DBW idle control, rpm dips below idle speed on transit to idle

Questions about the Elite Series ECU's? Ask here.
SONofSUN
Posts: 74
Joined: Mon Jan 27, 2014 5:32 am

DBW idle control, rpm dips below idle speed on transit to idle

Postby SONofSUN » Sun Dec 10, 2017 10:21 pm

LS3 DBW throttle
Elite 2500
Plug in harness

When It transits from load to idle speed, it momentarily drops idle below idle speed than it picks up. Sometimes this causes the engine to stall. This happens more when engine is warm. Like while driving and coming to a stop, press clutch, idle dips to about 500 then picks up to idle speed 800.
I tried adjusting most parameters for idle control but could not solve it. Tried incrasing base idle but no change.

Any help is appreciated

User avatar
Mattias
Posts: 129
Joined: Sat Feb 21, 2015 6:57 pm
Location: Gothenburg, Sweden

Re: DBW idle control, rpm dips below idle speed on transit to idle

Postby Mattias » Mon Dec 11, 2017 12:36 am

Hi,

I had this issue also in the past, if I remember correctly deactivating decel cut for some reason solved it. So would be interesting if that is the case for you too.

My final solution was to set Idle Control Min Output to slightly below normal idle instead of zero. This kept the engine from stalling but still there seems to be some other setting or the controller itself that lets the idle output go to zero when engaging the clutch while decelerating to a stop.

Let us know if this works.

Br,
Mattias

SONofSUN
Posts: 74
Joined: Mon Jan 27, 2014 5:32 am

Re: DBW idle control, rpm dips below idle speed on transit to idle

Postby SONofSUN » Mon Dec 11, 2017 2:10 pm

Mattias wrote:Hi,

I had this issue also in the past, if I remember correctly deactivating decel cut for some reason solved it. So would be interesting if that is the case for you too.

My final solution was to set Idle Control Min Output to slightly below normal idle instead of zero. This kept the engine from stalling but still there seems to be some other setting or the controller itself that lets the idle output go to zero when engaging the clutch while decelerating to a stop.

Let us know if this works.

Br,
Mattias


I will try this and feedback
thanks,

User avatar
HaltechMatthew
Haltech Staff
Posts: 3304
Joined: Tue Feb 07, 2012 12:45 pm
Location: Sydney, Australia
Contact:

Re: DBW idle control, rpm dips below idle speed on transit to idle

Postby HaltechMatthew » Mon Dec 11, 2017 2:44 pm

Too lean in the areas just above idle in the decel areas.

As a test just set an overall trim maybe 10 or 20% richer and see if it still occurs.

SONofSUN
Posts: 74
Joined: Mon Jan 27, 2014 5:32 am

Re: DBW idle control, rpm dips below idle speed on transit to idle

Postby SONofSUN » Mon Dec 11, 2017 11:05 pm

HaltechMatthew wrote:Too lean in the areas just above idle in the decel areas.

As a test just set an overall trim maybe 10 or 20% richer and see if it still occurs.


Thanks Matt. I will try this also.

SONofSUN
Posts: 74
Joined: Mon Jan 27, 2014 5:32 am

Re: DBW idle control, rpm dips below idle speed on transit to idle

Postby SONofSUN » Fri Dec 15, 2017 5:40 am

Mattias wrote:Hi,

I had this issue also in the past, if I remember correctly deactivating decel cut for some reason solved it. So would be interesting if that is the case for you too.

My final solution was to set Idle Control Min Output to slightly below normal idle instead of zero. This kept the engine from stalling but still there seems to be some other setting or the controller itself that lets the idle output go to zero when engaging the clutch while decelerating to a stop.

Let us know if this works.

Br,
Mattias


Hi

Tried this,
Decl cut deactivated. still the same issue

SONofSUN
Posts: 74
Joined: Mon Jan 27, 2014 5:32 am

Re: DBW idle control, rpm dips below idle speed on transit to idle

Postby SONofSUN » Fri Dec 15, 2017 5:59 am

HaltechMatthew wrote:Too lean in the areas just above idle in the decel areas.

As a test just set an overall trim maybe 10 or 20% richer and see if it still occurs.


I tried this. I made it up to 0.88 Lambda, no effect.

User avatar
blakebonkofsky
Posts: 365
Joined: Sun Aug 02, 2015 2:58 am

Re: DBW idle control, rpm dips below idle speed on transit to idle

Postby blakebonkofsky » Fri Dec 15, 2017 8:37 am

Can you post your map so we can look at it? Sometimes it's a simple setting that is overlooked and it helps to have a second set of eyes go over it.

