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Speed density Tune GM gen 4

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Hi Guys

If my speed density tab in HP Tuners is the same as a stock 6.0ltr Commodore dose that mean it has never and a speed density tune its a 09 ve ssv ute with vcm otr ,3" cat back ,C.H.E. LS Trunnion Kit, vcm5sc cam and DOD Delete its 303 RWKW . It has been to 2 tuners since i have had it. who ever had it before me stuffed the car it was mafless and running like crap and a locked ecu . its has a maf sensor back on now . I have been able to stop it from stalling in carparks my self since getting it back from cam and tune . I Tryed to do a SD tune but deleted my log by accident had to add 10% fuel to get out of park is That normal for it to stall with out extra fuel. And runs in open loop maf only better than close loop .

Hello Justin,

There are a couple of options for control with GM/HPTuners. As OEM it will primarily use the MAF sensor and switch to speed density for transients, but most tend to run a software patch to use SD full time with a traditional VE table as MAF can be airflow limited and the sensor need to be spec'd correctly for the AF requirements; MAF does however take in to account air density changes due to temperature and humidity etc. so not all bad.

If the airflow had been increased in the low throttle areas then the issue with stalling off throttle or steady transients could well be down to insufficient fuel in which case calibrating SD and ICAV could improve things. In addition to this fitting a high lift/long duration/big overlap cam will reduce gas speed at low engine rpm reducing combustion efficiency and the amount of idle torque available. To improve this optimising the injection timing and increasing the idle will help but its often the case that the engine will need to be particularly rich to initiate combustion due to the low levels of swirl/tumble/squish caused by low gas speed.

There are a couple of worked examples in the Practical Re-flash Tuning course that may be helpful.

Also you may find these webinars useful

Thanks Scotty88

I am doing the Re-flash Tuning course at the moment.

I spoke to some tuners and they recommend do a SD tune to set my Ve tables to help my low rpm range .

When doing my maf I were doing my runs in second in my auto as I'm doing it on the road even no I were taking it to 6400 rpm at 120 kh I were only at 33% open throttle do I need be a bit harder on the peddle