High Idle after IACV adjustment
#1
93 NA MSPNP2 Crazy IAC settings
93' NA running MSPNP2.
The car starts and idles very well, but cold starts I'm having some trouble. Takes 2 or three attempts at cranking to catch, even with my IAC at full open. Current settings are Normal Mode, 313 Hz because that keeps the valve from clicking and squealing (I know it's usually 200 Hz). Idle close 26%, Idle open 62%. Well, I took my IAC off and recorded what's happening during Idle Valve test mode. It's all unusual.
IAC settings
Mode:Normal (0%=Off)
Testing Range 1%open -> 25%closed and then 26%closed -> 62%open the wrong way?
Freq 313Hz
It looks like this whole time, I was using just that sliver of open (when the valve continues past closed and ends up opening slightly). That would explain why I can't get more air; anything beyond 62% doesn't open anymore. So, I tried to set my open setting to 1% and closed to 25% (because that's what it is doing), and it just goes crazy when CLi engages. It jumps up to 1800 which cancels Cli, and then idles fine, and repeat. I have my initial values table in the high 20s, but it's like megasquirt keeps trying to slam the IAC open even though 25%= closed.
SO, I try different settings
Mode: Inverted (100%=Off)
Testing Range 81%open-99%closed
Freq 313Hz
This seemed better, but just has the valve clicking and squealing no matter what frequency.
I just don't understand why my valve isn't running in the correct 25-70 range. Like I said, It idles and starts great MOST of the time. But below 32 it struggles. I guess I could open the idle air screw a bit to help with cold starts and then shut the IAC a bit. Just seems plain wrong that i'm only using 1/4 of the IAC between 26 and 62. Attaching a video for more clarity. I put the % range in the text (it will change when we get to a close/open point)
https://imgur.com/a/bMAz7XY
The car starts and idles very well, but cold starts I'm having some trouble. Takes 2 or three attempts at cranking to catch, even with my IAC at full open. Current settings are Normal Mode, 313 Hz because that keeps the valve from clicking and squealing (I know it's usually 200 Hz). Idle close 26%, Idle open 62%. Well, I took my IAC off and recorded what's happening during Idle Valve test mode. It's all unusual.
IAC settings
Mode:Normal (0%=Off)
Testing Range 1%open -> 25%closed and then 26%closed -> 62%open the wrong way?
Freq 313Hz
It looks like this whole time, I was using just that sliver of open (when the valve continues past closed and ends up opening slightly). That would explain why I can't get more air; anything beyond 62% doesn't open anymore. So, I tried to set my open setting to 1% and closed to 25% (because that's what it is doing), and it just goes crazy when CLi engages. It jumps up to 1800 which cancels Cli, and then idles fine, and repeat. I have my initial values table in the high 20s, but it's like megasquirt keeps trying to slam the IAC open even though 25%= closed.
SO, I try different settings
Mode: Inverted (100%=Off)
Testing Range 81%open-99%closed
Freq 313Hz
This seemed better, but just has the valve clicking and squealing no matter what frequency.
I just don't understand why my valve isn't running in the correct 25-70 range. Like I said, It idles and starts great MOST of the time. But below 32 it struggles. I guess I could open the idle air screw a bit to help with cold starts and then shut the IAC a bit. Just seems plain wrong that i'm only using 1/4 of the IAC between 26 and 62. Attaching a video for more clarity. I put the % range in the text (it will change when we get to a close/open point)
https://imgur.com/a/bMAz7XY
Last edited by popupboost; 01-08-2022 at 01:07 PM. Reason: Clarified problem
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