So as with everything else I finally seem to get rid of things, yet when I dont. I've got all 4 02 sensors replaced and those codes taken care of. Now I have p0172 and p0175 codes. The truck is also very hard to start and has a very long cranking cycle. I have noticed the idle while not bad seems to feel like something is missing, yet goes away doesnt feel like it's there at around 2500/3k rpm. Gas milage is also abysmal. 01 qc with the 4.7l still. Has a new fuel pump with good pressure even under load.

 

Does the system hold pressure after the pump stops?

 

I will put the gauge back on it. I removed it after I had confirmed the pump was putting out good pressure. Im starting to think I want to install a remote pressure guage so I can permanently watch the pressure.

 

They are out there. I like the electronic versions, as it is not legal in most areas to have gasoline plumbed into the passenger compartment. There are also 'isolators' available for mechanical gauges.... might be more accurate, but, also more expensive.

 

I just need one I can either insert between the rail and the feed or onto the schrader port.

 

being able to read it from the seat is sometime desirable as well.

 

Oh I want an in-cab one. Incidentally I spun on the gauge to the test port, no residual pressure at all, since the last time I drove the truck was on wedsnesday. Beginning to suspect either the FPR isn't doing its job (even though its brand new) or my injectors are leaking like a mother.

 

Does that one have an external regulator??

There is a check valve in the system somewhere as well, that failing would also have it bleed off pressure right quick.

I would expect it to bleed down to nothing over a couple days in any event.....

 

So Im finally coming back to this. Regretably I have not had a chance to install the electronic pressure gauage, but Im hoping to get a chance over the holidays. What Im noticing right now is that bank 2 both 02 sensors are locked at .93v more or less, while bank 1 sensors before and Aft seem to be fluctuating fine. And oddly while Short term on bank 1 seems normal, both long terms on bank 1 and 2 are a -33% and there seems to be a dark ring around the exhaust tip. Are the 02 sensors faulty or has my computer decided it doesnt care what the values are anymore? Also I have replaced the fuel injectors all together, but the engine feels like it no longer has any get up and go particularly after coming to a stop. I had replaced all 4 sensors with brand new denso sensors and do not have any 02 codes other than the 172/175.

 

So when you say "locked" do you mean it does not move at all or are you saying it only moves a few millivolts either way? Usually if an O2 sensor is stuck on a certain voltage its just a bad O2 sensor. Usually running rich is caused by stuck open/leaky fuel injectors or faulty O2's which you already replaced. Do you have the old O2 sensors still? Maybe try putting the old one back in to see if the behavior changes. You could also try unplugging the front O2's and seeing if the performance improves. If so then its likely the sensors. Sadly new does not mean good. Even with the good brands.