Calling Allan in NE Other Chevy experts

Have a question about the early Vortec engines(96-99 5.0 5.7 etc.) and the way the fueling works on them. Lets say that you were to put a 5.0L engine in place of a 5.7. At first glance, you'd think that your fueling would be all screwed up. I.E way over fueled. But between your MAF and O2 sensors, it should correct itself, should it not? It just doesn't seem likely that it would actually be a big problem. What say the experts? Thank you for all your input.

I am betting the early 5.0 and 5.7 Vortecs used a different chip in the ecm. I believe that a lot of the vehicles of that era used the same ecm, but a different chip. Could you swap a 5.7 in place of a 5.0 of similar vintage? Probably could get by.......would it run right?....probably not really, but you are correct that sensors and ecm would compensate to some extent. Hopefully someone more knowledgeable will weigh in. I know I had a 92 with a 5.7 with a 5 speed (don't hold the buying a 5 speed against me, as that is my last), and the chip for a 5 speed, and automatic was different, and I am betting not even close to being compatible, such as swapping an auto for a 5 speed.

(quoted from post at 05:23:03 08/14/15) Have a question about the early Vortec engines(96-99 5.0 5.7 etc.) and the way the fueling works on them. Lets say that you were to put a 5.0L engine in place of a 5.7. At first glance, you'd think that your fueling would be all screwed up. I.E way over fueled. But between your MAF and O2 sensors, it should correct itself, should it not? It just doesn't seem likely that it would actually be a big problem. What say the experts? Thank you for all your input.

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They use the same mass air flow sensor and injectors and I would wager the rest of the sensors are the same...

I did not look up the VCM to see if they were different...

A 5.0 would flow less air so it may just take care of itself but I would suspect the VCM would have a different program to Taylor the MAF/TPS/MAP sensors to the lower air flow...

Folks say it takes 3 thangs for a engine to run I say it takes 4...
1) compression
2) fuel
3) spark
They say air is a given...

Air is not a given its #4 on any engine...
4) air

Modern engines measure the air in grams per second :shock: The MAF calculates the airs weight that enters the engine..

Copy and past

The stoichiometric mixture for a gasoline engine is the ideal ratio of air to fuel that burns all fuel with no excess air. For gasoline fuel, the stoichiometric air–fuel mixture is about 15:1 i.e. for every one gram of fuel, 15 grams of air are required.

The 1988-1995 trucks use the removable chip. Never actually seen one though.
The Vortec equipped GMT400 trucks have a computer that had to be flashed by the dealer, or now anyone else that had the equipment to do so. The 5.0 never came with the 4L80E, where as the 4.3 did in some vans, and the 5.7 commonly came with it. I can't get GM to flash a payload to the ECM, because you need a VIN to do that, and the 5.0 and 4L80E never came together, so that's out.
I could get a place like HPTuners, or someone with EFI Live and the correct licenses to do it, but it's still a 5.7 to 5.0 swap, and I don't want to dump a lot of money in that swap.

I recently bought the truck and dumped ALOT of money in parts into it, with the intention of knowing what I had. Turns out sh!t can still go wrong. I really don't want to put a crate 350 into it, because for about the same money, I can put a LBZ Dmax/Allison from a wrecked '06 in it.
I could buy a used 350, but you just don't know what you have with that. (I know, same problem with the Dmax)
I have a 305 that I know to be good, so I'd prefer to do that. That engine had always treated me very well. Has never caused a whisper of a problem.

It would have a different program and maybe smaller injectors, everything else could be the same.

A mechanic friend had a GMC of that era with 5.7, he put a fairly hot cam in the motor, and let the computer figure the rest out. It ran and sounded great- the displacement had not changed, but for sure the characteristics of the airflow had. What do you have to lose, drop it in there and try it!

Yeah, I just reread your post and see it was the newer ecm whereas mine was a 92 with TBI and removable chip. If it were me, I would probably toss the 5.0 into it and see what happens. Air flow is the main difference between the two engines, and a lot depends on the two engines, or differences between them such as heads, injectors, etc. Some 305 heads likely flowed better than some of the early 350 heads. You might also be able to trick the ecm by freeing up the exhaust as well. I do not recall if those had the O2 sensor after the catalytic converter yet or not, but removing the cat would free things up. I removed a cat on an older S10 pickup with a 4 cylinder in it, and it was like a completely different truck. Much more power, and better fuel mileage, and no one ever checked at inspection time for presence of the converter. And it never even threw a check engine light after removing the converter since it never had the sensor after the cat. I say drop it in and report back.

If there is enough room left in parameters of the system so it can make adjustments it may work out just fine. As others have said the TPS, MAF, O2 all have to agree on things so to speak.
Try this board out. These guys are always messing around with stuff and have allot of answers.

http://www.chevytalk.org/fusionbb/index.php?

Greg