Fuel Pressure Regulator?

This is my Bank 2 O2 Sensor with P0174 (lean Code)
DaleGrib said:
Yeah it's possible they were talking about GDI injectors I am not 100% sure on that.
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I have some good news to report....The Rich code is gone today after messing around with my O2 sensors and I'm only reading a Lean Code (P0174 Bank 2) also I have the #4 misfire back P0304 so this is actually really good news because this could actually be related if I comprehend what Joegr was saying ...the wife is sick today so decided to change my front brakes a rotors since I had the LS jacked up and on stands went to work on those O2 sensors anyway thinking and actually more like hoping the wires needed some adjusting and/or connector wasn't making a good connection but at least I'm narrowing this issue down to COP and plug potentially
 
When you replace the Fuel Pressure Regulator, is there an idle or fuel trim calibration that you have to run? A shop replaced my Fuel Pressure Regulator with a non Motorcraft one and my Idle got messed up (too high 750-800 rpm when in D and a shift to too low of an rpm when in P after idling for a minute.)
 
06LS Greek said:
When you replace the Fuel Pressure Regulator, is there an idle or fuel trim calibration that you have to run? A shop replaced my Fuel Pressure Regulator with a non Motorcraft one and my Idle got messed up (too high 750-800 rpm when in D and a shift to too low of an rpm when in P after idling for a minute.)
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That'd be a really good trick, since your LS with a returnless fuel system does not have a fuel pressure regulator!
You have a fuel pressure sensor on the fuel rail, that is read by the PCM. The PCM communicates with the REM, telling it how hard to drive the fuel pump. The REM drives the fuel pump as instructed. In this way, the fuel pressure is regulated with some variance that is accounted for by the PCM knowing what the actual pressure is at any moment. There's nothing to calibrate or relearn. Now, what part did they actually replace?
 
Yep understand now... so it was the Fuel Pressure Sensor that sits at the front of the pass side fuel rail. Apparently they broke it while doing a thermostat housing & accessory drive belt repair and they replaced the sensor with a generic aftermarket brand and only informed me about it when I went to pick up the car. Idling high now during driving needs more braking effort to stop and at idle in Park after a couple minutes has a weird stepdown to a lower (600ish) RPM that causes engine shake.
 
You have a vaccum leak.

Sounds like they damaged all or most of the plastic lines that go to the EGR valve.

They get very brittle due to age and heat.
 
And the fact that they broke the fuel pressure sensor... tells me they most likely replaced the EGR valve.

The (big) nut on the EGR valve is pretty tight... and it is common to snap the nipple off the fuel pressure sensor when the nut comes loose.

Also... there is a metal (stainless) gasket that seals the metal tube to the EGR valve.

It's a pain to replace, and if the gasket falls out without being noticed... that is definitely a spot for a major vacuum leak.
 
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06LS Greek said:
Yep understand now... so it was the Fuel Pressure Sensor that sits at the front of the pass side fuel rail. Apparently they broke it while doing a thermostat housing & accessory drive belt repair and they replaced the sensor with a generic aftermarket brand ...
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I think that there are some threads on here where they could not get any aftermarket one to work. I think they were forced to get a good working OEM from an LS in the junkyard to get things working correctly again.

They probably did the thermostat housing the hard way by removing the throttle body from the manifold which required removal of the EGR, which is a good way to break the sensor if you don't remove it first. Tell them next time to remove the whole manifold with the throttle body still on.
 
Thanks for the leads on the possible cause... EGR valve was not replaced but likely moved out of the way during the repair. I've had the EGR plastic tubes fail before but it has set a MIL when that happens (btw the plastic EGR tube assy is obsolete.) Is the ss gasket sandwiched between the two nuts connecting EGR valve to the stainless line? Will search if the washer fell onto some ledge. Thanks...
 
06LS Greek said:
Is the ss gasket sandwiched between the two nuts connecting EGR valve to the stainless line? Will search if the washer fell onto some ledge. Thanks...
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Not sure what washer you are talking about... but yes... the stainless gasket is sandwiched between the two flat surfaces of the tube and EGR valve.

The trick is to use a plunger type claw tool to hold the stainless gasket... make the bottom bolt first... then tip the gasket up in place... then make the top bolt.
 
IMG_20230425_122742066.jpg
Is the ss gasket to left of the nut?
I just sprayed that junction (and the plastic tubes on EGR) with WD-40 and did not notice a decrease in idle.
 
06LS Greek said:
View attachment 828577660Is the ss gasket to left of the nut?
I just sprayed that junction (and the plastic tubes on EGR) with WD-40 and did not notice a decrease in idle.
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See the bolt in the upper right of the picture? There is another one left of that. Those are the two bolts that hold the EGR assembly to the throttle body adapter. The only stainless steel gasket that I know of there, goes between the EGR and the adapter and is held by those two bolts. There's no "gasket" at the flare nut, the flare seals there. Any leak there would be an exhaust leak and not effect engine operation.

As already indicated, your problem is the aftermarket pressure sensor, not a leak.
 
112B637Exhaust gas recirculation (EGR) system module connector
2W701232EGR bolts (2 required)
39Y456EGR system module
49D476EGR system module gasket (the SS gasket)
59424Intake manifold assembly
1682447937983.png
 
IMG_20230426_105351107.jpg


Nope... Just as Joe said.

There are 2 bolts under the actual EGR valve... that bolt the EGR to the passenger side of the intake elbow (going down).

Proceedure is to first remove the fuel pressure sensor first... then gently unthread the tube from the EGR valve... then remove the 2 lower bolts.

If there is still a stainless gasket in there... it will want to fall out. That is why you allow the gasket to drop on one side... then grab the gasket with the plunger claw tool.
 
IMG_20230426_111628668.jpg


Connector to the fuel pressure regulator... which is held in by 2 screws. That regulator has a nipple on it that usually gets busted when trying to unthread the EGR from the pipe.
 
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