4.0 SHOC Lean Codes

[WDouglas]

I am getting lean codes after installing an AFE cold air intake. Fuel trims at idle are up to about 20%. Claer the code, reset the pcm, evry thing is ok for about 4 trips. The short term fuel trims will then be around 0, but long term is up to around 20%. Any ideas?

 

[adsm08]

Yeah, your POS "crap air intake" is messing with the MAF readings. It's a common thing with those after market kits. Throw it in the trash and put the stock system back on, your issue will go away.

 

[Earl43P]

The Master of the Obvious, Mr. Tactful ^ and I welcome you to The Ranger Station!

I might add that 4.0's are notorious for leaking upper and lower intake manifold gaskets. A leak in the intake tube from the TB to MAF will cause it to run lean. The PCV tubing can also introduce a vacuum leak and has been the cause in the past.

Read through this: http://www.therangerstation.com/Magazine/Summer2003/VacuumLeaks.shtml

 

[4.0blue98]

Before you throw the intake away, have you cleaned the MAF lately. I have an AEM bruteforce and really like it but don't have the prefilter. If you run it in the rain or in my case the saltspray this time of year it'll foul the MAF and throw the two lean codes. Hit the MAF with some MAF cleaner and it may be okay for a while. I'd recommend a prefilter wrap if you don't have one.

Just my 2cents.

 

[Redneck_Ranger]

Yeah, your POS "crap air intake" is messing with the MAF readings. It's a common thing with those after market kits. Throw it in the trash and put the stock system back on, your issue will go away.

I have the brute force as well and have no problems....

Take it apart and redo it, with some silicone around the fittings on the intake tube. Clean your MAF sensor as well. Is the code you're getting just a generic lean? Because you may have a vacuum leak if it's not the sensor/intake.