For all you professional mechanics?

Question

I have a 98 5.7 chevy engine in my 90 1500 4x4. the 98 engine has the original tbi system from 90 istalled. im guessing to make the computer work properly. the engine runs good but seems to not have much power. my 96 5.0 vortec seems to have much more power. is this loss of power due to the tbi unit installed on an engine that wasn't designed for it? Im just curious. any help would be great thanks.

Answer 1

I've got a 91 Chevy 2500 w/350 and it has great "pulling" power, but not much for "top end" power.

That's just the way they are.

Answer 2

sO LET ME GET THIS STRAIGHT, YOU PUT A 1998 350 ENGINE IN A 1990, BOTH HAD THE TBI UNITS, BUT YOUR 96 VORTEC SEEMS TO HAVE LOTS MORE POWER...iTS ALL IN THE PCM..iF YOU WOULD LIKE FOR THE 90 TRUCK WITH THE 98 350 TO HAVE THE POWER AS THE 96 THEN YOU WILL NEED TO CHANGE THE PCM OR AT LEAST GET A COMPUTER UPGRADE...EVERY YEAR, SOMETHING IS CHANGED IN THE ONBOARD DIAGNOSTIC TO MAKE ENGINE MORE EFFICIENT..YOUR 305 DOESN'T HAVE MORE POWER THAN YOU 98 350...IT IS JUST HOW THE POWER MANAGEMENT IS SET UP IN THE COMPUTER SYSTEM...YOU FOLLOW..TAKE BOTH ENGINES...DROP THE ELECTRONICS, AND PUT BOTH WITH CARBS, AND EFI DISTRIBUTORS... AND THEY WILL HANG SIDE BY SIDE...IT JUST DEPENDS ON HOW THEY ARE SET UP...

Answer 3

the early 5.7 are gutless ,your vortec has alot more horses from the get go ,but there is a way to circumvent the ecm a little without chipping ,basically the same thing a chip will do,play on how ignorant your ecm is ,you take your timing light and check the base timing ,now shut off and disconect battyer ,pump brake 3 times to kill the keep alive memory battery and get a full reset.reconect and start up it will take a seconed for the ecm to relearn the idle so give it a few till it stabilizes /do not shut off key or engine if pos during this or you will need to retstart.basically im going to tell you how to make your ecm think the timing chain is strechted so it will stop retarding the timing so far at idle and thus letting you have some so you can get the rear tires to put some decent smoke of them.once idling turn the avance up on your light to 12 degrees and have a buddy bring just offf idle ,dont turn dist yet just preset your light after 30 seconds of off idle operation let it go back to idle now keep your light on the mark and move dist back and forth slowly for a = and - change in timing of about 4-8 degrees varying and climbing to 12 degrees slowly once 12 degrees has been reached continue fluctuations for about 1.5-2 min then on last flux bring to 12 degrees and shut down lock down dist and restart engine see if it stays at 12 degrees with the bypass or set timing mode

Answer 4

the tbi system was not meant for a large horsepower displacement. most likely cause would be that your engine is laking power compared to your other due to the effecientcy of the tbi system versus multipoint or tunedport system....

Answer 5

What is the horsepoer per engine? This may be the reason of the difference.