Tracking down root cause of p1132/ p0300/ p0172 | Ford Explorer Forums - Serious Explorations

  • Register Today It's free!

Tracking down root cause of p1132/ p0300/ p0172

JustAnotherMember7

Active Member
Joined
May 12, 2020
Messages
57
Reaction score
19
City, State
Twin Falls
Year, Model & Trim Level
2001 Explorer XLS
It has been a while but I wanted to ask a few more questions/ run data past another set of eyes. Since my last post, I took the explorer out of use last july and purchased an f150 for work. I am wanting to fix my issue with the explorer and have a few more resources to go on than before. Originally, I was getting a p0172 code, then during a several hour drive last year the truck began to run rough at idle and while driving and threw a p0300 code. I put a fresh set of plugs and wires in, cleared the codes and got the explorer home. The explorer has 150,000 miles on it, and had a remanufactured engine installed at 138,000 miles. No other PCM related codes to go off of.

Upon reconnecting the battery last week, and getting Forscan hooked up for a key on engine running self test, I could hear a hissing from the rear of the engine, and the test set this code:

Diagnostic Trouble Code (DTC) Descriptions
P1132 - Lack of HO2S-11 Switch, Sensor Indicates Rich

This the only current PCM related code the vehicle is reporting currently. I read fuel pressure which stayed at 62 PSI idle and 60 PSI at 1/2 throttle, checked vacuum hoses, and inspected for any obvious problems. After driving the vehicle a few miles for data, I sprayed carb cleaner to look for leaks, checked with soapy water, and still haven't found any obvious leaks. I disassembled the upper and lower intake manifold to check the manifolds for cracks, and get a better understanding about where the vacuum lines go, and found small foldable heatshield panels in the valley underneath the lower intake manifold, the heat shield adhesive had melted off the back, and down into a soupy mess mixed with twigs from what looked to be a small nest in the valley. I have removed as much as I could, then installed the manifolds with new gaskets to get the explorer out of the garage. While the manifolds were out, I checked the injectors for resistance and came up with .014 ohms when measuring at 2000ohms, all injectors were the same. After reinstalling everything I also probed each injector with a screwdriver and heard a even tick tick noise.

Since I heard the vacuum leak at the back, I suspect the pcv valve ( which looked clean and still rattled), or the breather it is attached to has cracked and started to leak due to the adhesive pooling around it, or the plastic port the injectors go into. So my next plan of attack is to get a smoke machine and smoke the intake, I will also check electrical connections to see if there is a short or electrical fault.

What would you guys do next based off of this data?

INCLUDED LIVE DATA


Short term fuel trim, long term fuel trim, engine coolant temp, engine load, RPM, Misfire detected, O2 Sensor 1 (upstream and downstream), O2 Sensor 2 (upstream and downstream)

Pic 1 Battery Connected 1st Idle test , Pic 2 Driving test
1 IDLE TEST.jpg
2 Drive Test.jpg


Pic 3 Driving Test Closeup , Pic 4 Idle Test After Driving
3 Drive Test Closeup.jpg
4 IDLE TEST AFTER DRIVING.jpg


Pic 5 Idle Test After Restarting Engine, Pic 6 PC/ED Manual DTC Explanation (See P1130)
5 IDLE TEST ENGINE RESTARTED.jpg
Diagnostic Manual.jpg
 



Join the Elite Explorers for $20 each year.
Elite Explorer members see no advertisements, no banner ads, no double underlined links,.
Add an avatar, upload photo attachments, and more!
.





Def smoke test it, and check your hoses/lines.

When it idles, does it surge?
 












@JustAnotherMember7 Is that live data from Forscan? I don't have mine working yet and just curious...
 












Check for collapsing hoses. I had a hose (I think it was IAC?) that got soft and collapsed under vacuum, causing surging idle
 






Check for collapsing hoses. I had a hose (I think it was IAC?) that got soft and collapsed under vacuum, causing surging idle
So, I just got done with the intake smoke test and found a cracked hose going from the crankcase to the intake duct.

