Codes P0172 and P0175, engine running rich?

Tiny
VANS89
  • MEMBER
  • 1996 FORD E-SERIES VAN
  • 5.8L
  • V8
  • 2WD
  • AUTOMATIC
  • 180,000 MILES
Hello,

The van listed above is an E250. The engine light is on and won't pass smog. Pulled the codes P0172 and P0175 (running rich?). I did take it to a mechanic for a diagnostic and they told me it was the purge solenoid. I paid for the part installed and still have the same problem.

symptoms: Starts up like a champ, when warm it seems sluggish hard to keep it at 65 MPH seems like its struggling. Runs okay at 55 and below. It has stalled before (even seems like its missing when at idle until I give it gas). I do see black smoke coming out of the exhaust when at idle. With the throttle wide open is runs okay. Still seems sluggish.

I've also replaced the following:

Fuel regulator
Fuel filter
MAF sensor
New air filter
New spark plugs
New air filter
Fuel pump read 30 PSI at idle
Purge solenoid

Anything else I should check?

Next, I plan on replacing the rubber hoses to the purge solenoid as they look corroded. Also, I noticed that the PCV grommet that fits on the right side of the valve cover is unsealed. I'm trying to figure out a way to replace this as its underneath the air intake. Do I have to take off the entire intake just to replace the pcv valve grommet? Anyone know a better way? Can this be the reason the motor is running rich?

Any help would be much appreciated.
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Wednesday, August 24th, 2022 AT 7:16 PM

11 Replies

Tiny
KEN L
  • ADMIN
I bet the cause for the engine's running rich is a partially clogged catalytic converter. This will cause the PCM to think the engine is under load (low vacuum) and dump more fuel even though there is no load. This guide can help you confirm this is the issue:

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

Please run down this guide and report back.
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Thursday, August 25th, 2022 AT 12:48 PM
Tiny
VANS89
  • MEMBER
Thanks for getting back to me, I ran down the list right now. Results are below.

Temperature readings

1st reading
1st cat 2nd cat
Inward 350 F 451 F
downward 451 F 421 F

2nd reading
1st cat 2nd cat
Inward 338 F 412 F
Downward 320 F 308 F

Ran motor without upstream 02 sensors
It sounded like a Harley, It didn't sputter or anything at idle. As far as power it seemed the same when I drove it around the block

Vacuum pressure gauge
It was at 21", with the quick rev at the throttle the dial dropped to zero for a split second and went back to 21"

kept it at an rpm for about 15 seconds and the vacuum rose to 23 " then dropped to 21"

According to the temp test maybe my second cat is partially clogged? The other tests seem as though it passed.
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Saturday, August 27th, 2022 AT 6:46 PM
Tiny
KEN L
  • ADMIN
Yep, the second cat seems partially plugged which will cause the issue. The power will be about the same with the sensor out because the hole is too small to let the exhaust out enough to see a difference. Also, the MAP/MAF sensor is still reading low vacuum. It could be caused by a stuck injector on the #2 side of the cat, I would remove the spark plugs on that side to see if one looks different than the rest.
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Monday, August 29th, 2022 AT 12:30 PM
Tiny
VANS89
  • MEMBER
The vacuum seemed as though it was where it was supposed to be according to the test 21 " at idle, held at 23" with an RPM of 2.500 or so. It only dropped to zero when I did a quick rev. Is it still considered low? Or should I re-do the test to confirm?

Also, wouldn't the computer throw a code if a fuel injector was faulty?

I'll take a look at the spark plugs as soon as I get a chance.

Thank you for the help thus far. Any more info is much appreciated.
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Monday, August 29th, 2022 AT 9:52 PM
Tiny
KEN L
  • ADMIN
The computer can only see the electrical portion of the injector not the mechanical valve part. Let me know what the spark plugs look like. The vacuum reading looks okay at idle, you can redo the test when the engine is under load it might tell us more.
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Tuesday, August 30th, 2022 AT 1:10 PM
Tiny
VANS89
  • MEMBER
I checked the plugs on bank 2. They were replaced a year ago. They look okay, a little white at the ends meaning maybe overheating a little. I tried attaching an image not sure if its showing.

Also, I tried the old screwdriver to fuel injector trick, they all seem to be working.
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Sunday, September 11th, 2022 AT 9:44 PM
Tiny
KEN L
  • ADMIN
Okay, they look the same, can I ask if there is an exhaust leak on bank 2?
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Monday, September 12th, 2022 AT 6:41 PM
Tiny
VANS89
  • MEMBER
There's no exhaust leak that I could see.

I also wanted to point out that when the first check engine light came on it was the codes P0171 and PO174 (lean). I found the throttle body hose out to the purge solenoid was withered (Purge solenoid replaced later) I went ahead and replaced it, but the engine light remained on. When I checked the codes and tried to fix (sometime later) the codes changed to p0172 and p0175 (running rich).

Is it worth replacing the two catalytic converters? It's about $500.00 for all of it but the exhaust has to be welded.
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Monday, September 12th, 2022 AT 9:52 PM
Tiny
KEN L
  • ADMIN
Before we do that lets runt eh vacuum leak test again with the engine cool. here is a guide to show you how, check the PVC line these vans had a problem with them:

https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

Please go over this guide and report back.
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Tuesday, September 13th, 2022 AT 9:23 AM
Tiny
VANS89
  • MEMBER
I haven't done the vacuum leak test again yet, but I did notice this. The pic is attached. This looks like the EGR valve. It is connected to the intake manifold. The bottom connection from the EGR valve is to the valve cover. The rubber connection to the valve cover is broken. Exposing the top of the valve cover (oil leakage). I'm not even sure what the part is or how to repair it. If you happen to know what is let me know. This can't be good for vacuum?
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Wednesday, November 9th, 2022 AT 9:00 PM
Tiny
KEN L
  • ADMIN
Yep, this is not good, the grommet needs to be replaced which should pull out of there using a large flat blade screwdriver. Let me know what happens please.
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Friday, November 11th, 2022 AT 1:55 PM

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