ECMlink Can not set ISC position

[AWD-Tony]

So this entire time I thought my ISC was bad since I couldn't adjust it. Well I just installed the new one but it's doing the same thing. With diagnostic & timing pins grounded, it will not move from 9. When I remove the ISC, it does move when key is turned on and off. I checked resistance and they're 30 ohms across the board. Supplied 6V and it does twitch, BUT the new one does not. There are no boost or exhaust leaks.

 

[pauleyman]

Is the throttle closed and are your isc drivers ok in the ecu?

And is the throttle body ground bracket present?

 

[AWD-Tony]

Is the throttle closed and are your isc drivers ok in the ecu?

Throttle is closed and I just got my ecu back from link and they didn’t find anything wrong w it

And is the throttle body ground bracket present?

What’s that? I’ll have to look into it

And is the throttle body ground bracket present?

If it’s the bracket that bolts to the CAS, it is not there

 

[pauleyman]

If it’s the bracket that bolts to the CAS, it is not there

No. It's a little teeny bracket attached to one of the throttle body bolts. Doesn't appear to do anything. It's actually a ground for the idle position switch. Intake manifold ground must also be present. These two let ecu know throttle is closed.

 

[motomattx]

Is your closed throttle switch still present and set right and working properly is what they are getting at, the ecu wont try to use the isc motor to set an idle if it doesnt see that the throttle plate is closed all the way.

 

[pauleyman]

https://www.google.com/search?q=dsm..._AUICigC&biw=360&bih=512#imgrc=mkWJMMUAyMAftM:

This thing

 

[miliman13]

Also as of late what ends up being the culprit after a long tedious search is the fiav itself.

A small piece of metal warps back and forth with coolant temps... And gets deformed and brittle over time....
Few threads on here diagnosed this .

 

[AWD-Tony]

Is your closed throttle switch still present and set right and working properly is what they are getting at, the ecu wont try to use the isc motor to set an idle if it doesnt see that the throttle plate is closed all the way.

Throttle closed switch is there and set correctly. It grounds when throttle is closed.

No. It's a little teeny bracket attached to one of the throttle body bolts. Doesn't appear to do anything. It's actually a ground for the idle position switch. Intake manifold ground must also be present. These two let ecu know throttle is closed.

I do not have that small bracket but the idle switch is working properly and does ground when throttle is closed. It's working properly from what I can see in link. Do I still need that bracket even if link sees that it's working?

Also as of late what ends up being the culprit after a long tedious search is the fiav itself.

A small piece of metal warps back and forth with coolant temps... And gets deformed and brittle over time....
Few threads on here diagnosed this .

I'll have to research this. Haven't seen anything about this. Thanks

https://www.google.com/search?q=dsm..._AUICigC&biw=360&bih=512#imgrc=mkWJMMUAyMAftM:

This thing

My throttle body as 4 ports and the google pic you attached only has 2. And I definitely do not have it.

https://www.google.com/search?q=dsm..._AUICigC&biw=360&bih=512#imgrc=mkWJMMUAyMAftM:

This thing

I used voltmeter and both circled areas have ground. Do I still need that bracket? Thanks

No. It's a little teeny bracket attached to one of the throttle body bolts. Doesn't appear to do anything. It's actually a ground for the idle position switch. Intake manifold ground must also be present. These two let ecu know throttle is closed.

Intake manifold ground is there. If I see the throttle switch is closed in link, doesn't that mean the ecu sees the same?

When it's in open loop, the ISC sits at 0, and in closed loop it's at 9. When engine is off, it's at 90, and when I start it back up it jumps to 120 and slowly drops to 0 with RPM settling. All this is at full operating temp.

 

[steve]

When it's in open loop, the ISC sits at 0, and in closed loop it's at 9. When engine is off, it's at 90, and when I start it back up it jumps to 120 and slowly drops to 0 with RPM settling. All this is at full operating temp.

That's telling me that the ECU can't cause the idle speed to drop down to what you have it set to using the BISS.
Either you have a ISC that isn't moving, you have some other way for air to bypass the butterfly, or the BISS isn't adjusted correctly.

From the earlier pictures of your TB I'd suggest capping off the nipples rather and looping them. Looping then can create a path from the port on one side of the butterfly to the other side. (An air bypass)

 

[AWD-Tony]

That's telling me that the ECU can't cause the idle speed to drop down to what you have it set to using the BISS.
Either you have a ISC that isn't moving, you have some other way for air to bypass the butterfly, or the BISS isn't adjusted correctly.

From the earlier pictures of your TB I'd suggest capping off the nipples rather and looping them. Looping then can create a path from the port on one side of the butterfly to the other side. (An air bypass)

That makes sense, Steve. I bought the car like this and trying to get everything sorted out and tuned correctly has been so tedious. Where can I purchase caps? Thanks!!

That's telling me that the ECU can't cause the idle speed to drop down to what you have it set to using the BISS.
Either you have a ISC that isn't moving, you have some other way for air to bypass the butterfly, or the BISS isn't adjusted correctly.

From the earlier pictures of your TB I'd suggest capping off the nipples rather and looping them. Looping then can create a path from the port on one side of the butterfly to the other side. (An air bypass)

Dorman makes the caps. Thanks!!

That's telling me that the ECU can't cause the idle speed to drop down to what you have it set to using the BISS.
Either you have a ISC that isn't moving, you have some other way for air to bypass the butterfly, or the BISS isn't adjusted correctly.