I also found that the bottom of the EGR valve has smoke pouring out of it into the engine bay (not from the vacuum line going to the egr valve).

this test was done with the engine off.

So I'll fix the hose, but what about the EGR valve?

EDIT: It looks like smoke coming out of EGR valve with engine off means the diaphragm is shot, so first items to address before checking for DTC again would be replace the EGR Valve, and Replace cracked crankcase tube (second bypass tube some explorers had to the intake). Interesting that the computer wouldn't throw a DTC related to the EGR valve, but instead P0172
 






I'm old, not old enough to retire yet, but old enough to be "old school". We didn't have sensors and PCMs and other types of car computers to deal with when we were working on cars with carburetors and points, so I don't know if I would be of much help. However, something makes me think you might have one or more of your O2 sensors malfunctioning. It is a bit of a pain to remove your oxygen sensors especially without a lift to raise the vehicle. For sure it would require a special socket to remove, intact, an O2 sensor. Amazon, Ebay, Harbor Freight all sell them. link to HF below.
Also a link to a video testing O2 sensor

I hope this helps. Maybe someone that knows more will chime in.
 






Only thing that makes me think it isn’t a bad oxygen sensor is that both upstream sensors immediately went high voltage. To me, that’s some type of systemic issue.

What’s interesting about the 1132 is that the sensors stop switching, and are stuck at high voltage (rich/low oxygen) but the book says the system is correcting for an over-lean condition.

I’m no EFI engineer, but my brain doesn’t understand that. But, assuming the book is correct, it could very well be that leaking EGR valve and/or other vacuum leaks. I’d fix them, re-smoke the system (now that those big holes are fixed, the small ones will show), fix those, clear the codes, and see what happens.
 






Only thing that makes me think it isn’t a bad oxygen sensor is that both upstream sensors immediately went high voltage. To me, that’s some type of systemic issue.

What’s interesting about the 1132 is that the sensors stop switching, and are stuck at high voltage (rich/low oxygen) but the book says the system is correcting for an over-lean condition.

I’m no EFI engineer, but my brain doesn’t understand that. But, assuming the book is correct, it could very well be that leaking EGR valve and/or other vacuum leaks. I’d fix them, re-smoke the system (now that those big holes are fixed, the small ones will show), fix those, clear the codes, and see what happens.
Hey, So I went ahead and fixed the vacuum leak on the intake, replaced the EGR valve, and replaced a split hose going to the DPFE sensor. I took the old EGR off and put it under vacuum and the valve lifted, so perhaps carbon was stopping the valve from sealing all the way. I disconnected the battery and reset learned adaptations.

Ran an idle test and drive test and It performed worse than before (Bank 1 Short term fuel trim of -22% and long term around -12% at idle, the other bank was within +-3%. Seeing this, I went back to the PC/ED manual and went through P1132 symptom charts this time without the P0172/ P0300 code present and came to a test to Isolate the MAF from the trouble code diagnostics, as per the test I disconnected the MAF sensor and drove the vehicle a few miles, Idle improved drastically, and the vehicle has power again. I suspect that when I was firing the parts cannon, and replaced the MAF sensor, that there is some design difference between OE and Bluestreak, I will put the OE one back in and do a engine running self test again. As well as another smoke test.

Thoughts?

*EDIT: P1132 Code set again during Key on engine running self test after EGR replacement*

Voltage PID from MAF at hot idle range is supposed to be 0.7-0.9 volts, and live data came back at 0.7-1.0 volts

Barometric pressure PID should be within 2 inches mercury of my area (30 inHg) live data is 28inHg.
 






A few things with these near antique vehicles, rubber gets soft, plastic gets brittle, wires break. Trace every vacuum line, I found breaks in places never expected. Get a mighty vac pump and draw a vacuum on each section and see that it holds. Check out this thread: 2001 5.0 Eddie Bauer Vacuum Diagram is Unobtanium!
 






