Accerlation problem 99

[jakeatkins]

I have a 99 Tahoe 4x4 5.7 180K

This has been a great vehicle up until the last few months, problems are starting to creep up. Expected for 180K and up until now I have been able to diagnose and fix everything that has come up.

Whe I try to accelerate from a stop or a rolling stop the truck will flat out not accelerate for about a block then it opens up. I can push it too the floor and the rpm climbs very slowly then she takes off. It usually happens when I have just started her and pull out of my drive way but also after driving for 50miles or so when I go to pass on the highway she wont accelerate.

I am thinking maybe a back pressure problem or fuel problem. Plugs, wires, cap and rotor are all new. Fresh oil. Fuel pump was replaced about 6K ago.

The only code is a downstream O2 sensor that has been on since before the problem started.

Any ideas the problem is?

 

[lesterl]

Gas mileage? How long does fuel pressure hold? check tps.

 

[Slammed]

The cat?

 

[lesterl]

Kinda sounds almost opposite of a cat issue.....

I suspect it may be flooding out on him.....

Have access to an OBD2 scantool? -watch your fuel trims when it is flaking out....

 

[samotahoe]

replace the o2! then watch fuel trim. definately could be a cat going out also

 

[lesterl]

I wouldnt replace an expensive O2 without a reason, use the scantool to diagnose the issue...

 

[samotahoe]

use a dvom to diag. thats the mistake that most techs do now days is using the scan tool as a diagnosis. you need to remember its a "tool" but in any case i said that cause if he didnt know how to test it just replace it. $50 02 is alot cheaper and easier than a $600 cat plus labor for muffler shop

 

[lesterl]

A scantool can tell you alot about the sensor, most scantools will present you with o2 voltage, so why bother with a DVOM? If you want to test for a plugged cat, pull the o2 out and check for backpressure to the engine.