Issues with LS7 programming

[Jason S.]

Hi guys, I am hoping someone might be able to shed some light on an LS7 I am working on. It is a stock Z06 with a cam and exhaust (customer isn't sure what cam is in the car). At light load around 1500 to 2000 rpm, the timing is jumping around like crazy....about 8 degrees up and down rapidly. I tried zeroing out the torque reduction stuff, but it appears that it is still somehow active. Has anyone else experienced this? I have attached the log.

Thanks

[Jason S.]

I couldn't attach the cal, it's over 1 meg.

[grfperformance]

Turn off DFCO and CFCO. Also monitor idle adaptive spark. You also need to add more idle airflow. A big cam needs about 15% more air in the lower rpm ranges.

[redhardsupra]

Turn off DFCO and CFCO. Also monitor idle adaptive spark. You also need to add more idle airflow. A big cam needs about 15% more air in the lower rpm ranges.
you mean less air in low rpm?

[Jason S.]

Turn off DFCO and CFCO. Also monitor idle adaptive spark. You also need to add more idle airflow. A big cam needs about 15% more air in the lower rpm ranges.

This isn't happening in the idle range it's happening at light load driving.

[joecar]

Jason,

Posting tune file (.tun): Maximum allowed size 3.9MB
Posting log file (.efi): maximum allowed size 1MB
Posting zip file (.zip): maximum allowed size 2MB (compressed)

You should be able to post the tune file;

To post the log file, if it's too big compress it to a zip file and post the zip file.

If you're strill having trouble posting the files, send me a pm.

Cheers
Joe
:beer:

[Jason S.]

Still no luck attaching the .tun file.

[joecar]

Try to zip the tune file and see if that works.

How big is the tune file...?

[Jason S.]

Nope...won't take that either.

[joecar]

Can you email it to me, include a link to this thread in the email...

My email address is in my profile (click on my username to the left of this post, select Send email to joecar).

[The Alchemist]

http://forum.efilive.com/showthread.php?t=7401
see this post, you may be having the same problem I'm having, constant speed, low rpm lots of spark retard happening. turned out to be an over active Traction control system. Turning it off completely was the only way to stop it. Surely there must be a table that allow you to increase the torque limits to stop this happening.....
I maxed out all the torq settings under TCS by gear, input gear etc, turned off all the TCS options to "no", finally put zero's in B2522 and that put a stop to it!
Try that.

Mike

[grfperformance]

you mean less air in low rpm?

No, bigger cams need to flow more air at idle and in the lower RPM ranges due to the increase in overlap and duration. The cam is keeping the valves open longer which means the engine is trying to draw in more air for a given rpm than the stock cam.

I've also recently discovered that E85 also requires even more air in the idle airflow table than the same setup with gas.

I don't have an E38 so I'm not sure what settings you have for TCS but on the E40 we can totally disable it just by turning it off.

Be sure to monitor your idle adaptive spark and other spark tables to see if they are active.

[redhardsupra]

if you need more airflow, why do VE numbers are way lower than stock in the idle areas?

[jfpilla]

if you need more airflow, why do VE numbers are way lower than stock in the idle areas?

Because you're pulling fuel, same as adding air.

[redhardsupra]

no, adding air==adding fuel, that's why AFR=airmass/fuelmass and it's a constant dictated by the computer

[jfpilla]

no, adding air==adding fuel, that's why AFR=airmass/fuelmass and it's a constant dictated by the computer

Try lowering the VE's and tell me what happens to your AFR.

[grfperformance]

Lower VE numbers reduce fuel, higher numbers increase fuel. I'm running e85 and my VE table doesn't look anything like a gas version.

Another factor here is that large overlap cams are not very efficient at low rpms. My VE table looks like a hockey stick above 2000 rpm.

[grfperformance]

The idle airflow table sets the minimum airflow at an idle, similar to opening the butterfly on a carburetor. The engine won't allow the airflow to go below the minimum set in the table. If you set the minimum too low, the engine starts hunting because it's also trying to hold the desired idle rpm and the engine starts to die, then the computer opens the throttle, it overshoots, then tries to go back to the idle rpms, starts to die, then it does it again.

Once you have the idle airflow set properly, go to the VE table and dial in your A/F. If everything is set correctly you should only hit two cells.