LM7 vs L59?

[sixt5]

i was under the assumption that all 5.3's were e85 ready. is this not true? i've been running it in MY 04 5.3 and its been doing fine. little less mpg and rough starts in very cold weather but i thought that was normal.

whats the deal?

[Frenchy]

Different fuel rails, bigger injectors on the e85 motor.

[sixt5]

im going to have to look at my vin, but if my engine was NOT e85, then would it still run the way it does?

[sixt5]

i checked my build sheet and vin, i have the lm7 with a T in the 8th digit.

[Frenchy]

If your truck isn't meant/tuned for e85, running it isn't the greatest idea. At all. The stoich point for e85 is 9.7:1 whereas gasoline it is 14.7:1. This means your PCM is trying to command a 14.7 air/fuel mix. If it's commanding that on e85 it will be running dangerously lean.

[sixt5]

needless to say, im not gonna run it anymore. Since this has happened, i think i may need to check my plugs then. could have damaged them with the lean conditions. currently at 51k on stock plugs. i really need a tune since i have no o2 sensors

lean is mean though, right? lol

[yellowdemon327]

way higher alcohol content in e85 than reg gas. 85% alcohol is def not healthy for a motor that was not meant to run it. these 5.3's are pretty darn tough tho, so hopefully everything is ok.