Lean Codes and EVAP Woes
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Member
Joined: Jan 2025
Posts: 46
Likes: 6
From: Stuttgart, AR
Lean Codes and EVAP Woes
Hello all,
Long time lurker, first time poster. Came into a '97 4.0 OHV 2wd a month and a half ago (69k original miles if you could believe it! Up to high 71k now) and I love it! Got some dreaded codes though that weren't on the truck when I bought it...
I've seen many a thread like this and am about to tear my hair out trying to solve the issue. Any help would be much appreciated. I'm sort of new to wrenching and fixing my own problems but am willing to learn!
Codes:
Any thoughts? I'm all ears
Long time lurker, first time poster. Came into a '97 4.0 OHV 2wd a month and a half ago (69k original miles if you could believe it! Up to high 71k now) and I love it! Got some dreaded codes though that weren't on the truck when I bought it...
I've seen many a thread like this and am about to tear my hair out trying to solve the issue. Any help would be much appreciated. I'm sort of new to wrenching and fixing my own problems but am willing to learn!
Codes:
- P1443 - EVAP Control System Purge Valve Malfunction
- P0171 & P0174 - Bank 1 & 2 "Too Lean" (I put this in quotes since I know it's the computer calculating it that way, may not be the actual case)
- P0153 & P1151 - Bank 1 O2 Sensor codes. I have a new one on the way and will replace it. Had the same with Bank 2 a while back but resolved the issue by replacing the sensor on that bank
- Noticed that fuel leaks when filling up and get to full. I believe it to be the filler neck and will replace it along with the fuel pump. Previous owner left lots of old gas in there with no stabilizer.
- O2 sensors as stated above
- Have not noticed any vacuum leaks but am going to get it smoke tested (hopefully) this week
- PCV Valve/Hose are on the way for replacement, but the current one doesn't sound bad. Figured it's cheap enough to replace anyhow since it all looks OEM right now
- MAF cleaned, flowrate 3.88-4.00 g/s @ idle
- Engine RPM @ ~1200 when cold but comes back down to 800-900
- Fuel Pressure goes to 30-40psi @ key on engine off, but falls to ~10psi in a hurry when everything is shut off
- Fuel Filter replaced at ~70k
- Spark plugs & wires replaced (autolite double platinum & the basic wires at O'Reilly)
- If I remember correctly, IAC unplugged seems to let idle drop off, but engine does not stall. You can tell it's chugging though (can always do this test again if y'all like)
Any thoughts? I'm all ears
Member
Joined: Sep 2019
Posts: 1,193
Likes: 182
From: Hackensack, Nj
Please tell us you have a scanner and are not going to a parts store repeatedly for code reading.
I too bought a low mileage Ranger from a neighbor.
What's the overall condition of the truck? Garage kept...battery new/old...tire condition/age...raccoons in the cab?
How's the coolant look? Have you cranked the spare tire down yet?
I'm not certain but the EVAP Control Valve MIGHT be easily accessible on the radiator support.
See if it's there. Maybe that simple repair can buy you breathing time to assess the EVAP system.
O2 sensors, at 29 MY of age, are well beyond the 10yr/100k mile lifespan.
Replacing all 4 with Motorcraft parts might be smart.
If the fuel pressure has been building back up "instantly", maybe the drop to ~10psi upon shutdown is something you can live with?
I understand the system is supposed to hold pressure. Does it effect starting?
With the EVAP questions you now have, maybe learning everything you can before possibly dropping the tank (removing the box) to do a pump is smart?
Maybe all the EVAP hosing atop the tank will need to go. You might need time to get the parts together.
Just for giggles, check the battery voltage some morning before you fire it up.
Do you have an electric meter?
My later Ranger(an '05) charges high for ~15 minutes after startup then drops to the usual 14.X charging voltage.
I don't know if your '97 has the "higher charging rate for the first 15 minutes" feature or not.
We all know the older vehicles aren't as finicky when faced with lower voltages, but it's still good to know the condition of your battery and charging system.
EX:
My Ranger started just fine when I purchased it from a neighbor. The battery was >6 years old.
The morning voltage was 10.2 volts. I had to wait a week for Group 59 batteries to be delivered to the store.
