Engine "lugging" at 11- 1400 rpm in overdrive at 50 mph. never used to.

[TBI355]

Hey all! New here, but love the site so far. Got a problem with my 4L60E 95 Silverado. 50 mph in OD, seems like its in way too low of gear. Engine lugs bad, like doing 25 in fifth gear with a manual tranny. Seems as tho its in fourth gear with TC locked up. things got 185k on it, might be original, shifts great, just when cruising @ 45-55 mph. Expressway driving is fine, 2000 rpm @ 70mph. I don't remember it always being like this. I thought it was because my old motor was tired, but I just put a brand new 355 with flat tops and headers in it last weekend, more than enough power, still lugs around @ 45-50 mph. It's really annoying, I have been pulling it down into 3 to cruise, but im sure that is killing my MPG's. Any help would be appreciated!

P.S. If I need to replace that trans, only a '95 will work correct?

 

[DRAGGIN95]

I do the same thing to my truck's while cruising under 55 mph I pull it down in to drive, because I don't like how lugged down they are, all of the 1/2 ton 2wd's I have owned are like that, and for me pulling the trans down in to drive doesn't hurt my mileage.

 

[darren250r]

You mileage shouldn't suffer in drive at those speeds. The increased RPM will require less throttle. That sounds like everything is working fine to me. The torque converter locks up at 45, so it makes sense that if you're staying right on the bottom limit as far as speed, OD and lockup go that you'd be lugging it. You're fine. I would put it in drive under 50 especially if there are any hills just because you don't want your converter constantly locking and unlocking or shifting between drive and overdrive all the time. That is hard on a tranny.

 

[DRAGGIN95]

You mileage shouldn't suffer in drive at those speeds. The increased RPM will require less throttle. That sounds like everything is working fine to me. The torque converter locks up at 45, so it makes sense that if you're staying right on the bottom limit as far as speed, OD and lockup go that you'd be lugging it. You're fine. I would put it in drive under 50 especially if there are any hills just because you don't want your converter constantly locking and unlocking or shifting between drive and overdrive all the time. That is hard on a tranny.

Word!

 

[TBI355]

Okay, sounds good. Thanks much for the input!