97 Silverado 454 a dog

acceleration

#1

Has anyone found the right combination of “cheap fixes” to energize the Chevy Vortec 454 c.i. motor that I have in my pickup? Hypertech program helps, as does K&N and Granatelli airflow stuff, but acceleration is worse than a 350 c.i. motor. Is there an ECM remap available to make this truck go?


#2

You may need the correct spark plugs too.


#3

How many miles on this truck and any Check Engine Light on? Any chance you have a clogged catalytic converter? That would sure kill any performance PDQ.


#4

Well the best bet is to first determine what condition that engine is really in. If there is a problem then you need to start by correcting it. Only after that, should you start looking for mods that might help.


#5

Are you running oversize tires?

I would also check compression in every cyclinder and check for a plugged or partially plugged cat.


#6

check your spark plug wires, my brother had a green dually silverado with a 454, and i always beat him back when i had a little 327, come to find out, he was missing a spark plug wire


#7

My one suggestion is that trucks with high-displacement engines are often geared pretty steep. Keep in mind that big truck engine is designed for torque much more than HP, and so a stock 454 might not be much faster off the line than a 350, unless the two trucks are towing yachts or something.


#8

I agree with you. Also, the whole system is designed for this purpose. The cam and heads in these motors aren’t designed to be quick. It’s designed for low end torque.


#9

New poster here. Good day everyone.
I have to disagree, the 454 should have plenty of power off the line, should easily outrun a 350 truck from the start. I currently have a 97 suburban w/ the 454 vortec and it flies!!

There is a problem with the truck. You can monitor the PCM(computer) system to ‘see’ what the PCM is seeing. The PCM can only respond to what it knows/sees. If the MASS AIR FLOW sensor is not accurate, fuel injection on time will certainly be effected. Same with the Oxygen sensors. Trouble codes may or may not be present depending on whats happening with the rest of the system.

Too many sensors and possibilites to list here. SPARK/FUEL/Compression, the big 3. Something is missing, spark advance, low compression, lack of fuel, certainly a plugged catalytic converter can cause this as well.

The best thing to do if you don’t have he proper tools to diagnose is to pay a capable mechanic to figure this out. The amount of time and money you may or may not spend trying to resolve this might be worth the ‘diagnosis fee’ at a repair shop.


#10

New spark plugs in Nov06 - no change for the better. At the same time new plug wires & complete distributor - high quality: no help. Compression OK, new injectors summer of 06. I have the same performance at 111,111 miles as I did at 27,000 miles when I bought it (maybe a bit better with the Hypertech). I have not removed the cat converter, as the original is welded inline with the rest of the exhaust system, but the engine doesn’t “choke,” it just acts as if the timing advance curve is absent. When the air is cool and moist (about 45 degrees F) the acceleration increase is quite noticeable, which indicates to me that either the airflow feedback from the Granatelli unit (worse on the stock unit) or the timing advance sensor feedback loop is not working properly - but, then, the Chevy folks actually de-tuned these big block motors in some cases so that customers would not shred the poor-quality OEM tyres in the first 100 miles (according to some of the Chevy techs with whom I’ve discussed the problem). I would think that the Hypertech would fix that. This motor is, and has been maintained, in good condition, so the problem was there when it rolled off the GM line. I haven’t checked to see if it were a M/W/F truck, but that wouldn’t apply for the motor assembly itself. No codes or check engine lights, does not burn oil or lose coolant.

This thing was behaving like this while still under warranty, and no one has been able to help me unleash this beast. It is supposed to have 300 HP at least, but would probably struggle to do 150 on a dyno. Torque, however, seems to be in line with specs - it won’t stall, even when pulling over trees, etc. at near idle. The gearing is fine - 3.83 with oversize tyres (by two sizes) gets me to a reasonable road ratio, but not radical like a monster truck. I get the same road gas mileage (14 mpg) whether I’m deadheading or hauling a ton of rocks. Local mileage drops to 9 in 4wd with 2 feet of snow.

Has anyone heard of a factory glitch in incorrect 454 ignition wiring sequence? I know of one example, but have not fully checked out my motor myself (other “mechanics” say it’s fine, but do they know that the 454 firing order is different than all other GM V-8s?).

If a computer diagnosis is the answer, none of the local mecahnics have a clue. Is there a recommended computer program that I can get (to hook up to my PC) that will let me both see the ECM functions and change what I need to for performance improvement?


#11

One thing to check? Make sure the timing chain isn’t worn out.

Tester


#12

If you want to modify the spark and fuel tables yourself you will need to burn a new PROM chip using a programmer that attaches to a laptop or PC:
http://secure.transtronics.com/EPROM%20Programmer.html


#13

I have the same performance at 111,111 miles as I did at 27,000 miles when I bought it

Based on that statement, I doubt it is related to the timing chain. I know two people with similar combination of motor/truck. Neither of those would be described as anything but a work truck.


#14

454 a DOG…Something MUST be wrong if it’s NOT snapping your neck back when you floor-it. Thats a extremely powerfull engine.

Make sure you’re getting spark to ALL the plugs. Check timing.