The 1947 - Present Chevrolet & GMC Truck Message Board Network - View Single Post - She won't fire up. Please help me! I"m at a complete loss!

Custom 68 · 08-01-2013, 11:23 AM

Yes tune it, I would not hammer on it till you do. The amount of fuel required for the 6.2 will be much different that that for the 4.8. Plus I would expect the injectors are different so that calibration will need to be accounted for. I would be very cautious until you get a better base tune.
OK, I have hp tuners so I grabbed a stock 4.8 and 6.2 from the repository. It appears they both have the same tranny I think. However there are different settings on the tranny depending on which one either the 6.2 or 4.8. Plus there are some huge differences in the injectors so yes It might run but not right with the smaller tune.
If you can get a stock 6.2 tune flashed on there it might clear up most of these problems. Be careful till you do.

08-01-2013, 11:23 AM	#72
Custom 68 Registered User Join Date: Nov 2001 Location: Springfield, MO Posts: 2,928	Re: She won't fire up. Please help me! I"m at a complete loss! Yes tune it, I would not hammer on it till you do. The amount of fuel required for the 6.2 will be much different that that for the 4.8. Plus I would expect the injectors are different so that calibration will need to be accounted for. I would be very cautious until you get a better base tune. OK, I have hp tuners so I grabbed a stock 4.8 and 6.2 from the repository. It appears they both have the same tranny I think. However there are different settings on the tranny depending on which one either the 6.2 or 4.8. Plus there are some huge differences in the injectors so yes It might run but not right with the smaller tune. If you can get a stock 6.2 tune flashed on there it might clear up most of these problems. Be careful till you do. __________________ Dave 1968 Custom Chevy with turbo charged 5.3 gen III 4l80e swap 1967-71 GMC 3/4 ton long step 4x4 (not sure what year exactly?) "A good friend will bail you out of jail...but a true friend will be sitting next to you saying "that was frekin awesome". "If it doesn't fit force it...If it breaks then it needed to be replaced anyway!"