Is this normal?

[Silverstanger]

OK today I was going up a very high bridge. I stepped on it and it downshifted to 3rd. I only gave it about 50% throttle.. or just enough to make it downshift and hold the same speed. So it did hold the speed.

 

Well after about 10 seconds or so.. all of a sudden it just started climbing the bridge fantastically.. instead of holding 70mph it started climbing!!

 

I tried it a few more times on my trip today and it does it no matter what RPM or gear. It is not the Torque converter locking or unlocking.. I know when that happens and it doesn't make THAT much difference in power either way.

 

This is like the truck makes a major adjustment to the air/fuel or timing or something.. It goes from struggling to chuggin!!

 

Any ideas?? I would like to get it to pull like that all the time:

 

Known problems with my vehicle is.. when it is cold in the morning and periodically when it is even hot it stumbles badly or sputters through the intake if I give it too much gas.

 

 

I DID check to see if it does it WOT and it don't. It has to be a non-WOT thing that is happening. Matter of fact this TBI is so sad that if I press the gas more than half-way it really doesn't make a difference in power until like 3500rpm +.

 

It has no low end torque at all. Do I have to put 2" exhaust or what?!!

 

Any ideas..?? Thanks!!

[Silverstanger]

oh and what I meant is.. I did check to see if IT, being the 10 seconds before it takes goes way faster thing, NOT the stumbling problem.

 

The stumble does it worse when I am WOT.

 

IS there a way to adjust the fuel pressure temporarily to see if I need more fuel.

 

The fact that it does it more in the morning, when cold, tells me it's more fuel needed.

[SteveCZ]

Whens the last time you changed your fuel filter?

 

Air Cleaner?

 

Just some thoughts?

[Silverstanger]

changed fuel filter about two weeks ago, clean air filter regularly - K&N.

 

Also there is no restriction in the exhaust.. it is always loud!!

 

No CATs.

 

Its not a restriction.. its something the computer does.. but I am not sure why.

[seadoons]

Mine does the exact same thing you describe...5.3" with 43k miles on it. My fuel filter was replaced at 30k, and it gets a new air filter every 15k. I did dump a bottle of STP fuel injector cleaner in it, and it seemed to help a little, but it still does it. Don't know why...

[Yukon98]

 

How old are your O2 sensors? I had a stumbling from take off and it was the upstream O2 unit.

[Silverstanger]

I only have one O2 and it is not heated..

 

I think the O2 is fine because after it heats up it runs alot better.

 

A conversion to Heated O2 sensors would be alot better!!

[chevy38fan]

first off, if you took the cats off without getting something to bypass those O2 sensors, the computer will start to malfunction. those O2 sensors are detecting bad exhaust emissions and are going nuts. buy an O2 sensor simulator or a computer programmer that can bypass it. I've heard of MANY problems with pickup and/or fuel mileage cause they took the cats off and didn't do anything about the O2 sensors.