ok so my check engine light cam on AGAIN and its trowing the same codes as last time. its was just under a year ago and i had just got the truck so i took it to the dealer ship and was told they replaced all the o2 sensors (but whats the chance of that) now they are saying its the intake manifold what i want to know is would those codes come up if the intake manifold was bad? im not going to take it back to them because i can fix it myself and if anyone can help it would be a great help!

 

what year truck?

 

sorry its a 99 xlt 4.0 ohv witch brings me to another point witch ill address later.

 

im gonna say yea its your intake gaskets...common problem on the OHV 4.0

 

wow well ok thanks man! so would you say it would be best to replace the manifold and gasket as well as the o2 or what ? how would you do it?

 

i wouldnt worry about the manifold unless its cracked...pull it off and inspect it...but its prolly just the gaskets

 

OK thanks man! is there anything i can do to help performance while i have the manifold off? is there anything i can do to help the motor breath easer?

 

o and i know this is off topic but i plan on doing a tune up and have heard running seafoam threw the motor and fuel system will help clean out all the build up and clean out the system? have you tried using seafoam how well did it work and where can i get some if you recmond using it?

 

I had the same thing going on, I replaced all O2 sensors, mass air flow sensor, fuel filter, and after all that time and money, I found out that one of my rubber air flow lines that runs along the left side of the manifold had a tear in it. Once I repaired/replaced it, check engine light......never came on. Im not sure if that is what it is, but we all encounter problems, and it could be something as simple as what I delt with. Good Luck man.

 

When you get both codes it usually is a vacuum leak, allowing unmetered air into the engine.

Any vacuum hose or gasket can cause the issue, can be a real PITA to track down.

I can tell you this on my 99 the valve covers were leaking, so I replaced all upper gaskets. Now my truck idles smoother.

 

Wow thanks for all the info everyone I can use a can of carb cleaner to find a vacuum leak I have to fix it next weekend when i get my check so ill let you all know how it goes and again thanks for all the info!!

 

I'm not completly familiar with the OHV engine, but this is the rubber elbow that is known for problems. Passenger side of the engine.

 

OHV doesn't have it.