Next, consider the age of the sensors on the vehicle, if they're original, test for proper resistance and operation. If they're problematic replace, and the wiring to and from the sensor to the computer must be verified as good (check continuity, resistance, manipulation of wires while testing to reveal breaks). I had an EGR solenoid fail and take out my PCM, replace that just because it's old for preventative maintenance. I've replaced most of my sensors while chasing similar problems, I didn't have a problem with that as the we're old/original. Not the best troubleshooting approach, but having new helps. Clean all the ground connections, add copper anti seize for better conductivity. 2001 Explorer 5.0 P0174 Code
 






Replace the plastic hoses with rubber vac line. Don’t waste your time inspecting them
 






@JustAnotherMember7 I was looking for something that I read a few weeks ago about sensors that are slow to respond causes the PCM to throw trouble codes, DTCs. There are people out there that can access the parameters in many PCMs and "slow down" their reporting so that it wont store a DTC and leave the check engine light on. I couldn't find that but I found this.
PCMs sensors etc
 






@JustAnotherMember7 I was looking for something that I read a few weeks ago about sensors that are slow to respond causes the PCM to throw trouble codes, DTCs. There are people out there that can access the parameters in many PCMs and "slow down" their reporting so that it wont store a DTC and leave the check engine light on. I couldn't find that but I found this.
PCMs sensors etc
Thanks for the articles and advice!

So I got a chance to smoke test the explorer again, no leaks. This was also the first day with 60 degree weather up from freezing, which is also where I noticed the issue worsened the last few years. I've read up on fuel trims some, watched a few videos, cleaned and reinstalled the factory MAF sensor and reset KAM. Lo and behold the engine was shuddering like it was in the north pole naked. I will also note the same goopy adhesive from the heat shield was found on B1S1 o2 sensor which may be interfering with outside air measurement. But this vehicle also has 150k on the odometer. Self test for p1132 also pops up with original MAF installed.

Long term Idle Fuel trim for bank one was -22.66% and bank two was 6.5%, it looks like B1S1 o2 sensor is sticking rich, and causing the engine to take away fuel, causing the VERY rough idle. Every other check BESIDES base engine timing has been checked and passed. So I've ordered Motorcraft upstream o2 sensors. I believe the sensor has failed because it is reading outside of normal range, switches slower while staying rich and If I make a large vacuum leak / increase rpms the sensor does not switch to lean, so the computer can add fuel to get back to stoichiometric.

I'll update you guys when I get the sensors installed.
 






Next, consider the age of the sensors on the vehicle, if they're original, test for proper resistance and operation. If they're problematic replace, and the wiring to and from the sensor to the computer must be verified as good (check continuity, resistance, manipulation of wires while testing to reveal breaks). I had an EGR solenoid fail and take out my PCM, replace that just because it's old for preventative maintenance. I've replaced most of my sensors while chasing similar problems, I didn't have a problem with that as the we're old/original. Not the best troubleshooting approach, but having new helps. Clean all the ground connections, add copper anti seize for better conductivity. 2001 Explorer 5.0 P0174 Code
Good advice! Definitely will verify the wires to PCM are good for o2 sensors and that there is no short or open connection. Although there is a reason I got into plumbing instead of being an electrician haha, much easier to understand!
 






@JustAnotherMember7 I was looking for something that I read a few weeks ago about sensors that are slow to respond causes the PCM to throw trouble codes, DTCs. There are people out there that can access the parameters in many PCMs and "slow down" their reporting so that it wont store a DTC and leave the check engine light on. I couldn't find that but I found this.
PCMs sensors etc
Hey allmyEXes, since you mentioned slow responding sensors, I took a look at switching of the old vs new o2 sensors and they are much snappier. Looks like the high negative fuel trim problem has been solved. Now I just have the slightly rough idle instead of a shaking idle. No DTCs with Key on engine running self test now, but my ex does stall consistently at the end of the test (when rpm is dropped down to 500 rpm).

