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#4120664 - 09/12/21 02:51 PM New to me '00 P-71 and the P0172 mystery........
lance54r Offline
n00b

Registered: 08/28/21
Posts: 11
Loc: SE TX
Thanks for having me onboard, please enjoy the saga. Someone nearby sold me a 2000 P71 with 47k original miles. It is in great shape for it's age. It was never a patrol car and has grey cloth interior and carpet. It's not perfect, the car has a fair amount of sun damage. The story is that it was operated in a small east Texas town by the local Judge. After he was done with it the car sat for years until it was bought by a local dealer that "replaced the entire fuel system" because of the old gas. He then sold it to the guy I bought it from. The autocheck report on the car aligns with the story.

So I own the car one day and it throws a P0172. I took it to my mechanic and they where confused. They said "the ECU VIN didn't match the vehicle and it looks like alot of other parts parts have been changed." They reset the CEL and suggested I start by changing the fuel injectors since they were probably leaking.

Because I have more time than money I brought the car home to DIY it. My buddy and I did a leak down test on the fuel rail schrader valve and it failed miserably. The pressure was 33-35 lbs running. We pulled the vacuum line on the FPR and it went up approx 10 lbs. We put the vacuum line back on and turned off the engine and the pressure went to zero in about 30 seconds. Easy enough, I ordered 8x AUS remanned Ford injectors.

We installed them yesterday. Seven of the old injectors were Mostplus brand. The one under the crash bracket had never been changed. BTW, I'm not a fan of that @#$!! crash bracket. I googled the reviews on Mostplus injectors and it wasn't flattering. With the new injectors the car did great on the leak down, it's alot easier to start warm and it seems to have a little more pep.

I drove the car about 5 miles and the CEL P0172 popped on. I just cleared it hoping it is a left over from the old injectors.

And here we are.....anybody else have an ideas? I am told the plugs and packs have been changed recently and my mechanic tried a new MAF but it made no difference so they put it back the way they found it.
_________________________
2000 P71(Non-patrol car), 47,000 mi.

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#4120672 - 09/12/21 04:47 PM Re: New to me '00 P-71 and the P0172 mystery........ [Re: lance54r]
ironmarinebill64 Offline
Rookie

Registered: 01/30/21
Posts: 54
Loc: New York, USA
P0721 is a rich condition.

You say the different MAF made no difference. Just spit ballin' but how's the water temp? A bad thermostat or temperature sensor could tell the PCM that it's still in "choke" mode.

If you have a scan tool, I'd also suggest seeing what the fuel trim difference between the banks. If the driver's side (bank 2) is okay, as P1072 is Bank 1 rich, are there any things that stand out in terms of "fixes" between the two sides (DIY hoses and clamps, cracked EGR or vacuum lines...with an used or auction fleet car, the possibilities are endless).

The other typicals of a P0172 are O2 sensors and wrong heat range or worn plugs.

Good luck brother
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1999 Mercury Grand Marquis (gave that to youngest son, and he's now a converted true believer)

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#4120678 - 09/12/21 06:31 PM Re: New to me '00 P-71 and the P0172 mystery........ [Re: lance54r]
Bangster Offline

Poobah

Registered: 11/30/01
Posts: 9555
Loc: Tucson Az
Since it is only one bank with an issue, and it is bank 1, which is the passenger side, I would be looking for something that is not shared between bank 1 and 2.

It thinks there is too much fuel, and tries to lower the amount of fuel, but is unable to and sets the CEL.

Do any of the spark plugs in the passenger side look significantly different than the others, or have raw fuel on it? Do you get a smell of fuel in the oil?

If it was me, I would check the plugs, try a noid light to see that each injector is firing (one isn't on solid), then it could be the bank 1 upstream o2 sensor, if you can data log and see if it is stuck at a high voltage or if it varies.
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00 Grand Marquis LS Premium - 97 Cougar 4.6 Sport - 89 Cougar LS - 63 Falcon 302 - 82 F-150 - 97 Mark VIII LSC - 2017 Escape SE - 2012 Fusion Sport AWD

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#4120686 - 09/12/21 07:19 PM Re: New to me '00 P-71 and the P0172 mystery........ [Re: lance54r]
lance54r Offline
n00b

Registered: 08/28/21
Posts: 11
Loc: SE TX
I'm not familiar with alot of these numbers on the OBD2 reader, but here they are. The car was at idle and the temps were in the normal operating range and using an Innova 5210 reader....

