95 Crown Vic intermittent coding P0171 and P0174 (Lean Banks 1 and 2)
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95 Crown Vic intermittent coding P0171 and P0174 (Lean ... - 12/9/2006 1:28:01 PM
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Bob Wells
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Joined: 12/9/2006
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Hello Ladies and Gentlemen,
This is my first post in this forum so hello to all of you. I have a 1995 Crown Vic LX with 175k miles on it.
I first noticed the intermittent problem as a single or double clunk when it shifts from 2nd to 3rd and from 3rd to overdrive. I read the engine codes and they were P0171 and P0174 which are the lean condition for banks 1 and 2. Also spit out a P0307 (Cylinder 7 misfire) a few times.
I replaced the fuel filter as it had been in there quite a while. No change. Also had the tranny pan and torque converter dumped and new filter as fluid looked to be a pale pink with slight yellow cast. Bottom of tranny pan was very clean. Also added Lubegard Red. Not much improvement but thats ok cause I wanted to have it changed regardless.
Found nasty looking thick coolant in plug holes 1 and 3 from previously leaking thermostat housing. Cleaned out all plug holes (fair amount of dirt in all) and cleaned boots thoroughly. Stopped throwing the cylinder 7 misfire. Gently cleaned MAF sensor with Windex spray and blew dry. Now the engine runs as smooth as silk most of the time and the tranny shifts so smoothly you can't tell except from egine rpm. However a couple of times a day it starts running rough again for a few minutes, looses about 1/3 power and throws both lean codes... and clunks between gears(although not as bad).
Got a Actron fuel pressure gauge and it was 31 psi engine running and the same with engine off and key on. Read it two days later and it was 40 psi key on and 31 engine running. Possible bad fuel pump? I have been trying to catch it in the rough idle mode and check pressure but have been unable to so far. Replaced the fuel pump relay, no difference.
Checked for leaks in intake manifold but the carb spray disappears so quick that I can't tell if it is being sucked in or just evaporates. Is it ok to use water in a spray bottle? Also checked clamps to air intake valve. One has hold clamp so I tightened it , no diff. The other clamp cannot be tightened as it has no screw. Could this be a leak source? Also there is a black tube about 3/4 inch diameter that comes in at 90 degrees into a bubber boot that just seems to be a press fit. Does it need a clamp?
My other questions would be how long do fuel pumps normally last and is 31 psi marginal for running pressure? Since the car is so old and has so many miles on it what sensors if any might i look at replacing? Four months ago it threw some egr codes for a few weeks but none since. Any other ideas?
Thank You,
Bob
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Bob Wells
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RE: 95 Crown Vic intermittent coding P0171 and P0174 (L... - 12/17/2006 12:03:40 AM
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Malibu Barbie
Posts: 109
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Joined: 12/7/2006
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Welcome, Bob! There's several different things than can cause your lean air/fuel mixture problem. Here's the areas I'd like to address to try to help you:
- Air Filter - When was the last time it was replaced?
- Bad fuel pump? Yes, that's possible, as well as a leaking FPR. When the fuel pump starts to go bad, it'll usually make a constant buzzing noise - have you heard anything unusual? Also, did you use a fuel pressure gauge to check the pressure at idle while the engine is warm?
- Fuel Injectors - How old are they? Are they leaking? Have you tried using a fuel additive to clean the injectors? Remember that you usually have to run a full tank of gas with the additive before you get the best results.
- Vacuum Leaks - Did you use a vacuum gauge? You said that 4 months ago, the ECU threw an EGR code, but none since. I'm thinking your current problem might be within the vacuum lines AFTER the EGR valve. The hoses that are most prone to deteriorate are those that are subjected to the most heat. Be sure to especially check all hoses that are closest to the exhaust, as well as all hoses at or near the PCV.
- MAF Sensor - You cleaned it with Windex? I would have never used Windex - only an electronic cleaner. Hope you didn't damage it.
- Oxygen Sensor - It could be that you have a bad 02, but feel this is doubtful since you're throwing codes in 2 banks.
< Message edited by Malibu Barbie -- 12/17/2006 12:15:41 AM >
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RE: 95 Crown Vic intermittent coding P0171 and P0174 (L... - 12/17/2006 4:16:45 PM
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Bob Wells
Posts: 4
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Joined: 12/9/2006
Status: offline
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ORIGINAL: Malibu Barbie
Thank You for the detailed , helpful reply Barbie.
