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3SGTE idle speed control valve always open


_pkmds
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Hello, searching for this problem like 3-4 months . My first tuned map i got was a mess. The tuner made the AC idle valve to manage the idle and the actual ISCV's duty cycle was like 10-20%. The car was boosting alright ,not any boost hesitation or behaviors like boost leak.

When another tuner made my final map we fixed and changed many things so the ISCV duty cycle went to 65% to hold the desired idle. The problem is that since then i have enough boost leak of this valve.

The stock ECU let's the valve open when you cruising until some RPMs or TP position(no idea specifically). In particular moment with G4+ is impossible to make it work like this because i did everything in parameters of ISCV adjustments.

The situation it's tested and 100% i have boost leak from there. Is there any other way to fix this problem or i need to install a non-return valve in this air hose to eliminate this problem?

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8 hours ago, Adamw said:

The idle valve is usually plumbed to both sides of the throttle as a bypass.  So under boost you have the same pressure on both sides of the valve.  

Dh1eQyF.png

Doesn't work like that in 3sgte. The isc valve has 2 ports one for cold status and one for idle. The link doesn't operate the valve correctly like it should thats why boost air has advantage to make boost leakage

6 hours ago, INSW20 said:

I have my idle valve set to close over about 5% TPS on my gen2 3SGTE, for what that's worth.

image.png.365e1e34893009897b72b2981ea1bf1c.png

I've been very happy with how my engine idles.  It's taking filtered air from the turbo inlet tube.

I was thinking to do the same. How so you have so low DC on warmed positions? How much Idle rpms you use ?

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3 hours ago, _pkmds said:

Doesn't work like that in 3sgte. The isc valve has 2 ports one for cold status and one for idle. The link doesn't operate the valve correctly like it should thats why boost air has advantage to make boost leakage

It can operate it however you want.  If you want the valve to close when throttle is open then set up your base position table to do that.  

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5 hours ago, _pkmds said:

Doesn't work like that in 3sgte. The isc valve has 2 ports one for cold status and one for idle. The link doesn't operate the valve correctly like it should thats why boost air has advantage to make boost leakage

I was thinking to do the same. How so you have so low DC on warmed positions? How much Idle rpms you use ?

Another local 3sgte owner rerouted his idle air plumbing to the throttle body inlet, so his IACV position can’t cause boost leaks.  Just depends on how your air plumbing is set up.

I’m not sure why our IACV positions are so different, but my idle is about 850-900rpm hot. The engine responds appropriately to changes in valve position, so I never considered that I may have any problems there.

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3 hours ago, Adamw said:

It can operate it however you want.  If you want the valve to close when throttle is open then set up your base position table to do that.  

Yes. I didn't know that i can change the axis load from rpms to TP main in 3D table. With this way it will fix my problem I'll try it today .

45 minutes ago, INSW20 said:

Another local 3sgte owner rerouted his idle air plumbing to the throttle body inlet, so his IACV position can’t cause boost leaks.  Just depends on how your air plumbing is set up.

I’m not sure why our IACV positions are so different, but my idle is about 850-900rpm hot. The engine responds appropriately to changes in valve position, so I never considered that I may have any problems there.

The IACV is the idle air conditioning valve? Or you mean the ISCV ? What engine revision you running? What's your valve registration? One is as slave and the other regular isc motor? If i set my warmed status duty cycles to lower values , the ECU automatically will increase the duty cycle until it reach the rpm target. So i checked how much Duty cycle it needs to reach 900rpm and i set it on 62.8% , otherwise I have unstable idle rpms which the engine starts bouncing because of idle ignition control. Anyways when you cruising and you put it on neutral  what rpms you've got? Mine revs to 1200-1300 because the idle ignition control is out of speed lockout and takes ignition angle target from the ignition table but if i adjust the ISCV to 30% DC it stops.. seriously theres so many things that noone can fix them and im looking all the time by myself

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51 minutes ago, _pkmds said:

Yes. I didn't know that i can change the axis load from rpms to TP main in 3D table. With this way it will fix my problem I'll try it today .

The IACV is the idle air conditioning valve? Or you mean the ISCV ? What engine revision you running? What's your valve registration? One is as slave and the other regular isc motor? If i set my warmed status duty cycles to lower values , the ECU automatically will increase the duty cycle until it reach the rpm target. So i checked how much Duty cycle it needs to reach 900rpm and i set it on 62.8% , otherwise I have unstable idle rpms which the engine starts bouncing because of idle ignition control. Anyways when you cruising and you put it on neutral  what rpms you've got? Mine revs to 1200-1300 because the idle ignition control is out of speed lockout and takes ignition angle target from the ignition table but if i adjust the ISCV to 30% DC it stops.. seriously theres so many things that noone can fix them and im looking all the time by myself

I meant "idle air control valve", I'm certain we're talking about the same thing, the little air valve on the bottom of the TB.  Mine is a Gen2.  I don't have any speed inputs into the ECU currently (91 cable speedometer, no ABS, no cruise sensor yet), so my speed lockout is "off".

Maybe start by turning idle ignition control off, closed loop idle off, double check everything and start with fresh idle tuning.  And of course save your current cal as a revision if you need to revert back.  Here are my settings, not saying this is ideal, but this seems to work well for my setup.

image.thumb.png.f73b32a1a733c05f17a8fcbdfd4ffb18.png

image.png.db8fb07ab45f20f27f73c99bf8787f9f.png

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to tune idle correctly there are many things acting on this at the same time.

First make sure your AFRs are in check from cold to warm. then disable idle ignition (fixed timing at target) have you main ignition table not higher than 3-4 degrees compared to your idle ignition timming, in the same area.

then tune your idle air control valve opening/% to get to target, then tune your fan/PS/hold steps, then turn your idle ignition on and close loop.