Overall, a good experience.
A fellow here urged Ranger owners to swap the coolant hoses at the heater core to slow pitting from within.
You might want to do a transmission pan-drop and filter change....just to know.
My fluid was 15 year old factory fill with only 48k on it. Still, it was dark. Yours might be much worse.
Ford has back-specked to Mercon V, even i f your dipstick says, "MERCON".
I bought a Dorman pan WITH a drain plug for future drain & fills.
I too bought a low mileage Ranger from a neighbor.
What's the overall condition of the truck? Garage kept...battery new/old...tire condition/age...raccoons in the cab?
How's the coolant look? Have you cranked the spare tire down yet?
I'm not certain but the EVAP Control Valve MIGHT be easily accessible on the radiator support.
See if it's there. Maybe that simple repair can buy you breathing time to assess the EVAP system.
O2 sensors, at 29 MY of age, are well beyond the 10yr/100k mile lifespan.
Replacing all 4 with Motorcraft parts might be smart.
If the fuel pressure has been building back up "instantly", maybe the drop to ~10psi upon shutdown is something you can live with?
I understand the system is supposed to hold pressure. Does it effect starting?
With the EVAP questions you now have, maybe learning everything you can before possibly dropping the tank (removing the box) to do a pump is smart?
Maybe all the EVAP hosing atop the tank will need to go. You might need time to get the parts together.
Just for giggles, check the battery voltage some morning before you fire it up.
Do you have an electric meter?
My later Ranger(an '05) charges high for ~15 minutes after startup then drops to the usual 14.X charging voltage.
I don't know if your '97 has the "higher charging rate for the first 15 minutes" feature or not.
We all know the older vehicles aren't as finicky when faced with lower voltages, but it's still good to know the condition of your battery and charging system.
EX:
My Ranger started just fine when I purchased it from a neighbor. The battery was >6 years old.
The morning voltage was 10.2 volts. I had to wait a week for Group 59 batteries to be delivered to the store.
Overall, a good experience.
A fellow here urged Ranger owners to swap the coolant hoses at the heater core to slow pitting from within.
You might want to do a transmission pan-drop and filter change....just to know.
My fluid was 15 year old factory fill with only 48k on it. Still, it was dark. Yours might be much worse.
Ford has back-specked to Mercon V, even i f your dipstick says, "MERCON".
I bought a Dorman pan WITH a drain plug for future drain & fills.
Thread Starter
|
Member
Joined: Jan 2025
Posts: 46
Likes: 6
From: Stuttgart, AR
Please tell us you have a scanner and are not going to a parts store repeatedly for code reading.
I too bought a low mileage Ranger from a neighbor.
What's the overall condition of the truck? Garage kept...battery new/old...tire condition/age...raccoons in the cab?
How's the coolant look? Have you cranked the spare tire down yet?
I'm not certain but the EVAP Control Valve MIGHT be easily accessible on the radiator support.
See if it's there. Maybe that simple repair can buy you breathing time to assess the EVAP system.
O2 sensors, at 29 MY of age, are well beyond the 10yr/100k mile lifespan.
Replacing all 4 with Motorcraft parts might be smart.
If the fuel pressure has been building back up "instantly", maybe the drop to ~10psi upon shutdown is something you can live with?
I understand the system is supposed to hold pressure. Does it effect starting?
With the EVAP questions you now have, maybe learning everything you can before possibly dropping the tank (removing the box) to do a pump is smart?
Maybe all the EVAP hosing atop the tank will need to go. You might need time to get the parts together.
Just for giggles, check the battery voltage some morning before you fire it up.
Do you have an electric meter?
My later Ranger(an '05) charges high for ~15 minutes after startup then drops to the usual 14.X charging voltage.
I don't know if your '97 has the "higher charging rate for the first 15 minutes" feature or not.
We all know the older vehicles aren't as finicky when faced with lower voltages, but it's still good to know the condition of your battery and charging system.
EX:
My Ranger started just fine when I purchased it from a neighbor. The battery was >6 years old.
The morning voltage was 10.2 volts. I had to wait a week for Group 59 batteries to be delivered to the store.
Overall, a good experience.
A fellow here urged Ranger owners to swap the coolant hoses at the heater core to slow pitting from within.
