2000 GMC Sonoma automatic transmission question???

[zieg85]

I borrowed my Dad's truck to go to Menard's.  It has the 4.3L automatic.  This is the first time I had really driven it and noticed it really wanted to coast as in no engine braking, very similar to just putting it in neutral with no slowing down and actually picking up speed going down hill.  Is this common thing to happen on these trucks?  The throttle was not sticking or anything like that as I put it in neutral and the rpms dropped all the way to 700 on the tach.  The transmission shifts perfectly and even though it has 151K on it the truck runs and drives like it is new.  The only complaint is that it seems that more brake is needed to stop than it should be.  Dropping it to 3rd has all the engine brake as you would expect.  Could the lockup converter just be in free-wheel mode in OD?  Just curious if some one knows?

[Tx_Phil]

I'm no expert on transmissions but I think what you are experiencing is by design. I have a 99 silverado 1500 regular cab 2wd with the 4.3 v6 and 4 speed automatic. It will coast like you are describing, maybe more so. I've let it coast in OD at 60mph and it drops pretty quick until about 45mph. At 45 I've been able to coast over a mile and only lose about 5mph.

Using that coasting and driving smart I can get over 22mpg from that truck. It's kind of crazy to get that mileage but it works. So what if the Houston maniacs don't like it !!

[Irish_Alley]

my 04 impala will do the same thing. i think it was designed like that for better millage but thats just me thinking also kind of like phil was talking about

[zieg85]

Thanks, I was hoping it was supposed to be like that.  At least I told dad that nothing was wrong and that it was a gas mileage thing

[blazing816]

I had a 98 Chevy S10 Blazer an it did the same thing when I was in OD. It is by design for the MPG, I did mostly backroads driving at 50mph and I use to get like 25-26mpg out of that thing and it was not rated that high as it was 4x4 also. I thought it was great, but it was a little different at first and threw me off a little too.