DIY PROM Do It Yourself PROM chip burning help. No PROM begging. No PROMs for sale. No commercial exchange. Not a referral service.

commanded idle speed/IAC question

Thread Tools
 
Search this Thread
 
Old 06-02-2005, 04:33 PM
  #1  
TGO Supporter

Thread Starter
iTrader: (1)
 
Ronny's Avatar
 
Join Date: Mar 2003
Location: wisconsin
Posts: 6,879
Likes: 0
Received 3 Likes on 3 Posts
commanded idle speed/IAC question

i set my commanded idle speed in tune to 700 as i could not get car to stable idle at 800. seemed to want to idle around 850-900. no help. IAC counts were coming and going with surguing resulting. seems this isue is not all that uncommon?

i attempted to remove IAC from issue by setting idle speed by throttle blade position and setting commanded way low to 600. this seemed to help stabilize idle somewhat. i think i have other issue affecting a pulsating idle(low BPW problem) as well.

now the Q is does setting commanded idle speed way low affect the A/F ratio at idle in CL? i am CL at idle. does the ECU command a leaner A/F at 600 than say 800 rpms idle speed? again assuming IAC counts are sitting at 0 even when engine idle pulsates.

ps. seems when OL and choke timed out(130-159F) the idle is super smooth at 750 !! CL invoke is obvious...
Old 06-04-2005, 10:19 AM
  #2  
Moderator

iTrader: (1)
 
RBob's Avatar
 
Join Date: Mar 2002
Location: Chasing Electrons
Posts: 18,432
Likes: 0
Received 225 Likes on 211 Posts
Car: check
Engine: check
Transmission: check
Re: commanded idle speed/IAC question

Originally posted by Ronny
i set my commanded idle speed in tune to 700 as i could not get car to stable idle at 800. seemed to want to idle around 850-900. no help. IAC counts were coming and going with surguing resulting. seems this isue is not all that uncommon?

i attempted to remove IAC from issue by setting idle speed by throttle blade position and setting commanded way low to 600. this seemed to help stabilize idle somewhat. i think i have other issue affecting a pulsating idle(low BPW problem) as well.

now the Q is does setting commanded idle speed way low affect the A/F ratio at idle in CL? i am CL at idle. does the ECU command a leaner A/F at 600 than say 800 rpms idle speed? again assuming IAC counts are sitting at 0 even when engine idle pulsates.

ps. seems when OL and choke timed out(130-159F) the idle is super smooth at 750 !! CL invoke is obvious...
No connection between IAC and closed loop fueling. To set the closed loop fueling for idle set the O2 window terms to match the open loop AFR as read by the WB.

Hook up the WB and just before it goes closed loop record the AFR as reported by the WB. Or just force open loop and do this at normal operating temperature.

Then go closed loop and adjust the O2 window to give the same (or close) idle AFR as reported by the WB. During idle both the normal O2 tables are used along with the idle offset term at $2F7.

It can also help closed loop hold tighter control over the idle AFR by setting $2FC to 255. Setting the idle proportional gain at $2F9 lower can also help.

RBob.
Old 06-06-2005, 10:36 AM
  #3  
TGO Supporter

Thread Starter
iTrader: (1)
 
Ronny's Avatar
 
Join Date: Mar 2003
Location: wisconsin
Posts: 6,879
Likes: 0
Received 3 Likes on 3 Posts
i have not yet leared hex editing. will look over the tunercat tables or contact them for an upgrade. thanks.
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
MustangBeater20
TBI
11
10-29-2022 09:20 PM
ezobens
DIY PROM
8
08-19-2015 10:29 PM
redmaroz
LTX and LSX
7
08-16-2015 11:40 PM
gta power
Exhaust
1
08-13-2015 06:15 AM



Quick Reply: commanded idle speed/IAC question



All times are GMT -5. The time now is 02:11 AM.