No fast idle on 90-93 MSI - Miata Turbo Forum - Boost cars, acquire cats.

Welcome to Miataturbo.net   Members
 


MEGAsquirt A place to collectively sort out this megasquirt gizmo

Reply
 
 
 
LinkBack Thread Tools
Old 05-06-2012, 08:57 PM   #1
Junior Member
Thread Starter
 
Join Date: Mar 2012
Location: Portugal
Posts: 199
Total Cats: -12
Default No fast idle on 90-93 MSI

Hello!

I've been tuning the hell out of my Megasquirt lately, and I've got the car to run smooth as hell. I'm a happy camper! But there's still one small niggle to be solved.

I searched on this matter here, and on other forums, to no avail. I can't figure out why my car isn't fast idling. I've double and triple-checked all the configurations and nothing seems wrong.

These past few days I've been hand tuning the VE Table, and some other things. However, due to some unforeseen factor (could be the cold weather, or something I messed up while tuning) the car now idles very rougly right after startup. I had this happen the first times I started the Megasquirt, but then it was pretty normal so I didn't pay much attention to it. Now it is back. When I turn the car on, the engine starts then the idle oscilates heavily, and almost (or sometimes even) stalls. I need to put my foot on the accelerator, to keep the revs at 1xxx rpm for one or two seconds, and it stabilizes, but when it does, it goes around 950 RPM which I reckon is the slow idle.

Also, it only does it when cold. While hot, it starts and idles just as it should! And when cold, the idle works fine, only it slow idles. The stumbling and stalling is only on startup.

My fast idle is set for 1400 RPM, and since this is a '91 Miata, it has no fast idle valve, just the regular ol' PWM idle valve. Could it be a problem with that bypass valve on the side of the inlet manifold? Still, this doesn't explain why it doesn't fast idle. It must be a tuning issue.

Anyone that can shed a light on this matter, will be greatly appreciated!


Idle settings:
Attached Thumbnails
No fast idle on 90-93 MSI-fastidleproblems.png  
ThunderFox is offline   Reply With Quote
Old 05-07-2012, 12:12 PM   #2
Supporting Vendor
 
Matt Cramer's Avatar
 
Join Date: Sep 2006
Posts: 2,266
Total Cats: 51
Default

Exactly what ECU do you have? You said you had a DIYPNP, which is MS2 based, but the screen shot you posted is for an MS1.
Matt Cramer is offline   Reply With Quote
Old 05-07-2012, 12:16 PM   #3
Junior Member
Thread Starter
 
Join Date: Mar 2012
Location: Portugal
Posts: 199
Total Cats: -12
Default

It's one of Brain's DIYPNP MS1 units, not a recent DIYPNP
ThunderFox is offline   Reply With Quote
Old 05-07-2012, 12:17 PM   #4
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 72,908
Total Cats: 1,793
Default

Quote:
Originally Posted by ThunderFox View Post
It's one of Brain's DIYPNP MS1 units, not a recent DIYPNP

so it's a MS1 cpu on a v3.0 board and a hand built PNP harness?
Braineack is offline   Reply With Quote
Old 05-07-2012, 12:18 PM   #5
Junior Member
Thread Starter
 
Join Date: Mar 2012
Location: Portugal
Posts: 199
Total Cats: -12
Default

Yeah that's it! Standalone version.
ThunderFox is offline   Reply With Quote
Old 07-17-2012, 11:44 AM   #6
Junior Member
Thread Starter
 
Join Date: Mar 2012
Location: Portugal
Posts: 199
Total Cats: -12
Default

I have been fiddling with the idle settings quite a bit, but I have gotten nowhere...

It just struck me that I must have something misconfigured, or my idle valve is bad. I fiddled around with the settings on a friend's NA who has a BP-ZE engine, and the changes in the settings resulted in the idle behaviour becoming much different. I see no changes in my car.

I also recall my car used to stall with the OEM ECU. It doesn't now, but it does have that erratic behaviour on engine start.

I'm currently back to the default settings that come with the MSPNP_90-93_NoAFM default tune. Is there any way I can test the idle valve?
ThunderFox is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Back to Stock Part Out!! Turbo Parts, MS2 Enhanced 01-05, Suspension, and MOAR! StratoBlue1109 Miata parts for sale/trade 16 10-02-2015 10:39 AM
Time to start learning and play with tuning The Gleas MEGAsquirt 3 10-01-2015 10:30 AM
Are my coils failing? viriiguy General Miata Chat 5 09-28-2015 08:39 PM


Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 01:03 PM.