Chevrolet/GMC, Racing, Recreational Forum Moderator
Join Date: Apr 2009
TBI VS. Vortec 454
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.
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__________________ 2003 Chevrolet Tahoe 4X4 5.3 2002 Chevrolet 2500HD 4X4 8.1 - BlackBear Tuned
Last edited by Mr_Shamrock; 08-06-2010 at 03:44 PM.
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.
1990 Chevy Suburban, 454, 2WD, with GVendor
has always been parked in garage!
"What do you mean I should give Kodachrome a shot? ...Ansel Adams (I think?)