5.4 running lean....

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Aug 5, 2008 | 01:48 AM

Jason01

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5.4 running lean....

For any of you who remember me, I have had many problems with my ford, mostly expected for the 229K miles, but I have one that I cant make go away.

The check engine light is coming on, and the code that I keep getting is bank 1 lean. The LTFT for both banks was at 22.6, which would make me think that the problem is universal(both banks). The idle is a lil rough in gear when warm, but smooths right out as soon as you touch the accelerator. The truck seems to have more power at half to 3/4 throttle than full throttle, and I cant find a vacuum leak anywhere(I have plugged every port on the intake to check, no difference). The truck pulls extremely hard at half to 3/4(you gotta manually hold the lower gears), been like this for about 10K miles....
New fuel filter, MAF, TPS, Timing chains, all O2 sensors, DPFE sensor, air filter, cleaned TB.....
what next? please help!

Aug 5, 2008 | 10:52 AM

LxMan1

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From: Louisville,Ky.

Have you checked to see the actual fuel pressure?

Replaced the PCV valve hose elbows?

Aug 5, 2008 | 01:17 PM

Jason01

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well, i feel retarded... never did think to check the actual fuel pressure!
I should be able to get a hold of a gauge tomorrow morning, provided i wake up early enough. Are the regulators a common thing to fail on the trucks? Now that I think about it, being its been like this for 10K miles, i cant imagine if there is a problem that its the pump, wouldn't that have failed by now?

Aug 5, 2008 | 04:25 PM

BareBones

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From: Burnsville, MN

Given your symptoms, there's no good rationalization for not testing the fuel pressure...

Aug 7, 2008 | 12:57 PM

Jason01

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Well, I got a hold of a new pressure gauge today. I had 32lbs on idle, and 43 with the vacuum line on the regulator disconnected.... O, another thing, the truck idles beautifully when its cold(first 5 min of runtime), and after that is when the idle will start to get a lil rough. The only vacuum line I haven't plugged yet is to the brake booster, so unless I have a bad gasket somewhere, I cant imagine its a vacuum leak. My next guess is the CTS or AIT sensors. The CTS was regestering 197 on the freeze frame data(and the truck was full operating temp), so I would be leaning twords the AIT sensor... Anybody have the resistance chart for that particular sensor?

ANY help is greatly appreciated!

Aug 7, 2008 | 09:59 PM

projectSHO89

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From: St Louis

Still bet it's a vacuum leak.

Check the PCV hose elbow.

There's probably nothing wrong with the sensors you mentioned.

Steve

Aug 8, 2008 | 12:53 AM

Jason01

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Well, I Know it cant be the PCV system, as the ports are blocked off, and a breather is in the valve cover(temporarily). I have plugged every single vacuum line on the engine, except the brake booster, and drove it. It always has the same symptoms. The idle in gear when warm is rough, but the slightest throttle clears it up, and the pcm records no misfires....

BTW, it is now running good at full throttle, the only irritating thing left(more of less) is the rough idle. I cant find a vacuum leak for the life of me, but it acts like there is one.....