Lacking Power?

[f550maranello2]

Hello Everyone,

Got a 1998 k1500 suburban with the 5.7 a year ago.
Starts and runs fine, but I notice on the highway it lacks passing power.

Since the truck is new to me Iv done the following for maintenance:
Plugs/wires (Delco)
Cap/rotor (Delco)
All new O2 sensors (AC Delco)
Fuel filter
Air filter
Checked fan clutch
Belts/hoses

What I'm running into is what seems like poor acceleration, I have old vehicles so Im familiar with 90's Gm's but I feel this suburban should move a bit better than it does.

I have a Tech2 clone, there are NO codes present, there is no hesitation or surging, I have 22 inches of vacuum at idle and 23 ish at 2krpms.

I checked the O2 sensor's today and both upstream switch fine, the down stream sensors while idling @2krpms are both around .100 volts and are pretty steady... I checked the cat converter inlet at like 380 degrees F on both cats BUT 240F on the outlets which leads me to believe the cats and doing ****.

What do you guys think?

 

[0xDEADBEEF]

Does it downshift?

 

[f550maranello2]

Does it downshift?

It downshifts but takes more effort than I would think is normal.. The trans otherwise shifts nice, its got 97k on it..

 

[Caman96]

How many miles on motor? What is fuel pressure? Clogged cats? It is a heavy truck too, maybe it’s fine.

 

[f550maranello2]

How many miles on motor? What is fuel pressure? Clogged cats? It is a heavy truck too, maybe it’s fine.

97k on the motor/trans. I have not checked the fuel pressure yet. I wanna blame the cats from my findings but I wanna confirm

 

[Nad_Yvalhosert]

I thought a sign of a working catalytic converter was it being hotter at the outlet.
Hotter at the inlet suggests a restriction in flow and being partially clogged...

A few years ago I drove my 1500 Yukon and my 2500 Suburban. There were both equipped with the L31 5.7 Vortec, same size tires, same axle gear ratio, but the Suburban was noticeably sluggish at highway speeds. Both ran well without codes and I never did figure out why.

 

[f550maranello2]

I thought a sign of a working catalytic converter was it being hotter at the outlet.
Hotter at the inlet suggests a restriction in flow and being partially clogged...

A few years ago I drove my 1500 Yukon and my 2500 Suburban. There were both equipped with the L31 5.7 Vortec, same size tires, same axle gear ratio, but the Suburban was noticeably sluggish at highway speeds. Both ran well without codes and I never did figure out why.

That makes sense to me, and both cats are hot at the intake and way cooler at the outlet. I guess since I have nothing to compare to as Iv never driven another suburban.

 

[0xDEADBEEF]

Honestly, lack of highway passing power sounds kinda normal. It's not a Ferrari, not even a Dino. (Riffing off your screen name)

~2.6 tons to 255 HP (when new) and it's a brick.