7427 PCM with

[sfara002]

I just installed Vortec heads on my 350 GMC Jimmy. I have the 7427 PCM and started working with the BJYL mask. When tuning my VE tables, how do I tune for greater than 100% VE?

[sturgillbd]

You don't. Have you viewed your datalogs and looked at your injector duty cycle? You will need approximately ~75lbs/hr +/- of injector to feed the engine with a decent max duty cycle. You can increase your fuel pressure and set the new flow rate in the bin. You will have to then retune your VE .

[sfara002]

Ok Great! I was hesitant to change the fuel rate after I upped the fuel pressure because I thought it wouldn't change the VE tables.

What i did was put the heavier spring in to up the fuel pressure, then retuned the VE tables without changing the lbs/hr in the bin file. Is there any consequences to doing it this way?

Thanks!

[sturgillbd]

The pcm relies on fuel rate to calculate pulse width for fueling. There are calculators out there but the formula is sqrt (new pressure / old pressure) X old flow rate = new flow rate . You will have better results after changing your fuel rate in the bin.

HTH
Brian