The OEM maf sensor does switch a little slower than I'd like, and grabbing a junkyard sensor to compare data with may be useful. The aftermarket new sensor reports lower readings than what the hot idle value is supposed to be, and seems to make the problem worse. So I believe that can be chalked up to the hot wire being in a different position than oem. Disconnecting the MAF sensor and running the engine has no improvement change like before, but very smelly fuel comes out of the tail pipe then and the computer strategy runs the engine rich ( 0.97v b1s1 and b2s1).

Looks like bank 1 now adds 5-8% more fuel than bank 2, so Next plan of attack is to use up the old gas in the tank, seafoam the engine, and clean the injectors and see how everything responds then. Onto the body dtcs after that.

Edit: With MAF connected wide open throttle feels limited, with MAF disconnected there is some* more power and acceleration.
 






@justanothhermember I'm not hardly a EFI/PCM guy however if your fuel is old, over six months old, it would also be out of season. My common sense tells me that a fuel issue would cause your test results to be a bit erroneous. I haven't read all that you have been through with this engine and system, but I have two questions here in my limited time. How many miles are on the engine and have you performed a simple compression test? Uneven compression could cause a miss or two of a sort. If the engine has been sitting for some time, cleaning and or replacing the injectors might not be a bad idea. Test the injectors first though so that you are not just throwing money at the wrong problem.
My '97 5.0 has been sitting for 39 months since its initial problem and then I ran it 6 months later. So since my upper intake is currently removed, I'm going with new injectors. I'm going to test the new ones before installing so that I don't install a faulty new one. I wish that I had time to work on my project. Work responsibilities and lack of project funds are preventing me from it.
 






@justanothhermember I'm not hardly a EFI/PCM guy however if your fuel is old, over six months old, it would also be out of season. My common sense tells me that a fuel issue would cause your test results to be a bit erroneous. I haven't read all that you have been through with this engine and system, but I have two questions here in my limited time. How many miles are on the engine and have you performed a simple compression test? Uneven compression could cause a miss or two of a sort. If the engine has been sitting for some time, cleaning and or replacing the injectors might not be a bad idea. Test the injectors first though so that you are not just throwing money at the wrong problem.
My '97 5.0 has been sitting for 39 months since its initial problem and then I ran it 6 months later. So since my upper intake is currently removed, I'm going with new injectors. I'm going to test the new ones before installing so that I don't install a faulty new one. I wish that I had time to work on my project. Work responsibilities and lack of project funds are preventing me from it.
Quick update, so I ran the sea foam in the intake, gas tank, and 5oz in the oil (will change the oil next week) and it is running smoother than it ever has before. The slight shudder at idle is still there (drops down to 500 rpm occasionally and under load) but the build up of issues has been whittled down. Fuel injectors still need to be swapped with other clean set. Idle goes down to 400rpm with IAC disconnected, before the sensors were changed it would stall when wire harness was disconnected, big improvement!!

With the vehicle put back into service today I noticed that heat only comes out of the defrost. As it turns out this occurs when there is a vacuum leak to the HVAC system / vacuum reservoir ball. This is probably why I am seeing positive fuel trim now and makes sense because when I smoke tested it again, I saw very faint wisps coming from the intake air box which I assumed was seepage past my rubber glove plug but must be from the vacuum lines / ball underneath it.
 



Join the Elite Explorers for $20 each year.
Elite Explorer members see no advertisements, no banner ads, no double underlined links,.
Add an avatar, upload photo attachments, and more!
.





My '97 5.0 has been sitting for 39 months since its initial problem and then I ran it 6 months later. So since my upper intake is currently removed, I'm going with new injectors. I'm going to test the new ones before installing so that I don't install a faulty new one. I wish that I had time to work on my project. Work responsibilities and lack of project funds are preventing me from it.
It would be cool to have you show your progress on your 5.0 or do a video on your vehicle! Ever considered supercharging it?

I have a factory service manual if you need me to look anything up feel free to ask.
 






Back
Top