Ok, I am working on an '01 Lightning that was purchased used.

It was running fine for the past 6 months, it has several mods.
In the last month i'm getting p0171 and p0174 lean bank 1 & bank 2.
I'm loosing my mind, i've had it smoke tested, no leaks from smoke found.

So far we have checked Mass Air flow, fuel pressue, fuel volume.
The weird thing is when we data stream the Long term fuel trim is pegged at 25% correction at idle.
The Mass airflow checks good, 02's are switching good, temp sensor good.

Once i crack the throttle and bring it up (900rpm or so) The fuel trims normalize.

I can drive it all day long and keep the light from coming on if i don't let it come to a complete idle.

It seems to miss slightly when warm at an idle as well.

Could it possibly be a vacuuk leak that only opens when the engine is HOT?

We saw a wiff (small amount) of smoke come out from under the intake area for a second when testing it but could not duplicate it.
I am thinking it's because the engine wasn't as hot as it should have been?

Someone please help me, i am running out of ideas here.

Thanks in advance!

-Richard

 

CHeck the air tube that runs to the backside / bottom of the lower intake - there's a rubber elbow on it that deteriorates over time and cracks - letting in unmetered air. It's a real pain to get to - most people have to take the S/C off.

Bird

 

+1 Part No. YL3Z 6C324 BA includes the hose and a new PCV. You might as well do the intercooler cleaning at the same time cause like Bird says, getting the hose off and back on the back of the lower intake is almost impossible without removing the SC.

 

I agree, sounds like this also.

 

I had to use my 1/2 breaker bar on some of those suckers!!

Thanks guys you saved me!

-Richard

 

Start with the 4 middle bolts, then front 2 and finally the 2 in the back of the s/c. Torque them to 18 inch lbs followed by 33ft lbs.

 

And don't forget to put anti-seize on the threads before you put them back in - won't have to use the breaker bar next time.


Bird

 

wouldn't of found it without the knowledge here.

Thanks all!

-Richard

 

good to see us getting back to basics.......helping people with problems. Awesome