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[Ohio HD]

I have a question regarding the accelerator enrichment table in TTS. Since there is only a value based on the engine temperature, I'm wondering, does this table stay in effect when ever the throttle is moved further open? Or is it in effect only when coming off idle?

Thanks
Brian

[60FLH]

Whenever you accelerate, not just off idle- if you've v-tuned you can watch your histogram and up top it shows when AE and DE are active.

[Ohio HD]

I suspected that to be the case, but wasn't sure. I'll take a look at a couple of my recordings to  better understand how it's interacting.

Thanks

[FLTRI]

FWIW, I've found the accel enrichment table is much more sensitive with FBW bikes than cable bikes.
If you have a FBW bike the accel enrichment is probably set to high if the cams have been changed to ones with overlap.
Bob

[60FLH]

That's a very helpful tip I've seen you post before. Helped me cure a flat spot. Thanks!

[Ohio HD]

It is FBW Bob, I'm just trying to better understand how what I'll call the supporting tables work better. In other words if you have a very slight flat spot, or hesitation right off idle, this table may not be the best choice to use to try and correct that issue. Too much increase in fuel, you put it all across the board then.

Brian

[Buckeye_Tuning]

There are a couple things that can come into play with DBW.  REMOVE fuel from this table actually helps.  Running camtool is THE tool to use to find and fix the off idle flat spot thing.  Remember this... the blade inside of the TB is driven by a servo motor and NOT just from the throttle either.  It is all run from the ecm.  OK so far?

The ECM can make the blade do weird chit.  Of idle flats are usually caused by the throttle plate waving itself.  It is really weird to watch this!  You twist the throttle, the ECM starts to open the blade upon that command, but then AE wants it a certain amount of rich, and will close the blade while you are twisting the grip!  Then it will stop and go WHOA and open the blade again.  When you watch, you can see where the blade actually flutters open and close.

The cam tool can show this phenom.  While running cam tool.... you goose the throttle a little bit and watch the data points.  You can use Datamaster for this also.

I don't have any pics, but what you want up is TPS, MAP, and RPM.  On a well set throttle, those three will make like Teepees and each will be inside of itself and not touching each other.  WIth flutter, its easy to see, because they WILL touch each other or the tops of the Teepees become flat.

I usually remove the AC and LOOK for it, anymore.  I use the progressivity tables and AE to fix this.  Oh... and maxed out progressivity tables will AGGRAVATE this condition, not help.

[Mr. Wizard]

There are a couple things that can come into play with DBW.  REMOVE fuel from this table actually helps.  Running camtool is THE tool to use to find and fix the off idle flat spot thing.  Remember this... the blade inside of the TB is driven by a servo motor and NOT just from the throttle either.  It is all run from the ecm.  OK so far?

The ECM can make the blade do weird chit.  Of idle flats are usually caused by the throttle plate waving itself.  It is really weird to watch this!  You twist the throttle, the ECM starts to open the blade upon that command, but then AE wants it a certain amount of rich, and will close the blade while you are twisting the grip!  Then it will stop and go WHOA and open the blade again.  When you watch, you can see where the blade actually flutters open and close.

The cam tool can show this phenom.  While running cam tool.... you goose the throttle a little bit and watch the data points.  You can use Datamaster for this also.

I don't have any pics, but what you want up is TPS, MAP, and RPM.  On a well set throttle, those three will make like Teepees and each will be inside of itself and not touching each other.  WIth flutter, its easy to see, because they WILL touch each other or the tops of the Teepees become flat.

I usually remove the AC and LOOK for it, anymore.  I use the progressivity tables and AE to fix this.  Oh... and maxed out progressivity tables will AGGRAVATE this condition, not help.

This is what Buckeye is talking about...


The IVO found in the analyzer matches the IVO tool about 50% of the time. Depending on the build and the kPa at idle and just off idle.



