Hey guys,

1.5 year have passed now since I have got my D2 (2003) and I still have these codes that keep coming back around 25-28 MPH (codes only come at these speeds). (Still don't have the truck plated and on the road as it doesn't pass emission)

I have done the following since buying the truck that could have help the running of the engine:

-Timing chains timing gears
-Water pump
-Water temp sensor
-180 grey stat
-rear o2 sensors
-new o"rings on injectors
-new pcv valve and hoses
-new brake servo connector on upper intake
-new intake and throttle body gasket
-new spark plugs and wires
-Oh yeah big ticket item ENTIRELY NEW ECU HARNESS $$$$
-I have had the ECU's fully updated with the latest firmware using auto logic and had it do an adaptive reset.

I have swapped out the MAF out of my parts truck to see if it might help, even though I knew these fail lean usually.

Not much else to do but replace all the O2 sensors, front look like the data is good, rear have very little change in voltage but are functioning and have no 02 codes.


Now heres my latest theory, is it possible my AICV is letting too much air through or stuck open and making my truck run rich? It recently starting giving a humming noise. I have a spare from my parts truck i am thinking of trying, if I do is there anything special I need to do i.e adaptive reset?

Thanks for the help.

 

For those two codes, the most common cause that I have found is a malfunctioning MAF sensor. I have seen either the sensor itself cause it or a fault in the wiring. Even though it's not 100% conclusive, try watching the live data during a few wide open throttle snaps and make sure you're getting a good strong spike at the beginning of the throttle snap. I think mine usually jumps up to between 5 and 10 Hgi.

 

Took out the y pipe tonight and noticed that I had an exhaust leak at the flange that connects the maifold to the down pipe on both sides. I am replacing the gaskets and a few studs along with the front O2 sensors.

I suspect this will cure my problems.

 

That can definitely cause some weird o2 sensor readings. Hopefully that will do it!
Good luck!

 

Good evening gentlemen.

After replacing the two gaskets and two front O2 sensors I am still running rich. I just don't get it... My wallet is starting to get lite these days. Any help would be appreciated. I doan't even know where to look anymore.

 

Make sure you have the correct part # MAF. I had a guy that was at 4 shops and no one could fix his rich codes. He had the smaller pipes and maf from a 4.0 on his 4.6.

 

Yeah I have the big pipes for the 4.6... I however did try the maf from my 4.0. I simply removed the safety screws and switched out the sensor as appose to the whole assembly. This being said the part number on the actual sensor was the same. Could someone undo the safety screws on their sensor on their 4.6 and confirm the part number?

 

Does anyone know if it's possible that I have the wrong injectors in my truck? I don't have the typical green ones installed in fact they are black and they don't have a slit for the clip that holds them to the fuel rail.

I am wondering is someone changed out the injectors at some point with ones with a higher flow rating and the ecu cant seem to pulse them fast enough to cut back the volume of fuel going into the engine. This is one of my running rich therories.

I have a set kicking around from my 2000 4.0 parts truck, will these work in my 4.6? If so i am going for order another eBay o ring and filter kits and through them in.

 

One thing you could try is cleaning your throttle plate. I have seen this happen on a few vehicles where the throttle plate gets so dirty that the carbon buildup stops the plate from closing all the way. What happens then is, the throttle position sensor tells the computer that the throttle is open and adds fuel to make up for air that is not actually coming in.

 

Good news everyone, my vehicle is finally working properly and no longer running rich. As soon as I changed the injectors the truck leaned out to a normal adaptation and all emissions systems went into ready mode. Thank you to everyone who's given their two cents of advise to help me along.