I think I may have an issue with my 1995 TBI 454 2500 truck. I thought I had it figured out with a new fan clutch but it still just does not even come close to the Vortec 454 Suburban that I have. I know there is a 40 HP or so difference, but this truck just doesn't seem to pull like a big block. I did get a oxygen sensor code the other day that came on for like 15 seconds and then went out and hasn't come back on since. It almost feels like there is a restriction in the exhaust that is holding the truck back. I have only had one other TBI 454 in the past and it was a near new SS truck. I remember thinking that main difference I noticed from my 350 TBI 1/2 ton I had back then and the SS truck was the SS felt like it would just keep pulling even at highway speed when I would go to pass someone (besides that the SS trucks really weren't that impressive) IMO. This 2500 truck doesn't pull near as hard and at highway speeds with a small empty yard trailer behind it it won't pass a bicycle. Any ideas? There aren't any current trouble codes.

 

Also FYI - I just completely tuned it up (plugs, wires, cap, & rotor) and it was running the same before the tune-up.

 

Ended up being a clogged catalytic converter. She pulls like a big block now.

 

good to know. some knowledge for the file lol

 

I've got a big block 454 Suburban, and a few years ago it began to lug-down and overheat. I was really battling everything about the overheating. changed the fan clutch several times, water pump, thermostat,...etc. Was about to junk the vehicle until I took it to a good private mechanic. Turned out that the bearings on the distributor shaft were worn-out. He put the car on some sort of scope and determined that some of the spark plugs were firing as much as 10° off!!! When I picked up the Suburban, he even told me to be careful driving home 'cause it has way more power than before. He was right, the vehicle was driving like a sports car with all the power.

Anyway, be aware of the distributor shaft bearings. They are only little bronze bushings.