gamble686

iTrader: (3)

Nothing wrong with running idc of 90% if your afr is good at wot. They may warm up if ran at wot for a long time, but unless you are running them hard frequently you are fine. I would suggest focusing on your fuel pump as it sounds like it isn't giving you a good steady supply. That said bigger injectors would be a good upgrade for down the road. 80+ will give you room to jump to 10, 12, or even 15lbs. 10.7 is really rich even for FI. Your losing power and efficiency running that rich. 12.5 is safe and spot on. 11.5 or 12 might be considered safer, but defiantly not as powerful. At idle/cruise 14.7 should be commanded. I also thought the stock injectors were 30 or 42lbs depending on the year/model, but I can't be sure. A PN# check would be a good idea to make sure.

JCunningham

iTrader: (4)

cant find anything on the part # check. at idle and cruise its 14.5-15.2 more around 15. Im going to stay at 8psi. this is only a daily driver and i plan on keeping it for a long time. I told Justin I wanted a nice safe daily driver tune and Im sure thats what he gave me. What could be done with the Fuel pump. It is a Flex fuel pump.

Boober

From my limited experience, anything over 80% and the computers control over the injectors is greatly reduced; they are essentially static with maximum desired pulse width. Is 90% generally safe? Sure, but you're leaving yourself exposed to variables that you can't normally predict (bad gas etc.). ALL of the reputable tuners that I have ever spoken with say the same thing: 80% or below IDC is ideal, 11.4-11.8 AFR@ WOT for boosted engines. I would NOT recommend anything above 12 AFR at WOT, especially with the cooler months ahead. Some much cooler/denser air and that 12.5 AFR quickly becomes 13.5 AFR and detonation is right around the corner.

It's not such an easy route to fix the fuel supply as the problem is with the entire system design. Boost-A-pumps DON'T work and the stock flex fuel pumps actually outflow units like Walbro 255's. Most serious applications are converting to a duel fuel pump setup with a return line, a boost referenced fuel pressure regulator and eliminating the fuel pump control module. All solutions approach $1,000.00 and are quite a challenge for the shade tree type. I decided to kill 2 birds with one stone. I'm installing a Alky Control meth kit with MAF referenced activation. The meth with spray once I'm above a desired frequency and not only will I get the extra fuel, but I'll get some nice IAT's as well. All for a bundle less than a return style system.

Boober

A quick search in GMT 900 subforum for "flex fuel injectors" brought a a thread where a kind person posted the HPtuners tables for: 5.3L flex fuel, 6.2L non-flex fuel and 6.2L flex fuel. I grab the image of the 6.2L flex fuel table to show you guys that I'm not blowing smoke up your butts.



You can find the other tables if you want but they show that the 5.3 flex fuel flows about 37Lb/Hr and the 6.2 no-flex fuel flows about 30Lb/Hr at 58psi.

My recommendation is still for you to go with big injectors (since you need to do it anyway). Trying to figure out a simple solution for your fuel pump issues will be met with dead end after dead end. But don't take my word for it.

JCunningham

iTrader: (4)

well the 80lbs should flow plenty at 50psi so Id be good. with the 80lb injectors will i have any drivabiliy issues
thanks
so acording to that chart at 58psi they flow 54lbs and 51psi 50.4lbs Justin told me the stock tune showed 55lbs so that is right and my truck is tuned for these injectors so im safe for now as long as i dont do alot of wot driving.
Are the FAST injectors good. I can get them for $365 or Siemens for $400

Boober

I would consult Justin as he will be the one who will be making the changes in your tune. He will likely have a database of injector data and can recommend the right ones to get.

JCunningham

iTrader: (4)

ya i sent him a email. Thanks for all the info.

JCunningham

iTrader: (4)

Pink injectors at 408kPa (4.08bar ~ 59psi): 5.599121 g/sec ~ 44.438213 lb/hr
Stock injectors at 408kPa (4.08bar ~ 59psi): 6.355956 g/sec ~ 50.444941 lb/hr

Boober

That's what my stock 6.2L injector table says. The table I posted is a little different than mine.

Area47

12.5 under boost isn't a bright idea.