User avatar
Mattias
Posts: 129
Joined: Sat Feb 21, 2015 6:57 pm
Location: Gothenburg, Sweden

Re: DBW idle control, rpm dips below idle speed on transit to idle

Postby Mattias » Fri Dec 15, 2017 5:32 pm

SONofSUN wrote:
Mattias wrote:Hi,

I had this issue also in the past, if I remember correctly deactivating decel cut for some reason solved it. So would be interesting if that is the case for you too.

My final solution was to set Idle Control Min Output to slightly below normal idle instead of zero. This kept the engine from stalling but still there seems to be some other setting or the controller itself that lets the idle output go to zero when engaging the clutch while decelerating to a stop.

Let us know if this works.

Br,
Mattias


Hi

Tried this,
Decl cut deactivated. still the same issue


Did you try the Min Output?

SONofSUN
Posts: 74
Joined: Mon Jan 27, 2014 5:32 am

Re: DBW idle control, rpm dips below idle speed on transit to idle

Postby SONofSUN » Sun Dec 17, 2017 1:56 am

Mattias wrote:
SONofSUN wrote:
Mattias wrote:Hi,

I had this issue also in the past, if I remember correctly deactivating decel cut for some reason solved it. So would be interesting if that is the case for you too.

My final solution was to set Idle Control Min Output to slightly below normal idle instead of zero. This kept the engine from stalling but still there seems to be some other setting or the controller itself that lets the idle output go to zero when engaging the clutch while decelerating to a stop.

Let us know if this works.

Br,
Mattias


Hi

Tried this,
Decl cut deactivated. still the same issue


Did you try the Min Output?


Yes tried adjusting Min Output. it is better now not stalling but still dips on decl.

SONofSUN
Posts: 74
Joined: Mon Jan 27, 2014 5:32 am

Re: DBW idle control, rpm dips below idle speed on transit to idle

Postby SONofSUN » Sun Dec 17, 2017 2:04 am

[quote="blakebonkofsky"]Can you post your map so we can look at it? Sometimes it's a simple setting that is overlooked and it helps to have a second set of eyes go over it.[/quote]
Map attached
appreciate all comments
Attachments
LS3_6532A_DBW.zip
(41.92 KiB) Downloaded 93 times

User avatar
Mattias
Posts: 129
Joined: Sat Feb 21, 2015 6:57 pm
Location: Gothenburg, Sweden

Re: DBW idle control, rpm dips below idle speed on transit to idle

Postby Mattias » Sun Dec 17, 2017 2:26 am

Maybe Matt can confirm if the DBW always goes to "Min output" while engine braking to a stop/on decel. I guess it would work better if it went to idle base output when below decel min speed setting.

User avatar
Mattias
Posts: 129
Joined: Sat Feb 21, 2015 6:57 pm
Location: Gothenburg, Sweden

Re: DBW idle control, rpm dips below idle speed on transit to idle

Postby Mattias » Sun Dec 17, 2017 2:43 am

SONofSUN wrote:
blakebonkofsky wrote:Can you post your map so we can look at it? Sometimes it's a simple setting that is overlooked and it helps to have a second set of eyes go over it.

Map attached
appreciate all comments


You could try to add an axis to the Min Output, clutch or speed. So you can have a higher value without messing up the idle in neutral.

User avatar
HaltechMatthew
Haltech Staff
Posts: 3304
Joined: Tue Feb 07, 2012 12:45 pm
Location: Sydney, Australia
Contact:

Re: DBW idle control, rpm dips below idle speed on transit to idle

Postby HaltechMatthew » Mon Dec 18, 2017 4:02 pm

Nope. Goes to Base Duty + Long Term Correction + Decel Offset when you lift off the throttle.

If it is not a fuel issue as we normally see with LS engines, it perhaps needs more Decel Offset and a shorter time around 0.5s

User avatar
blakebonkofsky
Posts: 365
Joined: Sun Aug 02, 2015 2:58 am

Re: DBW idle control, rpm dips below idle speed on transit to idle

Postby blakebonkofsky » Mon Dec 18, 2017 5:08 pm

Honestly, I'd go back over all of your idle set points. You've got 90-95% base output at operating temp, with a minimum output of 80%, but then the long term trim is at -114%. I would think there is no way that an LS3 throttle body should need to be open that much to get the engine to idle, and the long term trim kinda confirms that. It appears as if the LTT is trying to get the idle speed down, but the minimum output of 80% is preventing it from actually closing enough. Therefore, the LTT numbers are wayyyyy too high. If it were me, I would reset the LTT to zero, reset the minimum output to zero, and start from scratch on your Base - Closed Loop table.

Do you have a log available of the decel event or even just idle? I'd log RPM, idle control output, idle control ignition correct, and throttle position at minimum.


Return to “Elite Series”

Who is online

Users browsing this forum: BIRDMAN and 3 guests