It is currently Tue Jul 16, 2019 2:11 am



Post new topic Reply to topic  [ 6 posts ] 
Author Message
 Post subject: Setting up ignition based idle control
PostPosted: Thu Jul 04, 2019 8:05 am 
Offline

Joined: Wed Jan 28, 2015 5:42 am
Posts: 64
ECU Model: S40 Pro
Distributor: Lotusbits
Firmware Version: 75
This may well be obvious to many on here, but it wasn't to me until I thought about it!

My idle control timing limit parameters were set at +25 degrees down to -15 degrees. The way the system works is to reduce timing if idle speed is too high, and increase it when too low. Timing at idle was originally set up at 10 degrees (on the main ignition map).

My particular requirement is to have decent control over idle in my automatic - in other words, so the idle control copes with the load on the engine when Drive is engaged. However similar issues may arise on a manual car with aircon and cooling fan loads at idle.

My car idled very poorly in general - lumpy, variable, and sometimes stalling. As suggested in the manual, I went in to reduce the ignition timing at idle in order to give the idle controller sufficient scope to increase timing to compensate for load, so I reduced it to 6 degrees which gave a steady idle speed (with idle control turned off) of 1200rpm vs the 1300+rpm I was seeing at the original setting of 10 degrees. Then I switched idle control back on and monitored the adjustments in timing being made by the ECU to control idle both in gear and in neutral. In gear, timing was being advanced to 15 degrees with relatively poor running, and in neutral it was very lumpy and variable with the timing dropping below -5 degrees. I then disabled idle control again and played about with ignition map settings to find out the effect of timing on idle speed. It turned out that idle speed started to reduce when the timing was increased above 10 degrees, with 10 degrees giving the maximum speed. Reducing timing, idle behaviour became erratic and lumpy when timing dropped below -5 degrees. There was therefore no point allowing the system to set timing outside these limits! Once these were set in the system, idle behaviour was transformed.

So, if you are using timing control of idle, my advice is to test idle behaviour first with different timing settings to find out the optimal maximum and minimum settings for your engine, and use these.

I don't think I now need an idle air control valve.


Top
 Profile  
 
 Post subject: Re: Setting up ignition based idle control
PostPosted: Thu Jul 04, 2019 3:28 pm 
Offline

Joined: Tue Aug 02, 2011 12:08 pm
Posts: 2987
Location: Norn Iron
ECU Model: No ECU
This is called tuning.


Top
 Profile  
 
 Post subject: Re: Setting up ignition based idle control
PostPosted: Thu Jul 04, 2019 4:05 pm 
Offline

Joined: Wed Jan 28, 2015 5:42 am
Posts: 64
ECU Model: S40 Pro
Distributor: Lotusbits
Firmware Version: 75
Yes, and this Forum is called "Tuning - tips and tricks"


Top
 Profile  
 
 Post subject: Re: Setting up ignition based idle control
PostPosted: Fri Jul 05, 2019 2:44 am 
Offline

Joined: Thu Jul 28, 2011 4:10 am
Posts: 928
ECU Model: S100 Pro
Distributor: None-Coil On Plug :)
I've said this before but get a wide band, you might start getting somewhere then


Top
 Profile  
 
 Post subject: Re: Setting up ignition based idle control
PostPosted: Fri Jul 05, 2019 1:36 pm 
Offline

Joined: Wed Jan 28, 2015 5:42 am
Posts: 64
ECU Model: S40 Pro
Distributor: Lotusbits
Firmware Version: 75
Rob Stevens wrote:
I've said this before but get a wide band, you might start getting somewhere then

I know I need to do that Rob, but until I do fit wideband (and I don't 100% have the confidence to do it myself) then I was very pleased with the improvement from the change I described. I felt it was worth posting as the DTA documentation only goes as far as advising that the butterfly is set so that slightly retarded (from optimal) idle timing gives the idle speed you need. Maybe it is too obvious to check the effects of timing on idle speed that I did, but if so I wonder why my engine was set up as it was. Anyway I posted in the hope that somebody would find it useful.

Cheers, Richard


Top
 Profile  
 
 Post subject: Re: Setting up ignition based idle control
PostPosted: Fri Jul 05, 2019 2:42 pm 
Offline

Joined: Tue Aug 02, 2011 12:08 pm
Posts: 2987
Location: Norn Iron
ECU Model: No ECU
you're trying to tune without a wideband ?

wow. one of the cheapest yet most important tools these days

it really does seem futile to attempt tuning without some means of reading mixtures, even more so for the inexperienced.

Get a wideband.


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 6 posts ] 

Who is online

Users browsing this forum: No registered users and 2 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
Theme designed by stylerbb.net © 2008
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group
All times are UTC - 5 hours