You might want to do a transmission pan-drop and filter change....just to know.
My fluid was 15 year old factory fill with only 48k on it. Still, it was dark. Yours might be much worse.
Ford has back-specked to Mercon V, even i f your dipstick says, "MERCON".
I bought a Dorman pan WITH a drain plug for future drain & fills.
I too bought a low mileage Ranger from a neighbor.
What's the overall condition of the truck? Garage kept...battery new/old...tire condition/age...raccoons in the cab?
How's the coolant look? Have you cranked the spare tire down yet?
I'm not certain but the EVAP Control Valve MIGHT be easily accessible on the radiator support.
See if it's there. Maybe that simple repair can buy you breathing time to assess the EVAP system.
O2 sensors, at 29 MY of age, are well beyond the 10yr/100k mile lifespan.
Replacing all 4 with Motorcraft parts might be smart.
If the fuel pressure has been building back up "instantly", maybe the drop to ~10psi upon shutdown is something you can live with?
I understand the system is supposed to hold pressure. Does it effect starting?
With the EVAP questions you now have, maybe learning everything you can before possibly dropping the tank (removing the box) to do a pump is smart?
Maybe all the EVAP hosing atop the tank will need to go. You might need time to get the parts together.
Just for giggles, check the battery voltage some morning before you fire it up.
Do you have an electric meter?
My later Ranger(an '05) charges high for ~15 minutes after startup then drops to the usual 14.X charging voltage.
I don't know if your '97 has the "higher charging rate for the first 15 minutes" feature or not.
We all know the older vehicles aren't as finicky when faced with lower voltages, but it's still good to know the condition of your battery and charging system.
EX:
My Ranger started just fine when I purchased it from a neighbor. The battery was >6 years old.
The morning voltage was 10.2 volts. I had to wait a week for Group 59 batteries to be delivered to the store.
Overall, a good experience.
A fellow here urged Ranger owners to swap the coolant hoses at the heater core to slow pitting from within.
You might want to do a transmission pan-drop and filter change....just to know.
My fluid was 15 year old factory fill with only 48k on it. Still, it was dark. Yours might be much worse.
Ford has back-specked to Mercon V, even i f your dipstick says, "MERCON".
I bought a Dorman pan WITH a drain plug for future drain & fills.
That's not to say the store hasn't seen a lot of me, though!
Looks like it was pretty well kept (i.e. no rust, no paint chipping, or major mechanical issues). Tires are brand new since I replaced those and the front brakes almost as soon as I bought the truck. Did a coolant flush about 3 weeks ago, so new coolant and thermostat (AND Heater Control Valve since that decided to grenade itself during the flush!) For the EVAP System, I've replaced the purge solenoid (not the sensor yet) and still have the code. Checked vacuum hoses too and replaced the crumbling ones. Reading around, some folks say that a leaky filler neck/bad pump can throw this code too, so I figure that's worth a shot. I should test the sensor first tonight and see if that's the issue.
Battery was replaced in 2020 iirc but it cranks up every time! Holds 14.X volts. The only issue is that when it's dead cold out there, it takes a bit to crank. After getting it warmer though (5ish minutes) it will crank right away. It's usually only in the morning it does this...
I do have a multimeter, so I'll check that battery and get back to the thread tomorrow with results. Good info on the transmission pan. I had it in the back of my mind to do that eventually since the fluid looks okay on the dipstick right now, but better safe than sorry!
Thread Starter
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Member
Joined: Jan 2025
Posts: 46
Likes: 6
From: Stuttgart, AR
Update for those following along!
Checked battery voltage this morning and was 12.01V with key off, charged up to 14.56V when started up and remained constant (so no high charge rate feature as @Georgeandkira suggested could be the case). Waiting on a call back from a shop on getting a smoke test done, but they seem to echo the same sentiment listed here - change the bad o2 sensor and the issue might resolve itself. Cleaned Purge Flow Sensor, will do multimeter testing on it later today when I get to work on some other small things (hopefully that and the filler neck will resolve P1443...?)
Funny enough, the same shop I took it to said there were "no indicated malfunctions" for the evap system on their code reader, which is MUCH more capable than my reader. Who knows, man
Time will tell with all of this. Only waiting on parts for now. If anyone has any other input, don't hesitate to reply!
