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Lean on both banks - brand new fuel filter blocked?

D

delkra

CEG'er
Joined
Aug 11, 2009
Messages
77
Location
Delaware
I recently replaced the Bank 2 O2 sensor (upstream) on my 99 SE after I got a code about the that sensor and P0420 together. I also noticed that my car needed a fuel filter because the one on there seemed to be original to the car (!!) :crazy:. I had to cut through the pipe clamp with dykes because it was so rusted it wouldn't move. Knowing the person who owned it before me, I doubt she knows the car has a fuel filter. :crazy:

So anyway, the code for the O2 sensor cleared up and infamous P0420 is gone as well. But - as I was driving today, I noticed the CEL come on again. :blackeye: Crap.

Now I'm getting the P0174 and P0171 with a "notation" on my scanner that says "Pd". From what I can tell, this means lean on both banks. No clue what Pd is... :mad: From searching the forums I'm thinking big vacuum leak. But I haven't done anything to the intake system since I got the car. The only thing I've done is clean the MAF sensor with an MAF sensor cleaner - and that was months ago.

Is it possible that the brand new (Fram) filter I put in there is blocked somehow? That's the only thing I can think of from the work I've done recently that would cause a lean condition over both banks... :help: Any ideas??? :confused:

Thanks
-Delkra
 
I forgot to mention - the O2 sensor I replaced is bank 2 - the easy one. I replaced bank 1 (under the coil pack) during the summer.

Any help is greatly appreciated!
 
bank 1 is the easy one. Bank 2 is the one under the coil pack.

"pd" means the code is pending.

You will need to measure the fuel pressure at the rail to see if the fuel flow is restricted. Are you sure you didn't install the filter backwards?

The lean codes are usually due to vacuum leak problems although a restricted fuel flow can also cause them.
 
projectSHO89 said:
bank 1 is the easy one. Bank 2 is the one under the coil pack.

"pd" means the code is pending.

You will need to measure the fuel pressure at the rail to see if the fuel flow is restricted. Are you sure you didn't install the filter backwards?

The lean codes are usually due to vacuum leak problems although a restricted fuel flow can also cause them.
Click to expand...

You got that backward. Bank 1 is the rear bank, or as you say, under the coil pack.

If in doubt about the fuel flow to injectors a fuel pressure gauge is the best way to tell. If you think the new filter may be plugged, pull it off and try blowing through it. It is very evident.
 
Hmm... I would've guessed vacuum leak as well - except that nothing I've done recently had anything to do with vacuum (O2 sensor, fuel filter, etc.).

I going to check filter direction, but I doubt that is the problem. If it is, I'll feel like an idiot, though.:eek:

Anyone know the appropriate fuel pressure ranges I should be looking at? I assume I need the key on, engine off and key on, engine on numbers... I haven't been able to find a solid answer so far...:confused:

Thanks!
 
Somewhere around 45-60 psi for a 99 2.5 Contour. That's with the fuel pump forced on with the scan tool.

There's a complete diagnostic procedure in the PCED.
 
possible vacuum leak

possible vacuum leak

I had the same codes in a cougar. Turned out to be a small vacuum leak on the bottom side of the intake tract between the filter box and throttle plate. You can do two things to find leak, spray carb cleaner around the intake tract, idle speed will increase when you find the leak. You can use a small piece of fuel line stuck in your ear as a stethoscope. You will definetely hear when you get close to the vacuum leak. If necessary remove inlet tract so you can inspect very closely.
 
If this were a vacuum leak, though, wouldn't the codes get thrown right after it enters closed loop? :shrug: From what I understand the codes get thrown after the second ignition cycle of lean operation.

It seems to be really intermittent. I checked the fuel pressure at idle, seems fine (I forget the exact numbers, but they matched the manual specs). I've gotten it once after 20 miles - and again like 2 tanks of gas later.

I am going to try the carb cleaner trick, though... just in case.

And I'm replacing the fram chinese junk filter with a motorcraft one, just for good measure. :cool:
 
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