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-   -   na6 pwm idle valve stuck after warmed up (https://www.miataturbo.net/megasquirt-18/na6-pwm-idle-valve-stuck-after-warmed-up-101093/)

Chance Nguyen 09-12-2019 03:52 AM
na6 pwm ISCV stuck after warmed up
 
I'm running an mspnp2 on a 1990. During warm up or the first 10-30 mins after the car starts up, the pwm isc valve functions normally. Once I get it warmed up and drive it around, maybe 180degrees coolant temp, my iscv refuses to adjust, it gets stuck open, leaving my rpms idling at 1200 when its set to 850. Even when using the pwm iscv testing on tunerstudio, it refuses to react to any change. it doesn't seem to directly correlate with coolant temps since sometimes if I restart the car I can get it to work again but stops after 20 mins of driving again. I even replaced the iscv and attempted to check the resistance when this happens but didn't do nutin. Has anyone heard of this problem or knows how it could be fixed?

andym 09-12-2019 08:59 AM
Originally Posted by Chance Nguyen (Post 1548612)
I'm running an mspnp2 on a 1990. During warm up or the first 10-30 mins after the car starts up, the pwm idle valve functions normally. Once I get it warmed up and drive it around, maybe 180degrees coolant temp, my idle valve refuses to adjust, it gets stuck open, leaving my rpms idling at 1200 when its set to 850. Even when using the pwm idle valve testing on tunerstudio, it refuses to react to any change. it doesn't seem to directly correlate with coolant temps since sometimes if I restart the car I can get it to work again but stops after 20 mins of driving again. I even replaced the idle valve and attempted to check the resistance when this happens but didn't do nutin. Has anyone heard of this problem or knows how it could be fixed?
Post a copy of your tune so we can see if something is wonky on there.

Chance Nguyen 09-12-2019 12:17 PM
2 Attachment(s)
Here is me tune. I'm experimenting with decel burble so dont mind those 15 kpa rows in the ignition and ve table(unless it somehow messes with my pwm idle valve.) The problem happens on the base map too.

LeoNA 09-12-2019 05:43 PM
With a stand alone you don't need the idle valve. The ISCV is more adequate. Cut out a block off gasket for the IV.

Originally Posted by Chance Nguyen (Post 1548612)
I'm running an mspnp2 on a 1990. During warm up or the first 10-30 mins after the car starts up, the pwm idle valve functions normally. Once I get it warmed up and drive it around, maybe 180degrees coolant temp, my idle valve refuses to adjust, it gets stuck open, leaving my rpms idling at 1200 when its set to 850. Even when using the pwm idle valve testing on tunerstudio, it refuses to react to any change. it doesn't seem to directly correlate with coolant temps since sometimes if I restart the car I can get it to work again but stops after 20 mins of driving again. I even replaced the idle valve and attempted to check the resistance when this happens but didn't do nutin. Has anyone heard of this problem or knows how it could be fixed?

Chance Nguyen 09-12-2019 07:04 PM
Originally Posted by LeoNA (Post 1548688)
With a stand alone you don't need the idle valve. The ISCV is more adequate. Cut out a block off gasket for the IV.
Sorry. I have may been using the incorrect terms.its actually my iscv that I've been having problems with. I actually already have a dead end gasket on my idle valve or air valve (the part with the wax plug that closes and opens due to coolant temp changes) this particular problem has occured before and after me installing the dead end gasket.

hks_kansei 09-12-2019 08:05 PM
Have you pulled the valve off and cleaned it out?
it may just be as simple as it having some crap in there causing it to slightly jam.

Chance Nguyen 09-12-2019 09:36 PM
Originally Posted by hks_kansei (Post 1548724)
Have you pulled the valve off and cleaned it out?
it may just be as simple as it having some crap in there causing it to slightly jam.
I have cleaned it with some carb cleaner. I need went as far as replacing it. I'll try to take it off later, hook up to tunerstudio, and pulse it while spraying it with carb cleaner.

hks_kansei 09-12-2019 09:56 PM
I cant remember if they have any greased/oiled parts inside, since I haven't had one apart before.
I would assume though that it's at least got a film of thin oil there to lower friction of moving parts.

