2001 Lincoln LS V8. Engine missfire and p0174 Code. Please Help!!!

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ecarlincoln

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Hello im new to this forum and to lincoln, I recently purchased my first and i love it!

2001 Lincoln LS, V8. Developed a misfire and is throwing code P0174 System too lean bank 2. It doesn't seem to be any single cylinder missing and I've ruled out a bad coil. Lean usually means vacuum leak but I haven't been able to find one... Any thoughts?
 
Please do tell, how did you "ruled out a bad coil?"
 
ecarlincoln said:
Picked up a new coil and swapped it to each cylinder restarting every time, no change
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Now, go get seven more (all OEM), and eight new spark plugs. Make sure the plug gaps are set to 1.0mm. Replace all at once.
Once you have done that, you can move on to other troubleshooting. (Also, check all the connectors at the fuel injectors.)

The problem with your procedure is that it doesn't allow for there to be several marginal coils at the same time. Most people don't notice the slight misfires until more than one coil is bad.
 
joegr said:
Now, go get seven more (all OEM), and eight new spark plugs. Make sure the plug gaps are set to 1.0mm. Replace all at once.
Once you have done that, you can move on to other troubleshooting. (Also, check all the connectors at the fuel injectors.)

The problem with your procedure is that it doesn't allow for there to be several marginal coils at the same time. Most people don't notice the slight misfires until more than one coil is bad.
Click to expand...

Is it common to get a lean code with a bad coil? I would think one or more bad coils not firing would cause an extremely rich exhaust gas? Its time for coils regardless so I'll pick some up in the morning and give it s shot, I did check the injectors there all plugged in and firing
 
ecarlincoln said:
.... I would think one or more bad coils not firing would cause an extremely rich exhaust gas?...
Click to expand...

Doesn't work that way. The O2 sensors indicate the amount of oxygen in the exhaust, not fuel. Too much oxygen = lean mixture. Too little oxygen = rich mixture. If there is a miss (no ignition) then the exhaust has lots of oxygen and lots of fuel. The PCM can't see the fuel, but it does see the oxygen. From this, it decides that it must be lean.

You may still have a problem after replacing the coils and plugs, but it will be easier to troubleshoot once you have eliminated them as any part of the issue.
 
joegr said:
Doesn't work that way. The O2 sensors indicate the amount of oxygen in the exhaust, not fuel. Too much oxygen = lean mixture. Too little oxygen = rich mixture. If there is a miss (no ignition) then the exhaust has lots of oxygen and lots of fuel. The PCM can't see the fuel, but it does see the oxygen. From this, it decides that it must be lean.

You may still have a problem after replacing the coils and plugs, but it will be easier to troubleshoot once you have eliminated them as any part of the issue.
Click to expand...

Changed the remaining 7 coils, All 8 plugs and gapped them. no difference
 
Use a mechanic's stethoscope to listen to each fuel injector. If any aren't clicking or otherwise sound different, you may have found the problem. Search for air/vacuum leaks. There are several ways to do that.
Disconnect the MAF. Do things get better?
What exact codes are you getting?
 
joegr said:
Use a mechanic's stethoscope to listen to each fuel injector. If any aren't clicking or otherwise sound different, you may have found the problem. Search for air/vacuum leaks. There are several ways to do that.
Disconnect the MAF. Do things get better?
What exact codes are you getting?
Click to expand...


P0174 is the only code, I did listin to the injectors with a mechanics stethescope they all seem to fire the same, tried disconnected the maf made no diffrence. I also pulled the air intake off in my search for a vacuum leak and didn't find any. Intskr gaskets or clogged injector maybe?
 
You got a vacuum leak somewhere. Look for old split connectors. I have an 01V6. Replaced lots of connectors and hoses, boots, etc. Listen for hissing sound when pulling on hoses. There are clever ways to find vacuum leaks.
 
A little update, Checked all the injectors, Checked fuel pressure (30 psi 40 psi with vacuum removed from regulator) So the regulators good, replaced all coils, Both sides and all cylinders are miss firing. Ive checked every vacuum line for leaks with carb spray including the intake manifold and the cars still running horribly.. Now The only 2 codes im getting are lean bank 1 and lean bank 2.... Originally it was just lean bank 1 but now its saying bank 2 as well
 
Im starting to think maybe its a bad PCM? Any ways to check that? and are all 01 V8's interchangeable?
 
ecarlincoln said:
A little update, Checked all the injectors, Checked fuel pressure (30 psi 40 psi with vacuum removed from regulator) So the regulators good,...
Click to expand...

That's not a regulator. The LS is a returnless system. Fuel pressure is regulated by the PCM sending commands to the REM to control the power applied to the fuel pump (using PWM). The thing at the end of the fuel rail with a vacuum connection is a fuel pressure sensor. The spec (for gen II, anyway) is 30 to 55 PSI, and it's usually closer to 55 than 30. Still, it does look like fuel pressure is probably not this issue...
Valve timing?
 
valve timing as in a bad sensor making the ecu changing timing or as in timing chain jumped? is that even possible with these motors without them blowing up?
 
ecarlincoln said:
... as in timing chain jumped? is that even possible with these motors without them blowing up?
Click to expand...

Yes, if only the exhaust jumps by only one tooth. However, I would expect that it would be running pretty rough. Maybe it hasn't jumped yet, but a tensioner has failed and that is causing the timing to be slightly off. It's just a thought, and I don't really stand behind it. Have you checked the MAF?
 
joegr said:
Yes, if only the exhaust jumps by only one tooth. However, I would expect that it would be running pretty rough. Maybe it hasn't jumped yet, but a tensioner has failed and that is causing the timing to be slightly off. It's just a thought, and I don't really stand behind it. Have you checked the MAF?
Click to expand...


Yeah I did u plug that MAF no change, Im stumped! How hard is it to remove the timing cover and check?
 
Have you checked for an intake manifold leaking air in and leaning the system. I did mine about a year ago and only last month on a different vehicle. This cold weather can bring stuff to light. I meant to say the Gasket.
 
jwct7 said:
Have you checked for an intake manifold leaking air in and leaning the system. I did mine about a year ago and only last month on a different vehicle. This cold weather can bring stuff to light. I meant to say the Gasket.
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I sprayed tons of starting fluid around the intake didn't seem so make a diffrence
 
Would you happen to have the workbook procedures to get to the timing chain? How do you determine from that point the chain jumped or bad tensioner?
 
I took the car to a local shop, he said he didnt think it was a timing issue. Ran a smoke test and ended up replacing an O ring and 2 seals on the throttle body but its still running like crap!
 
ecarlincoln said:
I took the car to a local shop, he said he didnt think it was a timing issue. Ran a smoke test and ended up replacing an O ring and 2 seals on the throttle body but its still running like crap!
Click to expand...

Did he do a compression and leak-down test? Or, did you or he pull the valve covers and verify that all the flats lined up?

Do you still have low boost on the brakes? I assume the smoke test didn't show any leaks other than the issues you indicated were addressed on the throttle body.
 
joegr said:
Did he do a compression and leak-down test? Or, did you or he pull the valve covers and verify that all the flats lined up?

Do you still have low boost on the brakes? I assume the smoke test didn't show any leaks other than the issues you indicated were addressed on the throttle body.
Click to expand...


Brakes seem to be fine now. The smoke test also found a broken O-Ring that he has replaced. Did a compression test and everything was in spec. Not sure about a leak down but i would assume so. Cars still throwing bank 2 lean code.

Next step is going to be verifying timing, its just odd because for how bad it runs at idle and low accel, after 2500 rpm's it runs excellent
 
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