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-   -   1998 vortec 5.7 bogs down on acceleration (http://67-72chevytrucks.com/vboard/showthread.php?t=753596)

george ac 12-28-2017 10:16 PM

1998 vortec 5.7 bogs down on acceleration
 
Hello happy hollidays,
I have a 1998 Chevy Cheyenne 5.7 it was running well and idle but on acceleration would bog down, miss fire excetera and made a hole in the muffler. Then the fuel pump went replaced it eliminated the catalytic converters and put a new muffler in, nothing really changed it was a minor improvement today replaced plugs, distributor cap, rotor and fuel filter. I started up I would have bet money that the problem was solved since now I could accelerate without a problem when I took it around the block it started bogging down again same thing . Some of the fuel coming out of the fuel filter that I removed was dark. I was wondering if maybe the new filter was able to get clogged up that quickly? Thanks in advance if anybody has had a similar problem please give me a heads up thanks a lot!

diveplane 01-15-2018 12:15 AM

Re: 1998 vortec 5.7 bogs down on acceleration
 
its a bad idea really to remove cats as the computer reads on the o2 sensors

fuel air ratio mix to ecu computer. bypassing them is a crack of sh... and it will bring problems imo, and cats today hardly rob u of much power thats another myth.

when i did my truck i just renewed the cat y pipe system new 02 sensor.


your 5.7 will have multiple o2 sensors approx 3 i think or 4, and duel cats and pipe.
can be quite costly to replace, these o2 sensors are around $65 a pop.

diveplane 01-15-2018 12:27 AM

Re: 1998 vortec 5.7 bogs down on acceleration
 
The O2 sensor is mounted in the exhaust manifold to monitor how much unburned oxygen is in the exhaust as the exhaust exits the engine. Monitoring oxygen levels in the exhaust is a way of gauging the fuel mixture. It tells the computer if the fuel mixture is burning rich (less oxygen) or lean (more oxygen).

Bigdav160 01-15-2018 09:49 AM

Re: 1998 vortec 5.7 bogs down on acceleration
 
I would suggest that it's time for a injector/spider replacement. I've seen the pressure regulators leak fuel badly.

BTW, the front O2's do not know if the converters are there or not. And the rear ones are just to monitor if the converters are effective. They will turn on the MIL but shouldn't cause drivabilty problems.

diveplane 01-15-2018 04:53 PM

Re: 1998 vortec 5.7 bogs down on acceleration
 
Sure the 98 trucks it's same system

6 Here’s a specific example of how one portion of this system operates: An oxygen sensor, located in the exhaust manifold, constantly monitors the oxygen content of the exhaust gas. If the percentage of oxygen in the exhaust gas is incorrect, indicating a too rich or too lean condition, an electrical signal is sent to the ECM. The ECM takes this information, processes it and then sends a command to the fuel injection system, telling it to change the air/fuel mixture. This happens in a fraction of a second and it goes on continuously when the engine is running. The end result is an air/fuel mixture ratio which is constantly maintained at a predetermined ratio, regardless of driving conditions


Now that you've tore all your vital o2 sensors out.
System has no way to adjust air fuel mix.

Tom 01-15-2018 05:12 PM

Re: 1998 vortec 5.7 bogs down on acceleration
 
Quote:

Originally Posted by diveplane (Post 8161568)
Now that you've tore all your vital o2 sensors out.
System has no way to adjust air fuel mix.

Go ahead and quote where he said he eliminated the O2 sensors, we'll wait.
On top of that the front O2's are not mounted in the manifolds, they are in the down/crossover pipes that lead to the cats after the manifolds.

OP- have you actually tested fuel pressure or are we just making guesses about stuff right now?

diveplane 01-15-2018 06:27 PM

Re: 1998 vortec 5.7 bogs down on acceleration
 
[QUOTE=Tom;8161587]Go ahead and quote where he said he eliminated the O2 sensors, we'll wait.
On top of that the front O2's are not mounted in the manifolds, they are in the down/crossover pipes that lead to the cats after the manifolds.

OP- have you actually tested fuel pressure or are we just making guesses about stuff right now?[/QUOTE

no not tested fuel pressure myself nope, my unit runs fine.

normally u can hear the fuel pump engage for around 2 secs when ignition turns on.


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