Chad2003

my check engine light came on I checked the code The code said engine too lean so I replaced my intake gasket thinking that would fix the problem so I cleared the code and was good for a few days then the code came back on and I can't clear it now. What could be the problem?

link5631

We could offer more help if we had a little more information. Is the system lean on both banks, bank 1 or bank 2? This is vital to being able to diagnose it over the internet or even begin to tell you what could possibly be wrong. Check your code again and post up the code for us to see.

Chad2003

The code came up bank 1

Jbrew

Do you know which engine you have..or is that too personal?

Chad2003

4.6L

link5631

So bank 1 on your 4.6l, if memory serves me right, would be the passenger side of the vehicle. Bank 1 is whatever side your number 1 spark plug is on and with the Triton's number 1 spark plug is going to be on the passenger side.

Knowing that it is only lean on bank 1, we can pretty much start eliminating potential issues, the MAF sensor being one of them, since it would make both bank 1 & 2 lean. Try using some propane or MAP gas to go along the passenger side of the engine while it is running. Try to go over anything that could potentially cause a vacuum leak and listen carefully to the engine to see if it goes up in idle. If it revs up, you found your culprit. Also, try taking a look at the PCV elbow on the back side of the motor. Just find your PCV valve on the passenger side and follow that hose to where it connects to the back and check it for cracks. If you can't find a vacuum leak like that, you may want to try renting or making your own smoke machine to smoke it out, just to be double sure.

If you possess the patience, time and tools to remove the 02 sensors on the passenger side, I would remove them and test them with a multimeter. All sorts of youtube videos to show you how to test them. 02 sensors can cause lean/rich codes on one bank when they go bad and won't always throw a 02 sensor code.

If you fail to find a vacuum leak and your 02's are fine... then, it's reasonable to assume that the lean code is not caused by air entering the engine, rather it being starved for fuel. If that were the case, lazy injectors would be the likely culprit.

EDIT: Mileage would also be fantastic to know. You can never give too much information about your vehicle when you're getting help to diagnose it over the interwebs. Don't be afraid to give us every detail about the truck, it all helps in its own way. Also, any other codes?

mbb

Read fuel trim at idle
That when vacuum is most, so air leak off chart relative to small needed amt

If its problem at idle its probably air leak

If its problem at high speed, its possibly fuel restriction

No misfires?
Unburnt fuel fools the 02 analyzer

Pcv tube leak
large leak after MAF, before throttle
Bad MAF