DFCO never enabled on C5 Corvette ?

[Jochen]

One question about DFCO and the Table "DFCO Enable vs. RPM"

The definition says "Trottle position must be below this value".

The table in my PCM states values between 0.00 and 1.00 (see attached jpg file). But my TPS never goes to such a low value. That would mean my DFCO is NEVER enabled, right ?
When i change now this numbers to higer values, lets says all over the RPM band 10% TPS, which would cut off fuel as soon as all the other table requirements are met AND TPS is below 10%. Would there be any negative effect? And why are the values in standard setting are all below 1% ?

I have a 97 C5 LS1

Jochen

[Russ K]

Try logging ETC postion as TPS % SAE shows the % opening of the throttle blade to maintain idle speed. My 2001 ZO6 cam/header car idles at 1000 rpm @ 10 % TPS SAE. I left the TPS enable stock, but set the DFCO Entry RPM @ 1600, and the disable RPM to 1100. Also added 20 kpa to the enable & disable map tables. Change the spark threshold table to 15* and the Active spark A & B tables to 10* Leave the Entry Spark Blending table stock at .20 or the DFCO cuts in too quick. This is very annoying when the cruise control is on and going down a hill. The DCFO will keep cutting in and out if the Spark Blending table is higher than .20. My DFCO works great with this set up.

Russ Kemp

[Jochen]

Thanks for the detailed description.

But as long as i dont touch the "DFCO Enable vs. RPM" table, which has a maximum of 1% Throttle opening, doesnt that mean that DFCO will never get enabled, regardless all other parameters that i change?

My TPS never goes below 2-5% even when not touching the throttle and regardless which gear i have selected.

Jochen

[Russ K]

The DFCO enable tps vs rpm is not using the TPS SAE, it uses the ETC Pedal Position%. So if you log this PID, you will see that at idle the TPS is 0%. Like I said before, my idle TPS SAE is 10%, but my DFCO works fine.

Russ Kemp

[Jochen]

Upps, now i understand what you mean - Sorry.

So i can leave this table alone and concentrate on the tables you mentioned.
How about changing the speeds in the table for the different gear ratios? I realized that the "disbable below speed" thresshold seems to be very high throughout the gears. Lowering them to keep DFCO enabled should as well have a positive effect on fuel consumption, right?

Thanks for helping!

Jochen

[5_Liter_Eater]

I stumbled on this thread on accident and I'm glad I did. I tweaked my DFCO to get rid of a surging on decel and it has worked pretty well but I do get some bucking on entry and diving on exit, even while cruising. I think the main reason is I thought like Jochen that the TPS Enable being so low would prevent if from ever coming into effect so I bumped my TPS Enable to 8% and this causes DFCO to kick in while cruising.

I also bumped the enable MAP (to 29 from 19). 19 KPa is really deep decel. I also lowered my enable RPM and speed.

Can you explain the logic behind the changes to the threshold and active spark tables?

[Jochen]

Thats what this kinds of Forums are really great for! People who know things help other people to clarify issues.

Maybe Keith or Chris should add some info to the help file within HPTuners Software, as for me it was not clear what value the DFCO Table responded to (ETC Postion instead of TPS SAE).

Thanks again for explaining!

Jochen

[Russ K]

Can you explain the logic behind the changes to the threshold and active spark tables?

The Spark Threshold table is the value the spark timing is retarded to enter DFCO. The Active Spark tables are what the timing is while in DCFO. So by raising the the Spark Threshold table, less timing needs to be removed before entering DFCO. I raise the Active Spark tables so that the timing doesn't have to advance as much when exiting DFCO.

Russ Kemp

[Pro Street]

Try logging ETC postion as TPS % SAE shows the % opening of the throttle blade to maintain idle speed. My 2001 ZO6 cam/header car idles at 1000 rpm @ 10 % TPS SAE. I left the TPS enable stock, but set the DFCO Entry RPM @ 1600, and the disable RPM to 1100. Also added 20 kpa to the enable & disable map tables. Change the spark threshold table to 15* and the Active spark A & B tables to 10* Leave the Entry Spark Blending table stock at .20 or the DFCO cuts in too quick. This is very annoying when the cruise control is on and going down a hill. The DCFO will keep cutting in and out if the Spark Blending table is higher than .20. My DFCO works great with this set up.

Russ Kemp

Just found this thread and set it up in my tune!
I will give it a try this weekend.
Thanks Russ for your help

[Pro Street]

Russ I have a ? about these timing tables in DFCO.
Do I put timing in the tables below 2000 rpm or where there is 0's?
See attachment.
Thanks for your help!

[Russ K]

I change the first table to all 15* and the next 2 tables to all 10*

Russ Kemp

[Pro Street]

I change the first table to all 15* and the next 2 tables to all 10*

Russ Kemp

Thanks Russ!

[Kaploww]

Holy old thread right?

Just applied these values, and they worked fantastic. Just wanted to give some positive feedback, and thanks. I've been messing around with these settings for a week with little to no success.

I am still having a hard time understanding why it is that the values work the way they do, but right now, everything is working, so I'm happy hahaha.

For instance, why does increasing both the MAP entry, and MAP exit by 20 allow DFCO to come on more appropriately. Why can't I just adjust one (I have tried) or the other...

Also, why does decreasing the entry, and exit values only work so far? I tried setting them to 800/1000, and DFCO would not work at all.

I'm guessing these are related to other parameters, and I am still not grasping the big picture. I'm used to using the Commander 950... Set TPS value that you want the fuel to turn off, and and set the RPM that you want to turn back on... lol Too easy.

This stock ECU programming is WAY above my head so far.

[Kaploww]

Ok... settings work... how do I get them to enable faster after clutch use? Seems like there is almost a 3-4 second delay.

[racerx203]

I've tryed all the above without success. Maybe i'm not clear when i log historgram in VE ERR% it logs - decel valves that screw up my tune is there a way to filter decel out.

[Russ K]

Disable the DFCO by maxing the enable temp when WB tuning.

Russ Kemp

[Kaploww]

Well I finally did it. I managed to turn my engine into an air pump under all conditions of deceleration above idle.

And it only took me a 5 days an hour or two a day... hahaha

It's uploaded, and awaiting approval under my username.

[racerx203]

Well I finally did it. I managed to turn my engine into an air pump under all conditions of deceleration above idle.

And it only took me a 5 days an hour or two a day... hahaha

It's uploaded, and awaiting approval under my username.

Can you show Tune file or e-mail me. I do have temp max out.

[Kaploww]

Here you go.

Stock 1999 Lingenfelter TT 650 6 speed. The Enable Map vs Baro is very important apparently. Look at your map at idle while the car is warm. Set the enable 3-5 kpa lower than the lowest value you see while the car is idling, and the exit 3-5 kpa higher than the highest value you see while the car is idling.

The enable RPM entry vs Gear needs to be set at least 50rpm higher than idle. and the exit can be 1 rpm lower.

The rest of the setting should be pretty universal.

I loaded a scan of the car while I was just driving around so you could see how it works.