Quote Originally Posted by arveetek View Post
The ol' Tahoe is running great! No issues now after approx. 2,500 miles. Any weird sounds have either disappeared or I've gotten used to them. Seems like she idles smoother now.

I was a bit worried about the fuel mileage at first. After a 1,000 mile break-in period, I started logging the mileage. My first tank came back at 14.5 mpg! That shocked me; I had never seen that low of daily driving mileage before. I usually saw a consistent 17.5 mpg. Best tank I ever had was 18.5 mpg on a road trip one time.

But every tank since then has improved. The next tank was 15.5; then 16.1. Today I recorded 16.85 mpg.

I don't think my driving habits have changed that much; it's quite possible that early on I was really mashing the go pedal and enjoying the turbo spooling up; I may be driving more conservatively now, but it's also possible the engine is still breaking in.

Hoping that soon I'll see the 18 mpg I was getting before.

Casey
As I recall, your Tahoe has 3.42 gearing... My 3.42 geared 1982 GMC K1500, with a fresh 6.2L and Banks turbo and TH700R4, would deliver 24 mpg commuting 50miles/day. I checked dozens of tanks of fuel to get that number. It was super efficient. I suspect some of the fuel mileage we're both seeing (Sarah's Blazer is doing about the same as your Tahoe) is due to the DS4. I'd wager a few bucks that if we were to install a DB2 fuel injection pump, the mileage would be better.

I've read about the TH700 being a more efficient transmission than the 4L80-E. That may be some of it.

Sarah's Blazer engine is equipped with the small port precups, as it was from the factory. Our 6.5TD Power project truck, with 4L80-E, 4.10 gearing, and a DB2 marine pump would consistently deliver 17-18 mpg. That engine had the large port precups. It delivered 21-mpg once when driving between Lolo MT and Lewiston, ID on US-12. (slow winding road, averaging about 60-mph, slightly downhill - a river valley - most of the way).

Jim