Q on boost VE table

[ttls1]

Just a quick question, should the values in the 105kpa V Rpm cells match for both Boost VE and Main VE tables? I have just noticed they dont in my tune and thought they would have to be very close. Cheers

[darcy]

They should be set to match.

[ttls1]

Ok thanks for that, Any chance you could have a quick look at my tune and see if there is anything else obviously wrong. I had to cut and paste all the engine data into this COS as my orignal tune was COS 5 but based on a holden tune with 4l60e. As holden never used a 4l80e I couldnt compare and just copy trans segments. I had to use a 6.0L COS 5 tune. I installed the 4l80e last week and it appears to drive fine but I think the tune may be a bit messy. Made 315Kw on this tune. Vehicle is a Landcruiser with twin turbo LS1. Cam is 224,224,112.
Cheers.

I have merged the two tables in excel and graphed. Looks a bit untidy where they join at 105Kpa ??

14893

[joecar]

The idea is that the Boost VE table continues on from where the Main VE table ends (the 105 kPa column)... if the two 105 kPa columns are different then you get a step change in airmass (and consequently fuelmass) as the operating point crosses between VE tables.


For now, if you don't know which 105 kPa column is correct, you could average them and use this for both.

[Millsy]

How much boost are you running?

[darcy]

Ok thanks for that, Any chance you could have a quick look at my tune and see if there is anything else obviously wrong.


I'm by no means an expert, but a few things stand out to me;

A0008 isn't adding any fuel for cold starts.
B0101 looks low in the low-RPM/low-MAP range - possibly done to try and improve fuel consumption?
B3613 PE enable of 95MAP, together with B3616 PE enable of 95% - looks bad as this mean no enrichment until 95% throttle, but B3647 is saving you here. I would look to start richening up your B3647 from 65MAP - this will improve throttle response off-boost.
B4001 - just to check, do you have 82lb/hr@3bar injectors with a boost-referenced FPR set at 58psi base pressure?
B5914 - low octane spark table is the same as high octane. Suggest giving yourself 8deg difference generally, 4deg around idle.
B5932 - I tend to match the high octane spark table so the transition between base spark and main table is smooth - maybe not such a big deal in an auto

Is the auto a built unit:
D1108-D1111 1>2, 2>3 Shift times are all zero'd out, 3>4 @ 0.1s. 0.0s disables adaptive shifting, Try 0.2-0.3s
I think it'll be quite rough in in the very light changes areas.
You have pressures in the Standing Shift tables. This will really bash it into gear when you select drive or reverse. Definitely amend these.
For the Base shift pressures, having 10psi in the very lowest tables is also unnecessary.
For 1>2, I'd suggest 0psi upto ~30-44psi, then ramp up from there to 90psi before you reach whatever torque you see at WOT. (Not sure where this wold be in you turbo setup)
D3801 - the force motor table looks like it might be skewed to result in higher pressures than commanded.
Torque reduction is removed.

This is a good thread for understanding auto tuning http://forum.efilive.com/showthread.php?1723


Cheers
darcy

[ttls1]

Damn this is great info, thanks Darcy for taking the time to look through it. It's a little sluggish off boost and a pig to drive until warmed up so I think you nailed it there. I have limited experience in tuning but really want to understand it a lot better so the items you highlighted will be a good starting point for me. Its running 11psi and the auto is stock. Also yes it has 80lb injectors and I run 58psi

[ttls1]

Ok I have made the changes to the tune that you suggested, was a bit unsure about the PE enable and how far to richen up B3647. Could you please explain how far I should go etc? I also copied the trans pressure segments from a stock silverado tune and made the recommended changes from the tutorial link you posted. I had a bit of a guess at the VE table low map/rpm range so hopefully it will be better. I have attached the updated tune. Unfortunately I am unable to take it for a drive until next week as im stuck at work.

Thanks again

[johnv]

14908

Attached a tune file for you.
made a few changes to fueling for you. (Check the history)

I like to use the commanded fuel table to control fueling out of boost,
the PE MAP threshold has been raised to 120 kpa (2-3psi) and PE TPS threshold lowered heaps so boost boost will be the parameter that determines when it enters PE,
I find this gives a better progression of fueling when entering boost.

Once your happy with the VE table and fueling, you can work on the timing some more.
I run close to NA High oct timing table and use boost timing table to progressivly pull timing in boost.

You can build an overboost safety margin into your tune by adding fuel in the boost VE table above your max boost setting and pulling extra timing in your boost timing table above your max boost setting.

[ttls1]

Thanks a lot John, really appreciate it. I will post some feedback next week when I get back and do some testing.