Checked battery voltage this morning and was 12.01V with key off, charged up to 14.56V when started up and remained constant (so no high charge rate feature as @Georgeandkira suggested could be the case). Waiting on a call back from a shop on getting a smoke test done, but they seem to echo the same sentiment listed here - change the bad o2 sensor and the issue might resolve itself. Cleaned Purge Flow Sensor, will do multimeter testing on it later today when I get to work on some other small things (hopefully that and the filler neck will resolve P1443...?)
Funny enough, the same shop I took it to said there were "no indicated malfunctions" for the evap system on their code reader, which is MUCH more capable than my reader. Who knows, man
Time will tell with all of this. Only waiting on parts for now. If anyone has any other input, don't hesitate to reply!
Last edited by Ritz; Feb 25, 2025 at 01:45 PM. Reason: clarification
Thread Starter
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Member
Joined: Jan 2025
Posts: 46
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From: Stuttgart, AR
Another update for y'all:
Replaced the Bank 2 upstream sensor and those codes (P1151/P0153) disappeared, but the lean codes remained. Pretty sure it's all something fuel related. I will keep testing and checking around the engine bay but I'm at a loss otherwise. Again, any advice is welcome and encouraged, if you've got it to give.
Replaced the Bank 2 upstream sensor and those codes (P1151/P0153) disappeared, but the lean codes remained. Pretty sure it's all something fuel related. I will keep testing and checking around the engine bay but I'm at a loss otherwise. Again, any advice is welcome and encouraged, if you've got it to give.
Thread Starter
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Member
Joined: Jan 2025
Posts: 46
Likes: 6
From: Stuttgart, AR
Another quick update for all y'all viewing at home:
P1443 was the Purge Flow Sensor (also called Thermistor). Got that replaced and cleared, but my lean codes still remain.
I will be doing more thorough testing this week to get to the bottom of it. Could be an upper intake vacuum leak, could be the fuel pump like I suspected all along. Who can say?
Never hurts to measure thrice!
P1443 was the Purge Flow Sensor (also called Thermistor). Got that replaced and cleared, but my lean codes still remain.
I will be doing more thorough testing this week to get to the bottom of it. Could be an upper intake vacuum leak, could be the fuel pump like I suspected all along. Who can say?
Never hurts to measure thrice!
Thread Starter
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Member
Joined: Jan 2025
Posts: 46
Likes: 6
From: Stuttgart, AR
Another update for y’all
I replaced the fuel pump and filler neck, along with the filter while I was at it. It was good to replace that and it fixed my fuel pressure issues, but the lean codes still remain…
I think it’s time for me to get the upper intake manifold gaskets replaced. I know folks have said that with the ‘97 OHV there’s a TSB out about the fuel rail gaskets and causing these conditions. I’ll try to get a smoke test first, but I feel like this is the only thing left it could be. Any tips?
I replaced the fuel pump and filler neck, along with the filter while I was at it. It was good to replace that and it fixed my fuel pressure issues, but the lean codes still remain…
I think it’s time for me to get the upper intake manifold gaskets replaced. I know folks have said that with the ‘97 OHV there’s a TSB out about the fuel rail gaskets and causing these conditions. I’ll try to get a smoke test first, but I feel like this is the only thing left it could be. Any tips?
Thread Starter
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Member
Joined: Jan 2025
Posts: 46
Likes: 6
From: Stuttgart, AR
FIXED
Hey y'all, sorry to revive this dead thread, but it won't be alive for much longer!
The issue was fixed with the intake manifold gasket job. Upper, Lower, Valve Covers, and Fuel Rail. Should've got some pictures of that last one, it was in pretty rough shape!
No codes for ~500 miles now. Thanks for the help, y'all! If you're experiencing the same thing as me for this engine, the gaskets are likely your problem.
The issue was fixed with the intake manifold gasket job. Upper, Lower, Valve Covers, and Fuel Rail. Should've got some pictures of that last one, it was in pretty rough shape!
No codes for ~500 miles now. Thanks for the help, y'all! If you're experiencing the same thing as me for this engine, the gaskets are likely your problem.
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