1995 Crown Victoria codes came back

I have a 1995 Crown vic that I posted about a while back. It's putting out codes again and my engine light is on. I replaced the O2 sensors since I think they're the original and it's been 120K. the codes are as follows. P0174 System Too Lean (Bank 2), P0171 System Too Lean (Bank 1) P0401 Exhaust Gas Recirculation Flow Insufficient Detected. I've been told the EGR valves on these cars never go bad so I'm stumped.

Thanking you in advance,

JLS038

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J
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On the 4.6 engine check the PCV valve line tubes and hoses where they go into the back of the intake. They get soft and mushy and will suck air and give a lean code. You will have to look real close and sometimes take them off to see the problem. I think the lines splits out on a T and goes to both sides or something like that. :lol2: Ford has a pcv line and PCV all in one to repair the problem. Check with your ford parts dealer.

On the egr code open egr vale and see if it makes the engine pull down or run different. If not remove the back part of intake and clean passages first. They are bad about stopping up back there. Good luck and let us know how it goes. MT

Reply to
MT-2500

It has been my experience that you have a couple of things to do first. The EGR code is likely the result of plugged EGR ports in the intake manifold. You must remove the throttle bod and adapter from the intake manifold to clean the slots in the gasket surface that serve as the EGR ports. You will ned a new TB gasket unless you are lucky.

While you are there, take the opportunity to remove the IAC from the TB and soak the valve end in good TB cleaner while you continue with other things to help loosen the crud in there. Do not soak the solenoid end in solvent. Finish by giving it a good spray. This may help extend it's useful life.

The lean codes are likely a vacuum leak. The PCV circuit is frequently the cause of this because the hoses deteriorate and crack. The"Y" near the throttle body is a bad one. They also plug easily causing the PCV system to become useless and oil leaks start. Replace all of the flexible tubing in the circuit and make sure the firm parts are completely open.

While you are cleaning, make sure you clean the MAF sensor in the intake tube near the air cleaner box. It tends to become fouled making it sense less air than is actually entering the engine. The ECM controls fuel based on a bad MAF reading - thus, the lean code set by the EGO sensors. There are instruction for cleanig the MAF at several places on the net. Residue-free electronics cleaner from Home Depot with a Q-tip used judiciously works well. Don't become too aggressive - use a bit more time.

Once you have completed all this, either have the ECM reset or reset it by disconnecting the negative battery cable for at least 10 minutes. Start the engine without touching a thing and left it idle to warm a few minutes. Again, without touching a thing, hold the brake and move the selector among each of the position for several seconds until it settles down bofore moving to the next. Yoy should then be ready to drive it a few miles for the ECM to start relearning it's operating parameters.

You should then be good to go.

Good Luck, may you have a happy and prosperous new year

Lugnut

Reply to
lugnut

Good detailed info there Lugnut. Right on tract.

Reply to
MT-2500

Replacing the O2 sensor did not get rid of the lean codes because the O2 sensors are telling the truth and the problem is elsewhere. Almost certainly a vaccum leak or a contaminated mass air flow sensor.

The DPFE sensor goes bad all the time. It would be good to replace the hoses at the same time. Open the EGR valve manually to check for rough idle and stall or almost stalls. If not, then look for the clogged passages as another poster mentioned.

Don

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Don

Thank you everybody. I have a couple days off so I'm going to have start cleaning.

JLS038

1)Replacing the O2 sensor did not get rid of the lean codes because the

sensor goes bad all the time. It would be good to replace

Reply to
J

Thank you everybody. I have a couple days off so I'm going to have start cleaning.

JLS038

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Reply to
J

Thank you everybody. I have a couple days off so I'm going to have start cleaning.

JLS038

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J

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