But bear in mind that carb cleaner will have taken off any oil/grease, so can actually increase the chance of sticking if you dont re-oil etc.



But yeah, pulsing it and confirming that it moves freely is a good idea.

Chance Nguyen 09-13-2019 12:13 AM
Originally Posted by hks_kansei (Post 1548736)
I cant remember if they have any greased/oiled parts inside, since I haven't had one apart before.
I would assume though that it's at least got a film of thin oil there to lower friction of moving parts.

But bear in mind that carb cleaner will have taken off any oil/grease, so can actually increase the chance of sticking if you dont re-oil etc.



But yeah, pulsing it and confirming that it moves freely is a good idea.
What kind of oil is safe to spray into it? Lithium grease? Silicone?

hks_kansei 09-13-2019 01:24 AM
You'll need to check the OEM manual and see if it lists a spec.
Or if it needs to be oiled at all.

As I said, i've not had one apart, but normally stuff like that has some kind of lubrication.


If I had to suggest anything, it would be something thin and with low stiction, that also doesn't dry out and thicken.


On things like SU carbs where you need the piston to freely slide up and down you usually just use a smear of light engine oil, or sewing machine oil, Or even ATF.
If it needs anything, it wont be much, just a few drops really to slick up the moving parts.

LeoNA 09-13-2019 05:07 PM
Why is your idle frequency set at 92hz? Most run 383hz. Also your MAT air density is fairly radical. I run 100% at 70 and down to 97% at 200.

Chance Nguyen 09-13-2019 06:45 PM
Originally Posted by LeoNA (Post 1548854)
Why is your idle frequency set at 92hz? Most run 383hz. Also your MAT air density is fairly radical. I run 100% at 70 and down to 97% at 200.
I'm assuming you changed your mat air density from basemap? I don't think I changed it from basemap. I'll try adjusting that. Also. Ive been told it runs around 300-400 hz but I keep getting this weird click and jumpy rpms. 92hz is the only one I've been able to get it to move fully though it's range without clicking.
https://cimg6.ibsrv.net/gimg/www.mia...9644ab5e66.jpg
is this close to what you're explaining? More linear?
Edit: I did some reading. I should set it to 100 straight across, tune, THEN adjust the mat density correction.

Chance Nguyen 09-14-2019 03:51 PM
Originally Posted by Chance Nguyen (Post 1548860)
I'm assuming you changed your mat air density from basemap? I don't think I changed it from basemap. I'll try adjusting that. Also. Ive been told it runs around 300-400 hz but I keep getting this weird click and jumpy rpms. 92hz is the only one I've been able to get it to move fully though it's range without clicking.
https://cimg6.ibsrv.net/gimg/www.mia...9644ab5e66.jpg
is this close to what you're explaining? More linear?
Nvm I did some reading. I should set at 100 across, tune, THEN adjust mat correction.

LeoNA 09-14-2019 07:40 PM
Sorry about the tardy response. I had to decrease the correction because of heat soak of the IAT.



https://cimg4.ibsrv.net/gimg/www.mia...eea2a74fe.jpeg

Chance Nguyen 09-17-2019 12:25 AM
Originally Posted by LeoNA (Post 1548931)
Sorry about the tardy response. I had to decrease the correction because of heat soak of the IAT.



https://cimg4.ibsrv.net/gimg/www.mia...eea2a74fe.jpeg
Ahhh, this fixed my "lean afrs when its hot" problem. iscv problem still occurs. I have a second hand ecu. Is there any process that needs to be taken such as installing a transistor or diode when using a stepper motor or a different iscv?

venetox 10-29-2019 09:12 PM
If you are having clicking issues and etc when on the correct higher frequency you likely have no flyback diode in the circuit.

I had this for a long time and was wondering why my ISCV range was so low and irratic.

Put a flyback diode in. (diode in parallel with ISCV circuit but in backwards so it shorts the flyback voltage out)

This should resolve most of your issues.


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