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EVO 5 Link G4 PNP hunting idle

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hi there,

I am just getting the car ready to get tuned after this lockdown. an issue i am currently having is on cold start the idle hunts from 2000rpm to about 3000rpm. 

The ecu was tuned on the previous owners car. Im assuming he wouldve been running the same idle control stepper as factory. I have already set the injector settings as per the injector manufacturers specifications.

I am wondering if this an actual idle control issue because it still does the same even once its warmed up. or should i maybe pull the idle stepper motor off and clean it or something. 

Ultimately i would like to have the car at least idling nicely before i take it in for a tune.

Can upload the idle control settings if that helps

 

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There is no idle valve assigned so the last user probably didnt have one.  The RPM bouncing around is it hitting the over-run fuel cut.

Go into Aux outputs an set Aux 5 ,6, 7 & 8 to ISC Stepper so it looks like below.  Then do a store (Control+S), then turn off ignition for about 10 seconds (to home the idle valve) before turning back on and restarting.  Do another log then so we can see if it is closer.

6nE1wFR.png

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From that Im not convinced the idle valve is actually working.  In the attached tune I have made some adjustments to close the valve more to see if it has any influence.

Can you load this map in and give it a try.

Try this.pcl

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18 minutes ago, Adamw said:

From that Im not convinced the idle valve is actually working.  In the attached tune I have made some adjustments to close the valve more to see if it has any influence.

Can you load this map in and give it a try.

Try this.pcl 38.9 kB · 0 downloads

thank you very much adam. noob question. how do i load that map?

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Connect to the ecu, then go >file>open and choose that file. Click yes when it asks if you want to load the file or something to that effect.  Do a store afterwards.

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19 hours ago, Adamw said:

Connect to the ecu, then go >file>open and choose that file. Click yes when it asks if you want to load the file or something to that effect.  Do a store afterwards.

i gave it a go. its a lil better for the first few seconds but then goes back to normal. it was only fluctuating 400rpm then went back to the same as before

evo hunting idle 3.pcl evo hunting idle 3.llg

i have measured the resistances between the power pins and the other 4. all resistances are between 34 and 36 ohms. which according to the specs is a lil bit off. i believe the range is supposed to be 28-33 ohms. may have to look at either checking the idle stepper motor position just in case its some how changed. and if that fails try another iscv

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Im very suspicious the idle valve is not working.  Have you checked there is +12V on the two center pins with ign on? 

One last try, this map will force the idle valve fully closed (if the valve/wiring does actually work).  If it is still revving to the moon with this one then the valve is not working - or air is getting in some other way like the throttle blade is open too far or a big air leak etc. 

evohuntingidle5.pcl

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On a side note adam. Since it was hunting prior to the isc stepper actually being  switched on aux 5 -8. And things havnt changed. Logic is telling me there may actually be an air leak somewhere like you have suggeste.

 

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Oh and i just remembered. My bov is modulating open/closed while it has this hunting issue. I will try disconnecting bov and have the 10psi spring hold it down and see if it still hunts

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Have checked the wiring loom pinouts etc from iscv to the ecu. serviceable. i rigged up my old iscv externally so i could visually confirm valve movement. it is indeed moving, therefore i can pretty confidently say that the iscv is alright. i cant find any vacuum leaks either and have checked base throttle plate position which is in the correct closed position. im all out of ideas :(

i managed to set the base idle set screw on the throttle body and it got significantly better. the log is below. it now only fluctuates between 1600- 2200. it is still hitting over run fuel cut. 

evo hunting idle 7.llg

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The RPM still shots straight up until it hits the limiter.  So air is getting in somewhere.  Either the throttle blade/bypass is not closed enough, the idle valve is not closed or you have air getting in through a leak.  

I cant remember what the Evo 5 idle valve looks like but you should be able to pull the housing off and either visually see if it is shut or try blowing through it to confirm.  If that looks ok then put the valve back on and adjust either the throttle stop or BISS screw if it has one so that it barely idles - say 600/700RPM.

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