GaryDoug

Can't tell about top or bottom. The diagram shows them as left and right. The right one goes to the intake and the left one goes to the cutoff valve. The shbox diagram is clearer (not a negative image).

Wait, maybe that is top and bottom.... if so the top one goes to the cutoff valve. I wonder if it even matters.

Red97LT1

The shbox diagram looks like the intake goes to the right port? So I would assume that it would go to the bottom port? Then again it may not make a difference.

Red97LT1

The P0174 code is back. It sometimes comes on quick or later. I am going to change the O2 sensors to see if the code follows,if so I know the problem. If it is the 02 sensor,I am going to replace both since they are $75 shipped for two.

I want to verify that AC-Delco # AFS75 is the correct parts number for them?

GaryDoug

Apparently, it is the correct number. Expand the Product Fitment section near the bottom of the page.
SENSOR. Computer Control Sensors made by GM. #19178930

Red97LT1

Thanks.Just wanted to verify before I ordered if needed.

I downloaded your program and am waiting on the interface to get here. I tried it with a blue tooth interface to see what would happen and it just kept spinning. Wanted to see if I could pull any data to let me know if it was the 02 sensor.

Red97LT1

Switched out the 02 sensors today and the P0174 stayed on Bank 2. Any ideas as to what else to check?
My cable will be here Wednesday so I can use Garys software.

Could it still be a vacuum leak? If so,it must be small enough to cause a CEL,but not so big that it pops up quick.

Update: I want to make sure that I switched the right 02 sensors. It was the ones before the cat?
Also while I was checking the shbox site,the pictures showed that my Hvac and fuel pressure regulator vacuum line was switched. It couldn't be as easy as that causing my lean condition could it?

Red97LT1

Well,code came back. What's frustrating is that the code doesn't pop up and a given time.It comes up as soon as I start the car sometimes and other times not until I have driven 5 miles+

Red97LT1

I drove to the local hardware store to pick up a few things and the car did something that is wasn't before........When I started the car,it was 3-5 seconds before it fired up and as soon as it did,the revs dropped low and the car died. I tried again and I thought I was going to have to gas it to get it to start,but I didn't have to,it fired up and ran fine.

I'm not so sure now that my fuel pump or regulator isn't on it's way out?

Injuneer

You have to understand that the PCM will not run the diagnostic until all of the requirements have been met. One of these is engine coolant temp between 120*F - 239*F. So, might set at soon as you start the engine (but there are other requirements, like closed loop), might take a while to reach minimum temp. Fuel system has to be operating in closed loop. That can't happen until the coolant reaches the required temp, the O2 sensors are hot enough to start working, and the timer for closed loop (typically 206 seconds) has timed out.

Then there is the way the PCM handles the SES light. Once the code has been set, SES light will come on, until three consecutive drive trips that the diagnostic runs, but does not fail, within the same conditions that the DTC last failed.

The PCM does not turn on the SES light until the second consecutive drive trip that the diagnostic runs and fails, if at the same conditions as the previous failure.

You can't somehow correlate the time it takes to set the code to the size of a vacuum leak (if, in fact, that is the cause).

No, switching the vacuum lines for the HVAC and FPR will not cause this problem. They both connect to the same open plenum.

Yes, if you switched the pre-cat sensors side-to-side with each other, you switched the right ones.

Red97LT1

I pulled the vacuum hose off the FPR and I had a faint smell of gas?

Injuneer

Not a problem as long as it's not wet, or a strong smell.

Red97LT1

Not wet and not a strong smell. Did you see my post #38?

Injuneer

Sure I saw it. But you asked about the fuel smell in the vacuum line, and I answered that specific question. If there is not wet fuel in the line, or a strong smell of fuel, the FPR is not leaking.

Not sure I get the point of your last post.... seems like I'm annoying you.

Red97LT1

Nah,not annoying me.It may of came off wrong,but I didn't mean it that way.
Just wondered if you have any thoughts on as to why my car did what it did when it hasn't been doing it before.It's never just died during start up.