The blip technique will not assist you in setting the IVC, sorry. Luckily there are only three set points. 3 is the most widely used, 2 is used about 30% of the time. If you have a HOT build then you may get to use 1, doubt it though.

The blip technique is for throttle response, immediate throttle response, without lag or stumble. It's not in the manual. It's not something that a person can put down as an instructive diagram or discussion. One must understand the proper table use which gives you a "feel" for what's going on with the motor.

Bob is spot on... most people "increase" by nature. Such as, if two aspirin are good, three is better. Not true when dealing with Delphi tables. Less can be more.

This must be done after several VTune sessions under 3500 RPM's or it will NOT work.

The tables I use for this while working with the blip and IVC are:
ARF/Lambda
AE
EGR
Timing at idle
Throttle Blade Control

Fine tuning of this I may use, but not always in addition to the above is:
Spark Temperature Correction
Closed Throttle Spark
Idle Spark Control Gain
Idle Spark Control Max

Visual representations include:
Throttle marking @ 10% and 20% with painters tape
Throttle body butterfly opening

The rest is "feel"

Once you have the data and sharp/equal blip points on the graph you must VTune again.

Now, not everyone will go this far and you really don't have to get this deep in tuning your motor but if you have stumble at off idle then you may want to use the same approach.

Bad blip between 10 and 20% quick throttle blip...



Good blip between 10 and 20% quick throttle blip...

[Buckeye_Tuning]

I was hoping you would jump in, Dave,  and...bring the screenshots.

I, for one, have found all of this to be a great tuning aid when dealing with flat spots down low.  It DOES work for me!!!

[Ohio HD]

Thanks for the info guys, it's not a bad off idle issue, just slight. Will see what I can do with it.

Brian

[Doc 1]

This is what Buckeye is talking about...


The IVO found in the analyzer matches the IVO tool about 50% of the time. Depending on the build and the kPa at idle and just off idle.



The blip technique will not assist you in setting the IVC, sorry. Luckily there are only three set points. 3 is the most widely used, 2 is used about 30% of the time. If you have a HOT build then you may get to use 1, doubt it though.

The blip technique is for throttle response, immediate throttle response, without lag or stumble. It's not in the manual. It's not something that a person can put down as an instructive diagram or discussion. One must understand the proper table use which gives you a "feel" for what's going on with the motor.

Bob is spot on... most people "increase" by nature. Such as, if two aspirin are good, three is better. Not true when dealing with Delphi tables. Less can be more.

This must be done after several VTune sessions under 3500 RPM's or it will NOT work.

The tables I use for this while working with the blip and IVC are:
ARF/Lambda
AE
EGR
Timing at idle
Throttle Blade Control

Fine tuning of this I may use, but not always in addition to the above is:
Spark Temperature Correction
Closed Throttle Spark
Idle Spark Control Gain
Idle Spark Control Max

Visual representations include:
Throttle marking @ 10% and 20% with painters tape
Throttle body butterfly opening

The rest is "feel"

Once you have the data and sharp/equal blip points on the graph you must VTune again.

Now, not everyone will go this far and you really don't have to get this deep in tuning your motor but if you have stumble at off idle then you may want to use the same approach.

Bad blip between 10 and 20% quick throttle blip...



Good blip between 10 and 20% quick throttle blip...

Or you might just tune the VE tables at 750 rpm off idle and get all the hesitation out....

[Mr. Wizard]

Told ya... an internet guru can't ride that low. 

Hope you are back to your old rat killings and feel better Doc

[FLTRI]

Simply put, once all the appropriate VEs are calibrated properly my rule of thumb for AE:
Reduce entire table by 10-15% for mild cam change. (Ie: TW26, SE204, etc)
Reduce 15-40% for higher overlap cams. (Ie: TW9F, TR662, etc)

Bob

[Ohio HD]

Good info Bob, thanks.

[Mr. Wizard]

Exactly...

Bottom line. Reduce the AE until you have stumble issues then work your way up.

Less is more.