torque management issues?

[dian]

i am tuning a 99 c5 with a centri blower. using os 02020003/cos3. all was going well and i had the engine up to 6400 rpm at 0.6 bar with a smaller restrictor at 10.9 afr and 13° timing. then i put in the original restrictor and leaned out the mixture a little. now the mixture is around 11.3 until 5200 rpm at 0.6 bar (pulling stronger) but then starts wildly fluctuating between 11.3 and 12.9 until 5900 rpm (0.7 bar). ibpw seems unstable too. nothing weird in ve table as far as i can tell.

could this have to do with traction controll? would i see the reduction in spark when logging sparkadv? there is no change. i dont even know if car has torque reduction by throtle. maybe thats it?

any other ideas as to what might be happening. ignition related maybe?

frames 910 and 3050:

0d18.2.efi

(AD2: 0.9= 11.3 afr, 1.2= 12.6 afr)

fuel pressure is as usual btw, falling to 50 psi from 65 psi at idle (AD1).

[5.7ute]

I calculate the pcm airflow limit (512 g/sec) as being hit at frame 908 & 3043. You could try scaling the tune and see if the problem persists.

[dian]

thanks. i forgot to mention im going sd. i read about the 512g/sec limit but i thought i got rid of that with the maf. but your saying pcm limit? what exactly is "scaling the tune"?

btw, my calculations: 512g/sec correspond to 1.48g/cyl at 5200 rpm. i have hit 575 (1.66 and 17.7 ibpw) at 5200 and 0.65 boost without the restrictor before. all the values are very volatile, though.

my endevours to understand the torque limiting/cat protection/abuse management stuff have not gotten too far, but i still have the suspicion that might be comming into play somehow.

[5.7ute]

The limit applies in SD as well iirc. Easy test is to scale your VE and IFR table by the same percentage and retest. Keep an eye on the timing as it will read from a lower cell on the airmass axis.

[dian]

im i understanding right? i reduce the values in the ve table (in both tables? probably yes.) and reduce the ifr values by the same percentage? if i do this using a factor of 1.2, the pcm will read the 0.84 row in the spark table instead of the 1.00 row, for example? so i would move all values to the left by 4 rows? (a lot of typing!)

edit: not really, ill have to redo the table entierly, right?

[5.7ute]

im i understanding right? i reduce the values in the ve table (in both tables? probably yes.) and reduce the ifr values by the same percentage? if i do this using a factor of 1.2, the pcm will read the 0.80 row in the spark table instead of the 1.00 row, for example? so i would move all values to the left by 5 rows? (a lot of typing!)

edit: not really, ill have to redo the table entierly, right?

Correct. There are a lot more tables to scale especially if an auto, but the two should do for now to make sure the issue goes away.

[dian]

thanks. can you give me a hint as to what else to scale? cranking ve? what else?

[5.7ute]

I am on my phone so I can't be of much more help at the moment. Those 3 and boost VE should get you running. With the timing you should be able to copy and paste a few columns and smooth to keep the general shape.

[dian]

i see thet b5910 and b5911 depend on cylair as well. so i guess im going to scale those too.

[5.7ute]

You can. But I would verify it fixes the problem before going to all that trouble.