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Power loss and sporadic stalling

noobie
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noobie Enthusiast

noobie

Posted
Posted

The truck is a 2006 GMC 1500 Denali with a 6.0.... It had codes for upstream o2 sensors, random miss fire and a few for MAF. I changed the MAF and o2 sensors and the miss fire code went away, however the truck still won't accelerate the way it should and still stalls and has no codes. I thought maybe the fuel pedal switch (And I'm not a parts thrower atter), I thought fixed it.... still has a power loss and stalls every so often... enough that I can't drive it confidently. 

 

My next option is to check fuel pressure or change the TPS....  Maybe hoping someone here may have an idea before I even go that route.

 

noobie Enthusiast

noobie

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Would you still think that if I told you while driving and I put it in neutral, shut it off and start it back up... put it in gear and get on the pedal it accelerates fine and dandy? Then let off the pedal, get back on it and then the lack of power/acceleration issue is right back? 

 

Yes... I know I left that out in my initial post... whooops! 

richard wysong Senior Enthusiast

richard wysong

Posted
Posted (edited)

By shutting it off you are releasing the back pressure from the partialy clogged cat. Try removing the upstream 02s and see if it improves. make sure the exhaust from there doesn't melt anything or start a fire. I don't know if the parts store has the gauge to measure the back pressure in their loaner program

Edited by richard wysong
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noobie Enthusiast

noobie

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Well, being I just replaced them, they shouldn't be that hard to remove.. other than the placement of them of course... I'll get back to on this.... Thanks (fist bump) 

It's Tim Senior Enthusiast

It's Tim

Posted
Posted
18 hours ago, noobie said:

code went away

Trouble code indicates an issue with a circuit, not necessarily a component. You could have replaced a good component with something that was defective right out of the box and still not have solved the issue.

noobie Enthusiast

noobie

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Posted (edited)
16 hours ago, richard wysong said:

Let us know how you make out

Removing the upstream sensors did not do the trick. Man did it sound like a demo car though.

 

 

 

Edited by noobie
richard wysong Senior Enthusiast

richard wysong

Posted
Posted (edited)

OK, Time to check the fuel pressure AND VOLUME, use a fp gauge with a dump valve on it, if the volume is good it should stay running with the dump valve wide open. Douglas is correct that the sock in the tank may be getting clogged, I don't think it has a regular fuel filter

Edited by richard wysong
noobie Enthusiast

noobie

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Posted (edited)

Checked fuel pressure. When hitting the key just to prime it, I got 40lbs. I let it set for about 20 minutes and it stayed there. While running, it was just above 50. My gauge didn't have a dump valve on it to try that exact method. And of course the thing didn't even stumble when I had the gauge on it. Before I pull the bed and tackle the pump I may try this with a different gauge. 

 

In the mean time I figured I would check plugs... two were loose. They're original to my knowledge I'm changing them regardless being there's just under 160,000 on the truck.

 

Edited by noobie
noobie Enthusiast

noobie

Posted
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Posted

New plugs took the stumble and stalling away but, there is still a lack of power.

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