couple of AE questions

[Yves]

I have a SBC engine on ITB's and ms3 sequential.

So far I have not had much succes with a correct AE setting.

Initially I only used tps based AE (time based) What I saw was much the same the problem with tuning the VE tables on map only. AE wasn't cutting in at low throttle openings, causing a severe lean condition which was mostly there when coming of decel and opening the throttle a little to accelerate again. I was experiencing heavy backfiring through the exhaust.
I then tried a combination of mapdot ae with tpsdot ae (50% map/50% tp) and tried to get the correct numbers for the amount of fuel to be injected. This certainly cured the backfiring (farting) in the exhaust and prevented the engine from really leaning out (+19:1) on small throttle openings.

The issue was however that the ae came in too late, still causing a lean condition upon acceleration. I tried setting the mapdot and tpsdot thresholds as low as possible but even so, I'm still experiencing the problem.

I think this is because of the massive amount of air going into the engine when cracking the engine slightly.

Would the accel-pump enrichtment option be better suited to combat this ?

[kaeman]

I was having ae issues with my itb small block chevy, I ended up turning off the accel enrichment and fine tuned the ve tables, the problem I was having was stumble on hard acceleration from idle, I found out that I was getting too much fuel, turned off the enrichment by setting the tps value to something like 1% at 240, 2% at 480, 3 % at 850 and 4% at 1200 tpsdot. then the accel enrich almost never triggered, what I found was that my fuel tables in the low rpm high load areas were way too rich, auto-tune kept adding fuel to a rich misfire that showed up as a lean spike when first stabbing the throttle. when I got the fuel removed from the ve table in those areas the engine accelerated great and without the lean spike in the o2 sensor readings.

[Yves]

The farting was certainly not a rich misfire problem.

[turbo conversion]

Would the accel-pump enrichtment option be better suited to combat this ?


Give it a try and see.

David

[Paul_VR6]

I have had good luck with the accel pump option on larger itbs.

[Yves]

does that react faster in use ?

[turbo conversion]

does that react faster in use ?

Not sure, I am using an older firmware that does not have time based option.

David

[Rick Finsta]

You can also try the WOT as percent TPS table and see if that helps?

[eekoog]

Hello Yves,

Have you solved your problem ? Cause i am having the exact same problem with a rotary engine with very short intake on ITBs.
Please if you got it solved, please answer me cause i have been fighting for month with this thing...

Vous pouvez m'écrire en français, je suis basé à Lyon.

Merci merci merci

Maxime

[whittlebeast]

Eekoog



Andy

[whittlebeast]

see http://www.nbs-stl.com/CrxTypeR/3%20Sec ... ocross.png

The difference between the Duty Cycle Base and Duty Cycle1 on the second trace is the AE

The spikes at the bottom at the cylinder one at TDC to give me an idea of the number of ignition events that the AE is active. That data is taken at 100 samples per sec.

Andy

[Yves]

Hello Yves,

Have you solved your problem ? Cause i am having the exact same problem with a rotary engine with very short intake on ITBs.
Please if you got it solved, please answer me cause i have been fighting for month with this thing...

Vous pouvez m'écrire en français, je suis basé à Lyon.

Merci merci merci

Maxime

Maxime,

This is already a while back.

Under control is not the word actually. It's better, but not where I would like it. I think the backfiring through the exhaust is mainly caused by a very high vacuum on decel sucking off all the wall fuel which doesn't burn and subsequently burns in the exhaust when cracking the throttles open a bit. I first just activated the EAE which helped some but didn't totally cure it. I now have set the steps of my IAC valve to a minimum of 5 as to allow some air to get in there to reduce the vacuum a bit. May need to fine tune that though.

I also have a lot of AE tuned in at higher dot. I have less peaks at serious acceleration. Still get lean spikes on small throttle openings, especially after coming from a decel.

[Yves]

see http://www.nbs-stl.com/CrxTypeR/3%20Sec ... ocross.png

The difference between the Duty Cycle Base and Duty Cycle1 on the second trace is the AE

The spikes at the bottom at the cylinder one at TDC to give me an idea of the number of ignition events that the AE is active. That data is taken at 100 samples per sec.

Andy

I don't see any field that allows me to display duty cycle base nor ignition events. Maybe you can explain this a little ?

[whittlebeast]

To get Duty Cycle Base, you need to log Fuel: Accel enrich

then you use the formula

100*[Duty Cycle1]/[Fuel: Accel enrich]

Regarding TDC, you open your tuner studio project, then under <File> <Vehicle Properties> <Project Properties> <Settings> <Internal_Log_Fields> <activated>

Now you will get the ability to log all sorts of new things.

Pick next_spark.tooth as a logged field

now create a new field in MLV

TDC

and define it with the formula

[next_spark.tooth]>17?1:0

I realize it really is not TDC but work with me here... Note that it only works at high data rates like 100 to 350 samples per sec. Also note that these new exposed fields are used by the developers to debug SW and are all totally undocumented. They can change at any time as what they do or mean based on what the developers are working on in the code. Keep in mind that you don't have griping rights if some field you are playing with changes logic or even disappears.

Have fun tuning.

Andy

[Yves]

What's the 17?1:0

I just read your thread on mlv datalogging. Great thinking there, but I need to let some of the things sink in.
Did you ever wonder if a scatterplot with a fourth field would be worth it (3D ? )

[whittlebeast]

That is an if statement in mega log viewer that may change with your ignition setup

[Yves]

That is an if statement in mega log viewer that may change with your ignition setup

Ok, but in that case what does 17 and 1 refer to ?

[Yves]

see http://www.nbs-stl.com/CrxTypeR/3%20Sec ... ocross.png

The difference between the Duty Cycle Base and Duty Cycle1 on the second trace is the AE

The spikes at the bottom at the cylinder one at TDC to give me an idea of the number of ignition events that the AE is active. That data is taken at 100 samples per sec.

Andy

Andy,

Did some evaluations. Thanks for this. This does seem to be meaningful. I'm going to try out some settings.

[Yves]

For some reason I don't seem to be able to log the next_spark.tooth...

[whittlebeast]

What code version?