Well, the P0172 is telling you that the engine is running rich - adding extra gasoline to the fuel mixture for some reason.

Here is a link to fairly good step by step diagnostic process to determine what is wrong:

Chevy Trailblazer P0172: Fuel System Rich – Bank 1 | Drivetrain Resource

A common trouble code with the Chevy Trailblazer is P0172. This code number references a number given to you when you plug your vehicle into an OBDII scanner. It's not the most complicated OBDII trouble code to diagnose. It is also one of the most common. It means the motor is running rich...

www.700r4transmissionhq.com

I'm also including a pdf of how to attach a fuel injection system pressure gauge in order to test the fuel pressure. As and FYI, AutoZone, Advance and O'Reilly part stores all have specialty tool loaner programs that include fuel injection system pressure gauges. You leave a "deposit" take the loaner tool, go to your vehicle perform the test, and then when you return the loaner tool, you get your deposit back.

Good Luck!

 

Well, the P0172 is telling you that the engine is running rich - adding extra gasoline to the fuel mixture for some reason.

Here is a link to fairly good step by step diagnostic process to determine what is wrong:

Chevy Trailblazer P0172: Fuel System Rich – Bank 1 | Drivetrain Resource

A common trouble code with the Chevy Trailblazer is P0172. This code number references a number given to you when you plug your vehicle into an OBDII scanner. It's not the most complicated OBDII trouble code to diagnose. It is also one of the most common. It means the motor is running rich...

www.700r4transmissionhq.com

I'm also including a pdf of how to attach a fuel injection system pressure gauge in order to test the fuel pressure. As and FYI, AutoZone, Advance and O'Reilly part stores all have specialty tool loaner programs that include fuel injection system pressure gauges. You leave a "deposit" take the loaner tool, go to your vehicle perform the test, and then when you return the loaner tool, you get your deposit back.

Good Luck!

I apologize for the delay in responding. I've checked everything on that list and still have the code. The pressure test is the last thing. However, i dont see the PDF. Thanks for the help.

Edit: I did get it figured out. Seems my pressure is running high. I'm at 60 psi. IIRC range should be 53 to 57.

 

OK --- there are several things that can do what you state ...

1. A plugged-up/melted cat​

2. Low fuel pressure --- but you said it's higher than the norm.​

3. Plugged fuel filter --- but the '05s started to only use the filter inside the pump assy - so you can't test it by itself.​

4. Seriously bad cam timing --- but you don't have the codes to support that problem​

5. Faulty - inoperative throttle plate assembly --- I'm not 100% sure, but you may have messed it up by taking it out and attempting to "clean" it.​

6. I doubt it's transmission failure just the same as I doubt your brakes are somehow locking up. Don't go there.​

 

OK --- there are several things that can do what you state ...

1. A plugged-up/melted cat​

2. Low fuel pressure --- but you said it's higher than the norm.​

3. Plugged fuel filter --- but the '05s started to only use the filter inside the pump assy - so you can't test it by itself.​

4. Seriously bad cam timing --- but you don't have the codes to support that problem​

5. Faulty - inoperative throttle plate assembly --- I'm not 100% sure, but you may have messed it up by taking it out and attempting to "clean" it.​

6. I doubt it's transmission failure just the same as I doubt your brakes are somehow locking up. Don't go there.​

Thanks for the list. I'm not sure about a plugged fuel filter since it runs at idle fine, and revs at idle pretty good too. I would think a plugged filter would prevent that. I'm leaning towards a plugged cat. Unfortunately I don't have the $550+ to get a new one around here. This leaves me in a bad spot since I need the truck to go to work. Any suggestions on a quick fix or workaround for the short term? Thanks in advance.

EDIT: Another new development. I now have a massive squeal going on. I just moved my truck from my drive to out front and it has a mass8ve squeal. It does not change with the turning of the wheel so I know the power steering pump is ok, but it seems to be coming from that area. Any ideas? TIA

 

OK, now I've attached the pdf I mentioned earlier. Sorry to hear about the current situation. Let us know how things transpire.

My apologies for not adding the pdf earlier.

 

New things on top of unresolved old things makes life oomplicated for internet diagnosis.

The squeal could be an exhaust gasket vibrating like a reed because that's as good a spot as any for dead-ended exhaust gasses to escape. Maybe.

A very restricted fuel filter might not affect idling and could have enough fuel getting by to let you snap the throttle open, but won't let you drive when it drops the pressure because there's insufficient fuel volumn for making actual horsepower.

You need to test the pressure AND the fuel flow when you had that gauge.

The push button on the side of the gauge manifold had a piece of clear fuel line on it to watch for air bubbles and test how long it takes to pump out 16 ounces of fuel while the engine is running.​

​

NOBODY BOTHERS WITH THAT PART OF THE TEST .... did you?​

​

1. Read the running PRESSURE​

2. Push the button with the open end of the clear hose in a 16oz container​

3. Time how long it takes to pump the 16oz container full ... watching for bubbles in the line at tge same time.​

4. Report you findings then we'll test your cat and seek your new funny noise.​