From the earlier pictures of your TB I'd suggest capping off the nipples rather and looping them. Looping then can create a path from the port on one side of the butterfly to the other side. (An air bypass)

Just capped all 4 ports. Still no change =(

 

[1990TSIAWDTALON]

Put a BB in the vacuum lines on the TB and call it a day. It makes it a double plug. My caps always get brittle and then leak, the ones I used didn't care for heat very much. Just thowin that out there.

 

[AWD-Tony]

Put a BB in the vacuum lines on the TB and call it a day. It makes it a double plug. My caps always get brittle and then leak, the ones I used didn't care for heat very much. Just thowin that out there.

I can see that. The caps I just purchased does not look like they'll last very long with heat and cold cycle. Either way, it didn't fix my original problem of setting the ISC

 

[steve]

Either way, it didn't fix my original problem of setting the ISC

I would have been surprised if that's all it took.

 

[mitsubishikid]

Did you try, in ecmlink, to simulate the idle switch, via the TPS?

 

[AWD-Tony]

Did you try, in ecmlink, to simulate the idle switch, via the TPS?

I haven't. Guess that's easy enough to give it a shot. Only reason I didn't was because I know the idle switch is working properly.

 

[19gsx91]

^^ What Mitsubishikid said. That would be my first step to see if it's an issue in the ecu or mechanical.

 

[91talonts1]

Trying to follow along, haven't looked at the log yet but from the op it sounds like you're doing this with the diagnostic pin grounded?

When you ground that pin the ECU is supposed to lock the ISC at around 9-10, this keeps the isc from moving around while you adjust the biss to achieve target idle speed. This method should end up with iscpos somewhere around 20-40 once you unground that pin.

 

[AWD-Tony]

Trying to follow along, haven't looked at the log yet but from the op it sounds like you're doing this with the diagnostic pin grounded?

When you ground that pin the ECU is supposed to lock the ISC at around 9-10, this keeps the isc from moving around while you adjust the biss to achieve target idle speed. This method should end up with iscpos somewhere around 20-40 once you unground that pin.

Yes diagnostic pin was grounded. How far is the BISS usually turned in or is it mostly out?

BISS was in more than half way

 

[91talonts1]

There's no right or wrong amount for the biss to be turned, just wherever it ends up. They usually end up farther in than out when nothing's leaking though.

 

[PlanZero]

I suggest you pull the ISC leave it plugged in and rest it stop your TB. Turn the key to ON you should see the pintle moving in and out as you turn the key. After having tons of idle issues and messing with used parts I've found this to be the best way to check.

Edit: sorry just reread your original post. Is the new unit brand new or used? I know with a brand new unit you have to do some kind of procedure to let the ecu learn the new IAC. I also had a brand new Standard brand IAC almost dead out of the box (pintle twitched, that's it). I just buy them used now.

 

[steve]

Except all the way in or all the way out...

On my car it's about 1.5 turns from all the way in but it's started idle surging lately warning up so it's time to look for leaks and check my FIAV.

 

[PlanZero]

^ I bypassed my FIAVs, one with a plate and the other I just popped the freeze plug and screwed the FIAV all the way down. Haven't noticed any (negative) difference on either car, even in the middle of winter.

I've also found JB weld Steel Stick to be useful in about 100 places on a DSM. If you never plan on using those vac ports smush a little steel stick in there and wipe off the excess.
Also I have think it's a #6 O ring on the BISS. Replace it while your messing around in there.

 

[AWD-Tony]

I suggest you pull the ISC leave it plugged in and rest it stop your TB. Turn the key to ON you should see the pintle moving in and out as you turn the key. After having tons of idle issues and messing with used parts I've found this to be the best way to check.

Edit: sorry just reread your original post. Is the new unit brand new or used? I know with a brand new unit you have to do some kind of procedure to let the ecu learn the new IAC. I also had a brand new Standard brand IAC almost dead out of the box (pintle twitched, that's it). I just buy them used now.

Yes the ISC I purchased is new but when I applied 6 volts it didn't twitch so put the original one back in. The pintle does move in and out with key cycle.

^ I bypassed my FIAVs, one with a plate and the other I just popped the freeze plug and screwed the FIAV all the way down. Haven't noticed any (negative) difference on either car, even in the middle of winter.

I've also found JB weld Steel Stick to be useful in about 100 places on a DSM. If you never plan on using those vac ports smush a little steel stick in there and wipe off the excess.
Also I have think it's a #6 O ring on the BISS. Replace it while your messing around in there.

I'm thinking about completely shutting the FIAV. I replaced the shaft seals and TB gaskets but left the FIAV alone at that time. Also replace the O ring for BISS. JB welding those ports is something I'll consider when the caps get old.
Thanks

Except all the way in or all the way out...

On my car it's about 1.5 turns from all the way in but it's started idle surging lately warning up so it's time to look for leaks and check my FIAV.

That's what I've read, about two turns from all the way in. My car idles best when it's completely in all the way but I've also read that that actually causes a vacuum leak. IDK??? It's discouraging when you try everything, and nothing changes.

 

[PlanZero]

I just want to add that I tried to screw in the FIAV on one TB but that sucker wouldn't budge and it wasn't something I felt comfortable using brute force on. The bypass plate is only a couple bucks so may be something to consider beforehand.

 

[motomattx]

Are your coolant lines going to your fiav or are they looped (eliminated).