So i got the new truck smogged today, 92 f250, 460, 5speed, 4x4

my Readings were:

@ idle HydroCarbons 225ppm, Allowed 150ppm (FAIL)
CO % 1.3 measured, allowed 1.2 (Fail)
@ 2500 RPM
HC 53ppm, Allowed 150 (PASS)
CO% 1.61 measured, Allowed 1.5 (Fail)

All the functional and Visual stuff was a pass just the sniffer failed me.

This was after all the obvious pre smog stuff, long warm up cruise, fresh oil, and 91 oct in one of the tanks (holy hell was that shock at the pump)

Could this be a cat issue?

 

I think it would have been better off running regular 87 octane fuel. I'm not sure if that would have really changed much though.

Has it had a tune up fairly recently?

 

yes it has had a tune up, msd cap and rotor, new plug wires, plugs, air filter, all fluids changed.

Im tempted to run seafoam through it to see if that will clean up the valves

 

Hi dont know the exact situation, but mostly this happens because the valve stems leak oil to the cylinders, I had the same problem here in Europe. Try it on the ethanol, makes less polution, just for the exam, or put in the engine denser oil, just for the exam and then change it again. And by the way on europanien cars there is mixture screw dont know about us cars. Of course I know it is injection, but has to have it somewhere, plugged but should be there. Also correct timing affects the emissions, check that. If it has a catalytic converter with Lambda sond, change that. My father used to work for MOT here in Europe. The engine is not bad, just the mixture is slightly rich for some reason. Hope I helped.

 

Dont run anything to clean the valves, through years it has a deposits on it and by cleaning it u have a big chance to even worsen it,dissolving the deposits resulting in bad sealing, I wouldnt do that. Nothing wrong with the valves as far as I know.

 

Ethanol isnt available here in CA, at least not at any station locally (within 200 miles)

Could the o2 sensor be bad without throwing a code?

 

And by last run the gasoline it was made for, u are lucky to have 87 octane gasoline around, here in Europe only 91 and WWII jeeps dont like it at all, smoking, ticking. The more octane gasoline for engine that wasnt built for it, u have to retard the timing otherwise the ignition ignites premature and the mixture is not as effective and produces a lot of CO and HC.

 

Can be bad for sure, common case, change it and for 80 procent u are through, I work as a mechanic and it is a common fault, O2 sensor is responsible for mixture.

 

And of course catalytic converter, but no way to check it, just replace and see.

 

U know throwing codes is sometimes pointless, through the years I solved many cars that didnt throw a code but were not performing good, then u need a real experienced mechanic not just a code reader and changer.I do not want to offense anybody, I admire people working by their hands trying to do some work by themselves. Try the O2 sensor, it is not that expensive, but usually rusted and by unsrewing usually comes a threading.

 

And at last just asking any chance to pay them to pass it? I know u arent use to it, but corruption rules the Europe. Every mechanic here has a friend at MOT. Just asking, here it is a common practise.

 

Check for codes. There can be some stored without setting the check engine light off.

 

I dont think it's the O2 sensor, but they do have a life span.. whats the mileage? Open loop (idle) doesnt use O2 sensor for fueling. Closed loop (on the gas) does. Higher octane will just allow you to run more timing, but without a knock sensor your not getting any benefit from the higher octane fuel. What were the NOX numbers?

 

O2s typically need to be replaced every 60,000-100,000 miles. Their response time slows as they age.

 

How is your PCV valve?