so the wife drives a 2000 tahoe z71 with a 5.7. it has k&n intake, 3" flowmaster cat back. we have owned it about 4 months now. first checked mpg, was getting 10.4 city all stock. now with mods getting 9.3 mpg. this is with my wife driving. I would think it would be better than that. we really love every thing about it but the mileage. I know its no econo box, but my 97 5.7 2wd silverado gets 16-17mpg in town and thats with me driving ;-) any ideas? it also only has about 3k on complete tune up. I also wouldn't be apposed to ditching all the 4wd parts to save gas if it would be enough of a difference. 2wd's are hard to come by around here. Thanks

 

Is this a 5.7 Swap? If not then it should be 5.3 ... other than that the only other thing I can suggest is tuning. You threw on a bunch of mods, without a tune you PCM has no idea WTF is going on. All it knows is youre getting way more air and fuel than its prgrammed for.

 

Any extra weight you can shed always helps. Tires with low rolling resistance and properly inflated help. A general tune up, timing, and compression check (since it is a 2000) would be a good start. If mechanically sound, you would also probably benefit from having a tune done on it (pcm) as there are a number of things to optimize to add both power and efficiency. There are a number of mail order or local tuner solutions (including sponsors on right) some offering lifetime updates. cheers

 

Fyi...there was an early 2000 version of the Tahoe that had a 5.7 as I recall before they went to the new engine line up choices mid year, so it could be the original engine.

 

it is original engine. its a tahoe z71 classic, old body style. so I guess pcm is off to get a tune. recommendations?

 

justin at blackbear performance


edit:

you may also want to look into the 0411 pcm swap. It is more tuneable, allows a higher rev limit, and has a few other benefits.

 

Oh that does change things a bit... I thought they quit that setup in 99. In that case you may need to find someone with the old LS1 edit. You might have a good chance at a tune then. Im not sure if HPT or EFi offer tunning for that PCM honestly.

 

Sounds like it just needs a tune up.

 

He said hes only got 3K miles on this tune up

 

Dammit. I read that paragraph 3x and still missed that part.