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Solved P0174 too lean?

Tunrau

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I have been hunting down a lean code P0174 only not showing a P0171 code, so my understanding is this is driver side only intake leak?

Truck starts and idles rough in cold weather when engine cold.

So far I have, cleaned MAF sensor, replaced IAC sensor, replaced Spark Plugs/Wires, Air Filter, checked all hoses and they all seem to be in good condition and tight.

I am down to the dreaded Intake Gasket job or are there any other possibilities to check before I rip things apart?
 


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koda2000

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Most likely intake gaskets/O-rings. Very common issue on the Job 1 SHOC 4.0L engines. Ford went with much thicker O-rings and a 1-piece intake on the Job 2 engine. They're less likely to leak. The Job 2 intake is only held on w/4 bolts too.
 




BrooklynBay

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Tunrau

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I sprayed carb cleaner on all hoses and valleys between intake gaskets though it was hard to get in there, no noticeable difference in idle. Gave it a shot with blocking air intake and blowing smoke in but didn't see any coming out. Not sure where to go from here other than just do the swap on upper and lower gaskets, I am planning on doing it tomorrow unless there are any other things I could try?
 




koda2000

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Just go ahead and replace the upper/lower intake manifold gaskets/O-rings. You'll see how brittle and dried up your old ones are. Super common issue with the Job 1 SOHC engine.

I've never had any luck with spraying stuff around the intake to try to find a leak.
 




Tunrau

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Swapped the gaskets outout thats definitly fixed the issue, it starts and runs great now.

Now ive created a new issue, i think i rested my arm on the TPS sensor too hard, now im getting code p0123, throttle position sensor high input.

Im thinking about ordering a new sensor and swapping out but not sure yet. I also noticed the thottle plate was sticking, you can feel it when you press the gas, it sticks a bit at zero throttle position. May have to take that apart again and clean it.
 




koda2000

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Swapped the gaskets outout thats definitly fixed the issue, it starts and runs great now.

Now ive created a new issue, i think i rested my arm on the TPS sensor too hard, now im getting code p0123, throttle position sensor high input.

Im thinking about ordering a new sensor and swapping out but not sure yet. I also noticed the thottle plate was sticking, you can feel it when you press the gas, it sticks a bit at zero throttle position. May have to take that apart again and clean it.

The throttle body plate can stick if the TB has carbon build-up behind it, or if the plate does't have enough clearance/opening when at idle. There's a screw/small bolt that can be used to adjust the throttle plate if necessary, turn it too far and you'll end up raising your idle (sometimes this is a good thing) and turned out too far and the plate will stick. I periodically remove my throttle body to clean the carbon out of it. Perhaps you bent something from leaning on the TB... ? Might explain why your TPS is out of range too.
 




Tunrau

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The throttle body plate can stick if the TB has carbon build-up behind it, or if the plate does't have enough clearance/opening when at idle. There's a screw/small bolt that can be used to adjust the throttle plate if necessary, turn it too far and you'll end up raising your idle (sometimes this is a good thing) and turned out too far and the plate will stick. I periodically remove my throttle body to clean the carbon out of it. Perhaps you bent something from leaning on the TB... ? Might explain why your TPS is out of range too.

Im going to pull it out tomorrow and clean it up, i did notice it was sticking pretty good when shut. Im hoping this fixes the check engine light since it has no other problems.

I wouldnt mind turning the idle up actually, it idles at 600rpm which is about 100 lower than i like it.
 




koda2000

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Im going to pull it out tomorrow and clean it up, i did notice it was sticking pretty good when shut. Im hoping this fixes the check engine light since it has no other problems.

I wouldnt mind turning the idle up actually, it idles at 600rpm which is about 100 lower than i like it.

I agree with you on the idle RPM, but that's about where the SOHC's idle. I turned mine up to 600-650 'ish because I didn't like it that low either. You might see a sticker, or writing, on the TB that says "DO NOT CLEAN" but if it's all full of carbon I figure that's dumb and it needs to be cleaned. I use MAF or parts cleaner and an old tooth brush, being careful to not let any run into the TPS. You can do it w/out removing the TB, but you can do a better job with it off. The gasket is reusable. While your at it remove the IAC and clean that too.
 




Tunrau

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I agree with you on the idle RPM, but that's about where the SOHC's idle. I turned mine up to 600-650 'ish because I didn't like it that low either. You might see a sticker, or writing, on the TB that says "DO NOT CLEAN" but if it's all full of carbon I figure that's dumb and it needs to be cleaned. I use MAF or parts cleaner and an old tooth brush, being careful to not let any run into the TPS. You can do it w/out removing the TB, but you can do a better job with it off. The gasket is reusable. While your at it remove the IAC and clean that too.

Actually the IAC luckily is brand new but I think I know where I messed up, when I cleaned the whole upper manifold I dunked it in a tub of hot water and soap overnight, but I left the throttle body and sensor on it lol

Think I should just order a sensor, strangely even with the sensor tripping the warning light I dont see any issues with the throttle.
 




koda2000

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Actually the IAC luckily is brand new but I think I know where I messed up, when I cleaned the whole upper manifold I dunked it in a tub of hot water and soap overnight, but I left the throttle body and sensor on it lol

Think I should just order a sensor, strangely even with the sensor tripping the warning light I dont see any issues with the throttle.

Like all automotive sensors, they are designed to work w/in a specified range. The PCM uses these values to determine what the sensor is seeing and to respond/adjust things appropriately. When the PCM sees that a sensor is reporting outside of it's expected range it sets an ODB II TDC. The effect on how the vehicle performs may, or may not, be significant. Getting liquids inside an electronic sensor is never a good thing. If you can't dry it out, replace it.
 




Tunrau

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Worked like a charm! Dried the sensor out, cleaned up the throttle body it runs like new.

Thanks for all the help :)
 




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koda2000

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Worked like a charm! Dried the sensor out, cleaned up the throttle body it runs like new.

Thanks for all the help :)

Cool! Glad to help.
 








BrooklynBay

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