Ls3 problems

[tor1965]

Hi I need some advice
I swapped an ls1 for a new gm performance parts Ls3 this summer. I use the156 os and have built up my tune when braking in the engine. First auto ve then calc ve, last dialing in the maf. After a swap to 3.42 gears, I decided to set the shift points where it should be. (4l60e). And then tuned the upper part of the ve. First it was very fast. Then I got some trouble with the shifts, and it hit the rev limiter when it shifted.
And then suddenly, I ran out of summer. It was just rain cold weather and slippy roads for weeks.
Now I feel that the engine have lost power. Its fine during normal driving but it misses something during heavy acceleration, and it feels like there are some vibrations. I have checked the spark plugs and used the scan tool to balance the cylinders.
Everything looks ok.
My lc1 shows 0.45 afr richer then it is, but this was also an issue with my old engine. The maf sensor is a corvette 85 mm Pro-M sensor. It still needs some tuning but it is close to 12000 hz, is this sane?
If I set up auto ve again, do I need to take the low iat into consideration?
I have a few logs from a trip today. Can somebody please have a look?

[joecar]

Hi Tor,

Wideband shows AFR at WOT is too rich.

Looks to me like MAF is reporting too high (compare CYLAIR_DMA with DYNCYLAIR_DMA).

You may need to do a quick 1-or-2 pass correction on VE and MAF tables...

(when doing MAF, make sure to disable VE by setting B0120 to 400 or less during the procedure).

I see you're using the LS3 injector tables

[joecar]

BTW: if you're looking at Calc.VE, then the pid CALC.VE is incorrect... the correct pid is CALC.VE_Table.

[joecar]

You're losing power because the actual AFR (as measured by wideband) is too rich.

[tor1965]

Hi Jocar

Yes the wideband are showing rich. I doubted these readings because it showed leaner earlier without any changes. (After my mind)

How much difference can be tolerated between CYLAIR_DMA and DYNCYLAIR_DMA?

When doing auto maf, is it ok to use the same settings as for auto ve except for the B0120 and the settings for failing the maf?

I always unplug the maf, but have seen the lowest value from my maf table in the log file. Is this ok?

The ls3 injector table was recommended first I modified the tables from a 2010 Camaro but something didn’t look good in my logs.

I don’t understand what you mean with the Calc.ve pid? In my log and map it says calc.ve_table ?

I have one question regards my calc_pids.txt. The displacement of the Ls3 engine is listed in the stock 2008 corvette tun as 0.775000 liter. 0.775 x 8 = 6.2 L is this the correct value to use?

I am setting up a new calc ve tun today, and take it for a drive. It is sunny but I think the outside temperature is between 5 to 10 degrees Celsius. Wouldn’t this cause the ve to be to low?

[joecar]

When doing auto maf, is it ok to use the same settings as for auto ve except for the B0120 and the settings for failing the maf?

Yes, that is correct.

[joecar]

I don’t understand what you mean with the Calc.ve pid? In my log and map it says calc.ve_table ?

I added this to my copy of your log when I viewed it... your log contains CALC.VE.

I have one question regards my calc_pids.txt. The displacement of the Ls3 engine is listed in the stock 2008 corvette tun as 0.775000 liter. 0.775 x 8 = 6.2 L is this the correct value to use?

Yes, that is correct.

I am setting up a new calc ve tun today, and take it for a drive. It is sunny but I think the outside temperature is between 5 to 10 degrees Celsius. Wouldn’t this cause the ve to be to low?

The VE table has units g*K/kPa... i.e. airmass "normalized" for temperature and pressure... you should be ok.

[joecar]

How much difference can be tolerated between CYLAIR_DMA and DYNCYLAIR_DMA?

When VE and MAF are both correct then those two will be the same...

i.e. the same cylinder airmass will be computed from either of VE or MAF.

In the pic I posted of your log, at the cursor the values are 0.94 g and 0.92 g... they're close to each other, but they're both a little too high for naturally aspirated... in other places the difference is greater.

If you also log DYNAIR you can compare this with MAF.

[tor1965]

Hi Jocar
and thanks for the answers.

CALC.VE was selected on my laptop in addition to the calc.ve_table. It is now removed to prevent mix up :-)

[joecar]

Ah, I see, I spelled "VE_Table" incorrectly as "VE_TABLE" in my calc_pids.txt file, sorry my mistake

when I corrected my spelling, I do see VE_Table in your log;

yes, delete CALC.VE, it causes confusion.

Thanks.