2002 Silverado 1500 5.3L Z71..today I noticed my RPM's were (to me) low...I was going about 50mph and they were below 1500...Not sure if something is wrong with my guages or what but that seems too low at that speed...

 

What gears do you have?

 

ha, your guess is as good as mine! I just bought it a few weeks ago...so i really couldn't tell you...but I never thought of that, so it could be whats going on.

 

i got a 98 silverado with the 350 sbc an 10 bolt rear and same with my dad but his is 97. 50 mph at 1500 is exactly what me an my pops get. as for gears... pffft i have not a clue tried looking it up but never figured it out. my dads has the dealer tow package with the trans cooler and nice hitch reciever and mine looks to be after-market hitch reciever no cooler and my dads is also posi mine isnt. one day i want to swap out our axles when he isnt home hehe. but yea seems normal to me. of course... 1500 rpm is overdrive for me. i mean im in overdrive. if im not im close to 2000 rpm

 

You probably have 3.73. have your vin # ran at a dealer and get a build sheet on it. At 70 mph I am reading about 2000- 2100. I have 3.73.

 

1780 rpms, read off digital scanner connected to the OBD2 port, at 70 mph.
1500 rpms for 50 mph sounds about right. your overdrive works. that's the beauty of them large 8 cyl engines - VERY low rpms at hwy speeds.

 

well somethings def wrong...tried taking it on a 3+ hour trip to houston on xmas day...made it about 50 miles before turning around to get the other car...trans fluid hot message came on...turned truck off for a while...then headed back home to get other car then the SES light came on and the whole way home the rpms went 1500 then revved the 2500 back and forth....non stop....for about 1 sec each time...1500rpms revved to 2500 then dropped back down to 1500....damn...gotta take it in monday to get it checked out...SOB!

 

sorry about trouble.
out of curiosity, i have checked rpms on mine at 50. 1380. i am almost 60 at 1500 rpms.

 

Not for nothin', this is why I got rid of my 410 gears, at highway speeds, revs were INSANE. Got 342s, now I'm Tach-ing 1800 to 2200 RPMs at normal highway speeds. A K&N CAI compensates for the few times I need power at low-end speeds.