P0172, P0175, P0420, P0700

Excellent points. So, where would I begin?

I could change the cat pretty easy.

I am unaware of how to adjust the fuel mix. I have changed the fuel filter. Could the problem be with the fuel pressure regulator?

I have no clue about the transmission code. I assume this is the most difficult issue. Yet, possibly the most urgent.

Any ideas?

Thanks,
LEB

Paul,

Where'd you find my picture? :)

I did clear the codes after changing the plug wires, distributor cap and rotor a week or so ago. These codes are the same ones I had before I cleared them. (Yes, I verified that the codes were cleared).

So, assuming they are correct, what plan of action would you recommend?

Thanks for your help.
LEB

Paul,

Thanks for the help.

I found the codes using an Autoxray. Unfortunately, there wasn't any informaiton, and I had trouble trying to figure out even what the issues were.

So, I ran down to my local oil change place and they have one of those SAM Onboard Diagnostic Report. For $15 you get a nice report of the codes, a short explanation and prossible causes. It also gives an urgency level.

For the P0700 it says: Transmission Control System (Malfunctin indicator Lamp Request) This falut code indicates when a problem in the transmission control module (TCM) malfuncation indicator lamp (MIL) illumination request circuit is present. Possible Causes: Defective powertrain control module (PCM) Defective Transmission control module (TCM)

The first three codes, as you point out, could all be fuel related, but not the P0700. The PCM monitors all of these.

Do you think it is possible that the problem is the PCM, or should I stay with the fuel system first (pump/regulator) and see if that clears anything?

Appreciate your help.
LEBoyd

Paul,

I forgot to add that it is having trouble starting - i.E, it turns over for a 3-5 seconds before hitting. Again, this could point to the fuel regulator or pump.

Thanks,
LEBoyd

The SAM system has four urgency levels, A through D where A is something like "get to the shop now, don't collect $200" and D is something like "oh, btw".

The P0172, P0175 and the P0420 are C, and I quote, "Service Soon". The P0700 is B, "Important, Service As Soon As Possible".

The exact Possible Causes are:

P0172 - "Engine Oil Contamination"
P0175 - "Engine oil contamination"
"EVAP canister purge value leak"
P0420 - "Cylinder misfiring"
"Damaged catalytic converter"
P0700 - "Defective powertrain control module (PCM)"
"Defective Transmission control module (TCM)"

Now, it doesn't specifically say "These are 'or' possibilities when two or more are listed." But I make this assumption by the way it is listed. In other words, it appears they are "or" and not "and" (e.G, the PCM and TCM are fired."

This SAM systems seems pretty good, as it is a detailed paragraph on what the code means. It specifically says "System Too Rich (Bank 1)" for P0172 and Bank 2 for P0175.

I have ruled out the oil issue for two reasons. First, the oil has been changed every 3,000 miles since it was an infant (my best friend owned it before me so I know its history). Second, the last oil change was less than 500 miles ago, and third, the oil on the dip stick is clean and feels "like good oil should" (if feeling the oil is any valid indicator).

I tried your recommended test (turn key on for 7 seconds without cranking, turn it off for 7 seconds - did this 5 times) and it was still a hard start. When I turn it over for 3 to 5 seconds (even after the test), then turn it off and try again, it seems to start very quickly (like my 97 does).

Thanks, Paul.
LEBoyd

Paul,
I did forget to add, that the hard start is not ALWAYS. If I start the truck and then turn it off, it does start as expected when I restart it even after a few minutes.

Thanks,
LEBoyd

Well, that's $200 and hours of work saved!

I could just change the regulator, although it is also some work. Based on my non-professional Chilton's and popping the air flow off, it appears the regulator is actually beneath the intake manifold. Is this right?

If I buy a gauge, from where would I measure? There are the two lines coming into the top of the manifold that have the two nuts that look like they hold them in place. Would I remove that and measure there, or?

Thank you, once again.
LEBoyd

Paul,

Thank you very much for all your help. I have tried to give you feedback, but as you probably already know, new people have no points.

Thanks, again.
LEBoyd

Paul,

As an update, I replaced the Fuel Pressure Regulator yesterday. It seems to have fixed the problem. My daughter will have to drive it for a while to see if any code comes back, but the hard start is gone.

Thank you for your help.