I failed my smog test.... ANY IDEAS?

 

Sure, study harder next time.

In all reality though, it's a bit hard to tell you what wrong simply by reading numbers on a page with no other symptoms listed.

How long since the last tune-up?
There's over 200K on the odometer, has the engine ever been rebuilt?
A valve job ever done?
Is the catalytic converter original?
Are the O2 sensors original?
Any trouble codes in the computer?
Etc, etc, etc...

 

I do have that issue where things get all wonky when I am near 1/4-1/2 tank.... the multiple misfires, and stalling on the freeway bit --- other than that, no codes or issues

I am getting around 14 mpg combined

I did plugs, wires, cap, rotor about 3500 miles ago

I don't think the motor has been rebuilt, but my father in law said that it had when it was new for a check engine light back in 96.... but he was very vague and that is all he told me as this used to be his van

it has been around 3500 miles since my last oil change, I use 10-30 mobil 1 full synthetic and an oversized ford fl1a fliter (same size as a fram ph8a)

 

That's the fuel pump failing. A weak FP can also explain you failing the smog test since the correct fuel pressure is not present at the injectors.

 

i am not sure it is the fuel pump failing.... why has it not failed?

this vehicle has done this the entire time I have owned it. if I fill it up with gas, all the problems are gone, like they were never there. I know when it happens, I have like 10 gallons left in the tank, so I really don't see how the pump isn't being cooled at that point, that is 1/3 of the tank

something leads me to believe this is more of an electrical issue

it is something to look at though, and at this point, trying to get ideas.....

the vehicle still runs, and i'm getting 14mpg on it.....


a friend recommended cleaning my egr out, said he had similar readings on his dodge truck, and that cleaning the egr and something about a plastic disc that fell somewhere fixed it

 

The fuel acts as a heat sink for the pump. When the fuel level falls below the pump motor, the motor runs hotter and doesn't pump as well. This is a well documented symptom and solution, search around.

 

yup, i know that part. when I did my smog test, I had a full tank of gas minus a gallon or 2

 

Have you check the fuel pressure to see what it is? The pump may be weak enough that, though it runs better when above the 1/3 tank, it is not making full pressure the rest of the time.

The 94-03 Magnum series engines do not have EGR systems.

Is the check engine lamp lite? If so what code(s) does it have?

Also do you have a pool of oil inside the intake plenium pan? Remove the air cleaner and open the butterflies and look into the bottom of the intake with a good flashlight. If an oil pool then you have an issue with the pan gasket being bad on the intake.

 

+1, it's a magnum, v6 or v8 = plenum, cat and o2 probs.

 

no check engine lights, other than the misfires and a p0171 when it sputters and ultimately dies around 1/3 tank

I reset them, and they are good to go



I don't recall any oil in the plenum last time I had the butterflies open to pour in seafoam, but I can look into that again

I don't have a a fuel pressure tester, but I think I can get one fairly cheap. would all I have to do is find a port on the fuel rail or something?