be able to have it adding fuel when moving, is this possible?

[ashesman]

The air con trim does not change when the vehicle is moving or stopped if that is what you mean?

Start setting up your boost control with a 2D table.  Start the table at about 2000 RPM with the lowest value at 0% (to prevent the solenoid clicking at idle).  After that put the DC to 100% for fastest spool up and then enter the required DC for the boost value you want.  The actual numbers vary heaps depending on your engine.  Also use 20Hz duty cycle.  You can use the IAT and ECT boost trims to compensate.

We recommend Innovate LC-1 WB controllers, they seem to be pretty good.  Not many controllers work at low voltages as they need a certain voltage to drive the sensor heater properly.  If you sensor is too far back it will be harder to heat requireing a higher voltage...

[bazzasti]

That's interesting. My air con trim and fan trim seem to be 0 unless at idle where they goto their trim points. Any ideas?

The air con is working perfectly - love the clutch fan stuff ie where you can turn the air con off at X% throttle - REALLY works well.

Yeah I've done all that in the boost stuff and setup the ECT and IAT nicely. Just hard to get 20 psi from 0'C to 44'C.

[Richard McGeachy]

Make sure that when the DC is set to 0% the engine idles at about 400 RPM (adjust the throttle plate screw).  Adjust the screw on the ISC valve to give approx 50% DC at your normal hot idle speed.

At what engine temp should I set the DC to 0% and adjust the throttle plate screw?

currently my idle starts at 1300rpm cold and settles @ 800rpm hot. corresponding DC %'s 44 down to 30% hot.

Also what is the trick to the pro & deriv gain + anti stall. i understand the principles, but i'm trying to get the settings right.

[ashesman]

Set the throttle position at running temperature so that about 0% DC (ISC solenoid blocked off) gives a idles speed of about 500RPM.  This ensures that in any idle speed failure the engine will comfortably idle at 500 RPM (not cold!) and relieves the idle control of trying to deal with an engine that tends to stall.