Welcome, Bob! There's several different things than can cause your lean air/fuel mixture problem. Here's the areas I'd like to address to try to help you:
*Air Filter - When was the last time it was replaced?
about 4 months ago. It still looks pretty decent
*Bad fuel pump? Yes, that's possible, as well as a leaking FPR. When the fuel pump starts to go bad, it'll usually make a constant buzzing noise - have you heard anything unusual? Also, did you use a fuel pressure gauge to check the pressure at idle while the engine is warm?
No buzzing or other noises from fuel pump.
*FPR (fuel pump relay?) replaced four days ago, no difference.
Yes I measured fuel pressure several times with engine warm, always 31 psi. Compared it to my 1997 Town Car which was 32 psi.
*Fuel Injectors? How old are they?
Not sure, they might be the originals. How do i know for sure?
*Are they leaking?
Not that I can see.
*Have you tried using a fuel additive to clean the injectors? Remember that you usually have to run a full tank of gas with the additive before *you get the best results.
Two tanks with Chevron Fuel system/injector cleaner, no difference.
*Vacuum Leaks -
*Did you use a vacuum gauge?
I have a vacuum gauge but have not used it yet. Very good idea! I assume I tee in at different places and wiggle the associated hoses and fittings.
*You said that 4 months ago, the ECU threw an EGR code, but none since. I'm thinking your current problem might be within the vacuum lines *AFTER the EGR valve. The hoses that are most prone to deteriorate are those that are subjected to the most heat. Be sure to especially *check all hoses that are closest to the exhaust, as well as all hoses at or near the PCV.
I'll give close scrutiny to the hoses after the egr.
New PVC, no difference, fit in boot was fairly snug. Hose looked to be in good shape. I will have a closer look.
Oh WOW I just looked at the hose going from the pcv and followed it back to the base of the air intake and guess what I found!!!!
A big fat puncture or dry rot hole. I will repair and post back the results. Thanks a million Malibu Barbie!
*MAF Sensor - You cleaned it with Windex? I would have never used Windex - only an electronic cleaner. Hope you didn't damage it.
I read online in two places that Windex was ok. Only electronic cleaner I had contained lubricant, a no-no. I sprayed it with Windex until it was pristine clean, then used spray bottle with distilled water to rinse it and then air blew it dry. Engine ran very smooth and strong after that but still
had periods when it went into stumble/power loss mode.
*Oxygen Sensor - It could be that you have a bad 02, but feel this is doubtful since you're throwing codes in 2 banks.
Same thinking here
Thank You,
Bob
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RE: 95 Crown Vic intermittent coding P0171 and P0174 (L... - 12/17/2006 7:29:09 PM
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Malibu Barbie
Posts: 109
Score: 0
Joined: 12/7/2006
Status: offline
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quote:
ORIGINAL: Bob Wells
*You said that 4 months ago, the ECU threw an EGR code, but none since. I'm thinking your current problem might be within the vacuum lines AFTER the EGR valve. The hoses that are most prone to deteriorate are those that are subjected to the most heat. Be sure to especially check all hoses that are closest to the exhaust, as well as all hoses at or near the PCV.
Oh WOW I just looked at the hose going from the pcv and followed it back to the base of the air intake and guess what I found!!!! A big fat puncture or dry rot hole. I will repair and post back the results. Thanks a million Malibu Barbie!
Awesome, Bob! I'm anxious to find out how she runs after you replace that hose and whether she still throws any codes.
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RE: 95 Crown Vic intermittent coding P0171 and P0174 (L... - 12/17/2006 9:00:55 PM
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Bob Wells
Posts: 4
Score: 0
Joined: 12/9/2006
Status: offline
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quote:
ORIGINAL: Malibu Barbie
quote:
ORIGINAL: Bob Wells
*You said that 4 months ago, the ECU threw an EGR code, but none since. I'm thinking your current problem might be within the vacuum lines AFTER the EGR valve. The hoses that are most prone to deteriorate are those that are subjected to the most heat. Be sure to especially check all hoses that are closest to the exhaust, as well as all hoses at or near the PCV.
Oh WOW I just looked at the hose going from the pcv and followed it back to the base of the air intake and guess what I found!!!! A big fat puncture or dry rot hole. I will repair and post back the results. Thanks a million Malibu Barbie!
Awesome, Bob! I'm anxious to find out how she runs after you replace that hose and whether she still throws any codes.
Hello Barbie,
Please see pics in post above. After 70 miles of varied driving she is code free. Lately she had been throwing codes consistently after 5 to 10 miles so I'm very hopeful. She also runs very smooth and stronger than before. Thanks so much for getting me to take a second look!
Thank You!
Bob
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That's great news, Bob! I'm glad we were able to help you.