Fuel Sys 1........... CL
Fuel Sys 2........... NA
Calc Load ........... 32.5%
ECT ................. 187 f
STFT B1.............. 22.7%
LTFT B1.............. -24.2%
STFT B2.............. -25.0%
LTFT B2 ............. -21.1%
Engine RPM .......... 809
Spark Adv............ 23.0 degrees
IAT ................. 126 f (91f outside!)
MAF.................. 0.79 lb/min
TPS.................. 18.8%
O2S B1S1.............0.240v
STFT B1S1............1.6%
O2S B1S2.............0.420v
O2S B2S1.............0.505v
_________________________
2000 P71(Non-patrol car), 47,000 mi.

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#4120756 - 09/13/21 01:54 PM Re: New to me '00 P-71 and the P0172 mystery........ [Re: lance54r]
hkerekes Offline
Member

Registered: 09/19/20
Posts: 142
Loc: NC
You have a way of checking the fuel pressure? Those trims are not ideal.

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#4120760 - 09/13/21 02:08 PM Re: New to me '00 P-71 and the P0172 mystery........ [Re: hkerekes]
RF_Overlord Offline

Poobah

Registered: 12/14/02
Posts: 7676
Loc: MA
Originally Posted By hkerekes
Those trims are not ideal.

My vote for understatement of the year.

You've got B1 slammed all the way lean and B2 slammed all the way rich...unless there's a typo and you're missing a minus sign.
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'00 Grand Marquis GS (Silver)
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#4120770 - 09/13/21 04:15 PM Re: New to me '00 P-71 and the P0172 mystery........ [Re: RF_Overlord]
hkerekes Offline
Member

Registered: 09/19/20
Posts: 142
Loc: NC
Originally Posted By RF_Overlord
Originally Posted By hkerekes
Those trims are not ideal.

My vote for understatement of the year.

You've got B1 slammed all the way lean and B2 slammed all the way rich...unless there's a typo and you're missing a minus sign.


Yeah he has to have missed the - sign. Will it even let the short and long term be 40% off?

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#4120772 - 09/13/21 04:23 PM Re: New to me '00 P-71 and the P0172 mystery........ [Re: lance54r]
lance54r Offline
n00b

Registered: 08/28/21
Posts: 11
Loc: SE TX
The fuel pressure at the rail is +35 lbs and it rises about 10 lbs when I pull the vacuum off the FPR. The new injectors held 30 lbs for over 10 minutes after shut down.

It is a typo, or better yet it's "operator error". Those numbers are the first ones I got on a new OBD reader. However the LTFT's were running at -24% (bank 1) and -21% (bank 2). But I never erased the KAM after putting in the new injectors.

My next step is to hard reset the ECM to clear the KAM and run it about 30 miles on the highway. Hopefully this will allow the fuel trims to be relearned with the new injectors and get the cats up to temp to help burn some carbon.
_________________________
2000 P71(Non-patrol car), 47,000 mi.

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#4120782 - 09/13/21 07:49 PM Re: New to me '00 P-71 and the P0172 mystery........ [Re: lance54r]
hkerekes Offline
Member

Registered: 09/19/20
Posts: 142
Loc: NC
you sure those are the correct injectors? they could be bigger than what the computer is expecting and creating the rich condition.

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#4120792 - 09/13/21 09:31 PM Re: New to me '00 P-71 and the P0172 mystery........ [Re: lance54r]
lance54r Offline
n00b

Registered: 08/28/21
Posts: 11
Loc: SE TX
The new injectors are good. Ford OEM remanned by AUS. I cross checked the part number against Ford. Seven of the previous ones were junk made in china. A full set of eight are available on Amazon for the low, low price of $69, only $8.66 each. The one under the crash bracket was never changed.
_________________________
2000 P71(Non-patrol car), 47,000 mi.

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#4120868 - 09/14/21 06:08 PM Re: New to me '00 P-71 and the P0172 mystery........ [Re: lance54r]
lance54r Offline
n00b

Registered: 08/28/21
Posts: 11
Loc: SE TX
VICTORY!!
I did a hard reset on the ECM to clear the "keep alive memory". After hooking the battery back up I followed the Ford instructions for "relearning" the ECM after a battery disconnect. This was followed by a 30 mile highway drive for the ECM and also to get the cats good and warm. The results are that with a steady throttle the LTFT's were mostly 0.0 to 0.8 on both banks. I got up to 2.7 by goofing off.

What next? I gotta fix the inoperative front passenger window smile
_________________________
2000 P71(Non-patrol car), 47,000 mi.

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