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Discussion Starter #1
I have posted plenty too. I get a P0171 after I disconnect the bat. It eventually turns into a P1131. Last week, I saw that a plug wire (msd) was too close to the passenger side front injector harness and corrected the burn through. I have cleaned and swapped maf's, listened to my injectors (all sound same), checked resitance at the injectors, driven with vacuum plugs on the manifold, and I still get mild surging (periodically) and a rough idle. I will swap injectors from side to side this weekend in hopes that my P1131 turns into a p1151. But in the meantime, could it really be that I have clogged or hung-up injectors that sound and measure up normal? Could the ign wire have permanently caused one to run amok? All my plugs on the passenger side get dark and sooty because the computer is trying to correct my lean condition, but shouldn't one plug look lean? My smog is now three weeks late, but I can't pass in this condition. Could there be an exhaust leak that I cannot hear? I am too old for these kinds of problems, you know! help?
 

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if you're getting lean/rich codes on only one side, it may be indicative of a faulty O2 sensor.....if possible swap the upstream O2 sensors and note which side the code comes back.....it the code switches sides after the O2 swap, then that is your answer.....but if it stays on the same side, and only on that side, you may have an exhaust leak near the O2, or a leak in the intake manifold gaskets

i have a pair of 50k mile Bosch O2s that i removed while they were still working (to replace them with OEM motorcraft units), incase you're interested in them
 

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Discussion Starter #3
Upsteam 02's are a week old.

They also read the same thing my original 166k 02's read. When I pulled the passenger side plugs, they were all sooty, even though the P1131 and today's
P0151 mean they are reading lean (but adjusting richer) that side. I am also going to tighten the intake manifold to the highest values. What about those hoses to the egr sensor by the firewall, where do they come from? Would it be the passenger side exhaust manifold by any chance?
 

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Discussion Starter #5
1997 4.6 bird is better but still wrong.

What I have done so far is: yesterday I swapped the injectors from side to side, as well as the coils. I also tightened down the passenger side of the intake manifold a little more. It was originally all torqued to 22 ft lbs. Now the intermittent rough idle happens farther apart, and is less rough. I still get a pending code P1131. The light surging I periodically got at light throttle I no longer get. I had thought that my P1131 would turn into a P1151, but it appears the injectors are all good. That leaves me with a possible intake or exhaust leak to dig up. The new Ford brand pi manifold was a little rough machined as far as I was concerned, but I didn't expect it to not seal. Since tightening might be why it's running better. Just what is the most anyone has ever tightened to? I think max was supposed to be 25 ft lbs, but who's gone more and why?
 

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http://www.aa1car.com/library/ford_lean_codes.htm

From the section entitled WHAT A LEAN CODE MEANS:

"A lean fuel condition may exist if the engine is sucking in too much air and/or the fuel system is not delivering enough fuel. If bad enough, a lean fuel condition may cause lean misfire, a rough idle, hesitation or stumble when accelerating, and/or poor engine performance.

Unmetered air can enter the engine through a vacuum leak, a dirty airflow sensor that is not reading airflow accurately, an EGR valve is not closing and is leaking exhaust into the intake manifold, an EGR valve that is allowing too much flow (because the EGR differential pressure sensor that monitors EGR flow is faulty and is under-reporting EGR flow)."


In the thread I referred to, in the section I referred to (Induction System), one of the items listed is air leaks after the MAF sensor. An air leak after the MAF constitutes unmetered air. Thus, the service manual, at one point (as I stated in my previous post), can be construed as defining P0171 as unmetered air entering the system after the MAF sensor.

From the 1994 PCED manual:

The Mass Air Flow (MAF) Sensor is attached internally or externally to the air cleaner assembly and measures the quantity of air delivered to the engine combustion chamber.


Air entering AFTER that point is unmetered, or unmeasured. This includes a vacuum leak, and even an EGR valve that is stuck open, or has a leak in the diaphragm.
 
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