VE table limited to 278 ?

[Carlos]

My tune still isn't where I want to be, but I am improving...
Today I did some driving and data logging.
At WOT between 5.500 and 6.000 I have seen the AFR going very lean.
After the run, I loaded the logs into MLV and did run an analysis, ending up in the tune I attached.
In the top corner I require values around 300, proabably 350 at 6.000RPM.
However TS doesn't accept to load this tune, I get an error message stating a limit around 278 requesting me to use 255 at max.
So I guess I need to change a fundamental setting with the injectors !?

any help aprecciated

Txs
Carlos

The logs were to big to attach here is the link
www.cobra-roadster.com/public/2015-08-17_15.47.45.zip

[grom_e30]

something does not look correct can you post the log. edit saw the log your injectors appear to be to small 150% injector duty

[Carlos]

wow - if this translates into power...

I should be able to get more flow by increasing fuel pressure, shouldn't I ?
The injectors are rate 382cc @ 3bar, max pressure is 8 bar.
I would assume pressure / flow isn't a linear rate.

Anyone experienced with flow / pressure curves?
txs
Carlos

Update: just found a calculator http://www.deatschwerks.com/resources/f ... calculator
Based on my current setup, by increasing fuel pressure by 1bar, I would (should?) gain 15% flow.
At least worth a try.

[grom_e30]

http://witchhunter.com/injectorcalc1.php there is a calculator there, at 4 bar they should flow 430 ish cc. if you lower the number of squirts you will also have a longer time to inject fuel as there is 1ms dead time each time the injector opens

[Carlos]

Thanks a lot, work for the weekend is secured now

[grom_e30]

you don't really want to go above 80-85% duty cycle ideally.

[Carlos]

do you have any experience in reducing the number of squirts, i.e. the effect on AFR?

[grom_e30]

i think it will mean a bit of a re tune in your ve table, but it looks kinda weird as it is but may give you a better afr

[Carlos]

Having checked some other VE tables, I did not find another one with that large spread / range, requiring a setting of 30-40ish for cruising up to 300+ at WOT
Engine goes lean at WOT, not only AFR gauge is telling it, power significantly drops. So from this point of view the engine seems to require much more fuel, but are these values really realistic, or might the msq being corrupt?

[grom_e30]

can you check your not losing fuel pressure at high rpm? but those numbers seem way un realistic up top. plus the duty cycle 85% is a safe advised maximum.

at 6000rpm you have a maximum cycle time of 20ms to inject fuel minus your 4 x 1ms dead time leaves you with 16ms to inject the fuel you cant open an injector for 24ms if you only have 16ms time to do it in.

[Carlos]

Will add a fuel pressure sensor and check next

[grom_e30]

how much power is the engine making?

[Carlos]

With the latest mods it shall make 440hp at flywheel

[Carlos]

Did the fuel pressure test...dropping suddenly down to 0.5bar.
Filter is clean
I will replace the pump by a 5 bar Bosch which will give a bit more reserve anyway.
keep you informed

[grom_e30]

that will do it your injectors should be easily be big enough to cover the 440 crank hp you have

[Carlos]

if I change fuel press from 3 to 5 bar, my calculator states 29% flow increase.

Lets assume my VEtable was correct for 3bar, except the top load/RPM corner.
Could I, as a start with 5bar, just reduce all VE values by 29% - would this work that simple?

txs
C.

[billr]

You are better off to flow the injectors once you have your new fueling pump/regulator system in place, all else is just guessing that will cost you time and aggravation in the long-run.

[grom_e30]

if you change the size of the injectors in the engine constants and then set the correct required fuel for you effective new injector size than the ve table should be correct as it is. you may need a slight tweak to it but should be pretty close.

[billr]

I agree with that in principle, but the OP was having fuel pressure fall off dramatically, so the VE table has a very wide spread (and even that wasn't enough); so I expect the OP is going to have to pretty much start over on the VE table.

[Carlos]

quick update
today I got the precise flow rates for my Bosch injectors 0 280 155 868, it is 492 cm³/min @ 5 bar, (382 cm³/min @ 3bar)
I corrected the parameters / reqd. fuel in my TS project and did some driving and logging. I am running too rich in most of the table, so I will redo the mapping.
Keep you informed how things worked out at the end (or ask for help again if i need ;o) )
txs
Carlos