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B4 with linkg4+ High idle


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#1 Mr Legacy

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Posted 11 July 2017 - 12:46 PM

Hi guys,

I have recently had a LinkG4+ installed in my B4

It now has a high idle (1100-1200rpm) before it was 600ish.

The ecu is set to 700 but it won't go down. It thinks the iacv valve is shut.

Iacv has been checked and cleaned, wiring has been verified also.

When I unplug the iacv the revs jump up so it is definitely working.

Revs also hold momentarily between gear changes which may be related.

Any suggestions would be great!

#2 Barbbachello

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Posted 11 July 2017 - 01:34 PM

I assume you have a single turbo and manual B4? I dont think Links support auto or the twin turbo setup


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#3 duncanm

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Posted 11 July 2017 - 01:50 PM

Try blanking off the IACV?  Maybe you have an vacuum leak.



#4 Mr Legacy

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Posted 11 July 2017 - 04:48 PM

It's a manual TT. The tuner used a spare output to drive the ecv valve. The icv is manual.

#5 Mr Legacy

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Posted 11 July 2017 - 07:22 PM

I will try to blank off the iacv. How would you go about that. I haven't had a good look yet.

#6 duncanm

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Posted 11 July 2017 - 10:09 PM

mmm...  easiest would be to just block off the whole intake.

 

Another idea -- is your throttle cable slack enough at idle (ie: not holding plate open a bit).  Nice and clean, too?



#7 Mr Legacy

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Posted 12 July 2017 - 09:53 AM

[quote name="duncanm" post="613916" timestamp="1499774962"]mmm...  easiest would be to just block off the whole intake.
 
Another idea -- is your throttle cable slack enough at idle (ie: not holding plate open a bit).  Nice and clean, too?

I'll check that also!

Any idea if iacv is the same unit across ej205,207,208 for 01-07 wrx?


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#8 Mr Legacy

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Posted 13 July 2017 - 11:50 AM

Blanking off iacv fixes the high idle.
Also the neutral switch isn't working anymore as I don't think the link supports it.
Not sure if that's an issue.

There is 12v at the plug of iacv. Hard to tell on the 3rd white wire.
Tuner assures me that he has checked it with a node light.


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#9 duncanm

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Posted 13 July 2017 - 12:55 PM

three wires to the IACV - power, GND, and PWM (control) from the ECU, which toggles between 0V and 12V at some frequency (kHz?).

 

Measure the voltage on the PWM signal - FSM says it should be about 3V.

 

Maybe the voltage range in the ECM is wrong -- eg: it thinks 'off' is 4V and fully open 10V, or something.  Can you get to those numbers? 

 

I just did a bit of googling -- the Link G4 closed-loop idle control uses a (fairly standard) PID type control loop - the parameters all are settable, so maybe the loop parameters are wrong. 

 

http://www.supraforu...n-idle-control/
 



#10 Mr Legacy

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Posted 19 July 2017 - 10:00 AM

three wires to the IACV - power, GND, and PWM (control) from the ECU, which toggles between 0V and 12V at some frequency (kHz?).
 
Measure the voltage on the PWM signal - FSM says it should be about 3V.
 
Maybe the voltage range in the ECM is wrong -- eg: it thinks 'off' is 4V and fully open 10V, or something.  Can you get to those numbers? 
 
I just did a bit of googling -- the Link G4 closed-loop idle control uses a (fairly standard) PID type control loop - the parameters all are settable, so maybe the loop parameters are wrong. 
 
http://www.supraforu...n-idle-control/
 


I think I worked it out with the help of the tuner. The base position for the iacv was set to high. There is a function that lets you see the target vs actual and it works out the error and suggests what the base position should be for the desired target.
Seems to be idling nicely at 700 now !

Cheers!


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#11 duncanm

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Posted 19 July 2017 - 01:33 PM

awesome.. it had to be something simple like that.



#12 Mr Legacy

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Posted 19 July 2017 - 01:43 PM

awesome.. it had to be something simple like that.


I now have to setup the fan and a/c idle up as the car nearly stalls when idling at 700 once either cut in.

The tuner explained how to do it through digital outputs and setting up a 3D table to work alongside the actual aux output.
Interesting stuff!


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#13 CodeBurn3r

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Posted 21 July 2017 - 07:37 PM

Hey mate, can you let us know where you found the option for the idle control set?
mine holds a high idle for a good 20-30 seconds 90% of the time.. no vac leaks.. it just seems to take ages before it decides to go back to low idle.


also, random thing.. but does yours always throw the primary fan on?

mines always got the primary fan on with ignition, but i know they are set right cause when driving, i can log the fans and they operate correctly, just seems that when at 0km/h it defaults to being on.


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#14 Mr Legacy

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Posted 29 July 2017 - 07:59 PM

What temp have you got your fans set at? There is a feature that keeps them on with ignition which is meant for Motorsport if using with an electric water pump.


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#15 Mr Legacy

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Posted 29 July 2017 - 08:01 PM

[quote name="Mr Legacy" post="614283" timestamp="1501322388"]What temp have you got your fans set at? There is a feature that keeps them on with ignition which is meant for Motorsport if using with an electric water pump.


I'll have a look tomorrow about the idle. Have you got closed loop control on?


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#16 CodeBurn3r

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Posted 16 August 2017 - 01:20 PM

slack with getting on here sorry.
Yeah closed loop on.

temps are setup as per Factory options (extracted it from the base v3/4 tune)

it operates correct in all ways except it seems to not detect that its not moving
 


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