Hot start throttle hang - Miata Turbo Forum - Boost cars, acquire cats.

MEGAsquirt A place to collectively sort out this megasquirt gizmo

Hot start throttle hang

Old 02-12-2018, 02:21 PM
  #1  
Elite Member
Thread Starter
 
Join Date: Sep 2015
Location: San Jose, CA
Posts: 1,531
Total Cats: 103
Default Hot start throttle hang

hi guys. Whenever I hot start my car, the throttle always seems to hang for 1 sec when shifting. It wont do it if the car is warmed up from a cold start. Ideas?
MiataMan00 is offline  
Old 02-13-2018, 09:26 AM
  #2  
Supporting Vendor
 
Matt Cramer's Avatar
 
Join Date: Sep 2006
Posts: 2,329
Total Cats: 62
Default

Try less crank to run taper time.
__________________
Matt Cramer
www.diyautotune.com
Matt Cramer is offline  
Old 02-13-2018, 12:22 PM
  #3  
Elite Member
Thread Starter
 
Join Date: Sep 2015
Location: San Jose, CA
Posts: 1,531
Total Cats: 103
Default

Ok ill try that. Thanks Matt.
MiataMan00 is offline  
Old 03-20-2018, 12:58 PM
  #4  
Elite Member
Thread Starter
 
Join Date: Sep 2015
Location: San Jose, CA
Posts: 1,531
Total Cats: 103
Default

Update. That helped with inital startup. But when I am driving the car there is still throttle hang after a hot start. This started happening after the skunk 2 tb install. And yes, I already re-drilled the throttle spring hole.
MiataMan00 is offline  
Old 03-20-2018, 03:03 PM
  #5  
Moderator
iTrader: (12)
 
sixshooter's Avatar
 
Join Date: Nov 2008
Location: Tampa, Florida
Posts: 17,601
Total Cats: 2,006
Default

Originally Posted by MiataMan00 View Post
Update. That helped with inital startup. But when I am driving the car there is still throttle hang after a hot start. This started happening after the skunk 2 tb install. And yes, I already re-drilled the throttle spring hole.
Drill it again. Drill it harder. Drill it with fire!

Okay, maybe don't drill it again. Ensure your throttle cable is not kinky and that there is nothing in the way of wiring harnesses or insulation interfering with the cable inside the firewall.
sixshooter is offline  
Old 03-20-2018, 04:57 PM
  #6  
Elite Member
iTrader: (17)
 
Join Date: Aug 2007
Location: Fort Myers, FL
Posts: 2,877
Total Cats: 162
Default

Wouldn't decreasing IAC initial values table in affected cells help this? Presumably the top row where you're highest CLT/IAT numbers are.

*Sorry if that's a dumb suggestion. I suck at idle tuning and I'm still trying to grasp how everything works together.*
pdexta is offline  
Old 03-20-2018, 05:18 PM
  #7  
Elite Member
Thread Starter
 
Join Date: Sep 2015
Location: San Jose, CA
Posts: 1,531
Total Cats: 103
Default

Originally Posted by sixshooter View Post
Drill it again. Drill it harder. Drill it with fire!

Okay, maybe don't drill it again. Ensure your throttle cable is not kinky and that there is nothing in the way of wiring harnesses or insulation interfering with the cable inside the firewall.
Itís not that because it only does it after hot starts. Running it from a cold start itís fine.
Originally Posted by pdexta View Post
Wouldn't decreasing IAC initial values table in affected cells help this? Presumably the top row where you're highest CLT/IAT numbers are.

*Sorry if that's a dumb suggestion. I suck at idle tuning and I'm still trying to grasp how everything works together.*
wouldnt help. Itís not an idle thing. It does it between shifts.
MiataMan00 is offline  
Old 03-20-2018, 06:03 PM
  #8  
Junior Member
 
Join Date: May 2007
Location: Atlanta
Posts: 499
Total Cats: 64
Default

Dashpot adder too high?
gooflophaze is offline  
Old 03-22-2018, 04:15 PM
  #9  
Elite Member
Thread Starter
 
Join Date: Sep 2015
Location: San Jose, CA
Posts: 1,531
Total Cats: 103
Default

I dont think so because the throttle dips when entering idle. Of anything I need to raise it
MiataMan00 is offline  
Old 03-22-2018, 04:16 PM
  #10  
Elite Member
Thread Starter
 
Join Date: Sep 2015
Location: San Jose, CA
Posts: 1,531
Total Cats: 103
Default

I dont think so because the throttle dips when entering idle. If anything I need to raise it.
MiataMan00 is offline  
Old 03-22-2018, 04:55 PM
  #11  
Supporting Vendor
iTrader: (31)
 
Savington's Avatar
 
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 14,860
Total Cats: 1,702
Default

$20 says a datalog will show it's not actually in closed-loop idle mode when it hangs. The valve hangs open because the RPM is outside the bounds where CL idle can activate, and so it hangs there forever. Blip the throttle and the revs will drop on the way down, CL will activate, and it will come down to a normal idle.

Reduce the max idle DC% or reduce the hot idle initial duty cycle.
__________________
Trackspeed Engineering
High-Performance Turbo Specialists - Sunnyvale, CA - 650-701-7223 - Email us!
Originally Posted by codrus View Post
Basically I've come over to the camp of "If something is a reliability problem on the track, just ask Andrew and do what he says".
Savington is offline  
Old 03-23-2018, 12:12 AM
  #12  
Elite Member
Thread Starter
 
Join Date: Sep 2015
Location: San Jose, CA
Posts: 1,531
Total Cats: 103
Default

It will come down to idle rpm every time. Its just when shifting, the RPMs dont drop when clutch is depressed. it hangs for .5-1 sec before dropping down. Its not an idle issue.

Last edited by MiataMan00; 04-26-2018 at 12:36 AM.
MiataMan00 is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
jpbro
General Miata Chat
9
07-05-2017 08:58 AM
rmcelwee
Insert BS here
43
12-22-2009 08:46 PM
Madboy
General Miata Chat
11
07-31-2009 05:21 PM
Saml01
MEGAsquirt
5
03-17-2009 01:01 PM
Arkmage
Local Meets, Events and Tech Days
7
08-07-2008 10:17 PM


Quick Reply: Hot start throttle hang


Archive Advertising Cookie Policy Privacy Statement Terms of Service

© 2018 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.