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21 hours ago, INSW20 said:

I meant "idle air control valve", I'm certain we're talking about the same thing, the little air valve on the bottom of the TB.  Mine is a Gen2.  I don't have any speed inputs into the ECU currently (91 cable speedometer, no ABS, no cruise sensor yet), so my speed lockout is "off".

Maybe start by turning idle ignition control off, closed loop idle off, double check everything and start with fresh idle tuning.  And of course save your current cal as a revision if you need to revert back.  Here are my settings, not saying this is ideal, but this seems to work well for my setup.

image.thumb.png.f73b32a1a733c05f17a8fcbdfd4ffb18.png

image.png.db8fb07ab45f20f27f73c99bf8787f9f.png

We have same settings expect that I have speed lockout enabled (which doesn't work because thr ISC valve is always "ON" how much Hz you set ? 250 or 200? 3D table works perfect tho. Thanks for the information

21 hours ago, dx4picco said:

to tune idle correctly there are many things acting on this at the same time.

First make sure your AFRs are in check from cold to warm. then disable idle ignition (fixed timing at target) have you main ignition table not higher than 3-4 degrees compared to your idle ignition timming, in the same area.

then tune your idle air control valve opening/% to get to target, then tune your fan/PS/hold steps, then turn your idle ignition on and close loop.

The afr is correct tho. In cold it has 13.5 when it goes to 50c then it has stable 14.7. when i tuned the ISC I turned off closed loop i saw how much actual DC values it needed to have the RPM target e.t.c. the problem is that my Idle ignition control is tuned around -5 , -2 and 0. The ignition table at idle cells is 15 degrees . If i reduce it it helps a lot but i have bad behavior because if i cruise between 1200-1500 rpm i have really low ignition angle and feels like the car is struggling to accelerate. I'll show you some screenshots

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22 hours ago, dx4picco said:

to tune idle correctly there are many things acting on this at the same time.

First make sure your AFRs are in check from cold to warm. then disable idle ignition (fixed timing at target) have you main ignition table not higher than 3-4 degrees compared to your idle ignition timming, in the same area.

then tune your idle air control valve opening/% to get to target, then tune your fan/PS/hold steps, then turn your idle ignition on and close loop.

Untitled.jpg.9092f5d4346e9738cf05ade28c957531.jpg

the idle while im moving with neutral is around the red circle.with these values in this cells from 1300-1500 rpm i have 1100-1200 i dont know what will happen if i change from 10degrees at 1500rpm to 5 degrees and negative like -5 or -2 degrees at 1000 .technically i think it will work but is it bad if i do it like this? it will affect anything? i tried like two months ago to increase the RPM lockout of idle ignition control from 10kph to 50-60 it worked tho but because the ignition angle was negative the exhaust was doing some light shootgun shoots like i had anti lag . if i place negative ignition angle on high rpm but on far upper right cells it will do the same ? lol

Untitled1.thumb.jpg.845dcf3b66768640cde79cdb74534257.jpg

and these are my settings on idle.

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On 8/5/2022 at 7:01 AM, _pkmds said:

We have same settings expect that I have speed lockout enabled (which doesn't work because thr ISC valve is always "ON" how much Hz you set ? 250 or 200? 3D table works perfect tho. Thanks for the information

The afr is correct tho. In cold it has 13.5 when it goes to 50c then it has stable 14.7. when i tuned the ISC I turned off closed loop i saw how much actual DC values it needed to have the RPM target e.t.c. the problem is that my Idle ignition control is tuned around -5 , -2 and 0. The ignition table at idle cells is 15 degrees . If i reduce it it helps a lot but i have bad behavior because if i cruise between 1200-1500 rpm i have really low ignition angle and feels like the car is struggling to accelerate. I'll show you some screenshots

mine is set to 200hz.  why are you running negative ignition advance at idle?  the idle ignition table is a lookup table, not an "adder" table.  so if you set idle ignition to -5, you will be firing the coil at -5 degrees.   my 3sgte also seems happy idling at about 15 degrees

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On 8/7/2022 at 4:40 PM, INSW20 said:

mine is set to 200hz.  why are you running negative ignition advance at idle?  the idle ignition table is a lookup table, not an "adder" table.  so if you set idle ignition to -5, you will be firing the coil at -5 degrees.   my 3sgte also seems happy idling at about 15 degrees

no idea, my tuner set it up like this .i dont know the benefit of it. the ISC valve worked with the way you said to me. thanks man

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Just FYI there is also some fine control of the idle valve with the shutter plate spring mount.  If you remove the ISCV from the throttle body and look in there and with the key on move the ISC position from 0 to 100% you may notice that even at 0% open there is a small leak.  You can loosen the screws holding the end plate on (and rotate it slightly to make the shutter close fully at 0% and then retighten.  Note: To do this test you will need to make sure your min and max ranges allow 0-100% and then you adjust the current running location in the base position table up and down.  Also while you have the ISCV off I recommend cleaning it out and lubing it as they get sticky after a while and their performance/resolution suffers.  I like gun lube as it tends to stay in place longer than most other lubricants I've tried on these.

Most 3SGTE I set idle timing to about 18 target, 0 min, 30 max.  If your engine won't idle properly at 15-20 degrees advance, then you are probably running too much air through he bypass screw (gen1/2 3sgte) or the base throttle position is too high (Gen 3/4/5).  Or you may have some other vacuum leak.

Most 3SGTE I also set the base position table to based y-axis on MAP and set the base position to 0 above 105 or 110 kpa.

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