New to me Miata Tuning Issues
03-15-2023, 01:27 AM
#1
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New to me Miata Tuning Issues
Hello all, I just purchased a 94 Miata that appears to have some tuning issues. Below are the car details.
1994 Miata:
JRSC MP45
AEM Wideband
MSPNP2 Green Mobo
So now onto the issues, the vehicle doesn't cold start without the having to use throttle until it warms up and can hold an idle. The idle oscillates a lot when it's not warm. I have done some data logging and will attach the tune that came on the car. I found another tune on a very similar vehicle (same S/C, both had MSPNP2 and same year) that someone uploaded on this site that I also tried but it still wouldn't start and stay running without throttle. As you can tell by reading this I am a total noob when it comes to tuning. I purchased someone else's project and am stumped on this issue. I attached two logs, one with me just trying to crank over the vehicle without throttle and the other with me driving (wondering if this is maybe a vacuum leak or something). I tried testing for the vacuum leak with throttle body cleaner and didn't find anything (could try again if people think this is it). I would really appreciate it if someone could look over my current tune and see if anything looks really far off or setup improperly. Thank you for your time and let me know if there's anything other information I can pull together to help diagnose.
1994 Miata:
JRSC MP45
AEM Wideband
MSPNP2 Green Mobo
So now onto the issues, the vehicle doesn't cold start without the having to use throttle until it warms up and can hold an idle. The idle oscillates a lot when it's not warm. I have done some data logging and will attach the tune that came on the car. I found another tune on a very similar vehicle (same S/C, both had MSPNP2 and same year) that someone uploaded on this site that I also tried but it still wouldn't start and stay running without throttle. As you can tell by reading this I am a total noob when it comes to tuning. I purchased someone else's project and am stumped on this issue. I attached two logs, one with me just trying to crank over the vehicle without throttle and the other with me driving (wondering if this is maybe a vacuum leak or something). I tried testing for the vacuum leak with throttle body cleaner and didn't find anything (could try again if people think this is it). I would really appreciate it if someone could look over my current tune and see if anything looks really far off or setup improperly. Thank you for your time and let me know if there's anything other information I can pull together to help diagnose.
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03-22-2023, 01:29 PM
#2
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Join Date: Jun 2005
Location: WA
Posts: 504
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I'm fairly new to this but just taking a quick I see some things that could be an issue.
According to log your idle control valve closes as soon as the car catches and that kills the engine.
In closed loop idle control try changing crank to run taper to 5-7seconds and see if that helps and your idle valve open duty % seems way too low. It's at ~71 during cranking but your max is at 23.1 for idling. You can try disabling closed loop all together to check.
Try that and see if that helps.
According to log your idle control valve closes as soon as the car catches and that kills the engine.
In closed loop idle control try changing crank to run taper to 5-7seconds and see if that helps and your idle valve open duty % seems way too low. It's at ~71 during cranking but your max is at 23.1 for idling. You can try disabling closed loop all together to check.
Try that and see if that helps.
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