Having a problem with passing emissions got to do with the fuel injectors or something

Miss-fire on cylinder number 1. The picture shows location of cylinder number 1. Check for spark at number 1 cylinder. There are ignition based misfires--fuel based misfires--emission based misfires, I'm sure I'm leaving something out. You need to be aware the computer may disable the fuel injector if misfire detected on that cylinder, that's normal. Trying to protect the cat. If fuel injector is disabled have to decide if normal operation or something wrong with fuel injector or wiring circuit.

The codes mean the cylinders are not producing power, which could also be fuel injector problems, or something else.

What is the reason that it wont pass? High levels of WHAT? What is the year and make and model? Are there any check engine light codes?

what did it not pass for .

Have your fuel injection pump calibrated. Might as well have it checked for leaking injectors.

Most modern vehicles have 2 catalytic converters, there may be one located at the exhaust manifold, or be what's called a resonator. The resonator will look almost like a cherry bomb muffler, this is a crucial part of exhaust emissions.

IF DECELERATION FUEL REDUCTION SYSTEM IS NOT OPERATING, FUEL ECONOMY WILL BE REDUCED WHILE HC AND CO EMISSIONS ARE INCREASD.SEE ON MANY ENGINES WITH DECELERATION FUEL REDUCTION SYSTEMS THE PCM STOPS GROUNDING THE INJECTORS IN A SPECIFIC RPM, DURING DECELERATION.

it all depends on how much diesel remained in the tank before the gasoline was added, and how new and sophisticated the diesel engine is. In a 2007 or newer clean diesel engine, any amount of gasoline will probably damage the sensitive emissions control components (DPF, OxyCat and SCR) and system. In older engines with much less sophisticated and "touchy" emissions systems, a lightly diluted (say 90 percent diesel/10 percent gasoline) mix would probably pass through with little or no detriment. It might simply cause reduced engine power, perhaps a bit more noise, and possibly a sharp warning from the emissions sensors that detect something other than pure diesel exhaust. It's high concentrations of gasoline that spell real trouble. Whether a modern clean CRD diesel or an old indirect injection unit, burning straight gasoline or highly diluted diesel fuel will almost certainly result in catastrophic damage to the mighty diesel engine.

This is a problem with your Cat converter Replacing car will then pass the emissions test, Air and fuel mixture if it was wrong your car wouldn't respond correctly and you would know something is wrong before you did any emissions tests, Also garage would have tweaked it for free for you as only takes a couple of mins

Sounds like you need to replace your oxygen sensors.  If you have a four cylinder I think you only have one oxygen sensor and the six cylinder I know has 2.  You can check that out at your local parts store.  Anyway, the oxygen sensor helps the computers in your car make sure that you are getting the correct amount of fuel and air during combustion thus controlling your emissions.  I would think that if you haven't replace these in a while that is what is probably keeping you from passing your test.  Change the oxygen sensors and put a bottle of good fuel injector cleaner in a full tank of gas and you should be good to go.  I would suggest Greased Lightening fuel injector cleaner that can be purchased at Napa and O'Reilley Auto Parts.  Let me know if you have any other questions.  Thanks for an honest rating and for using FixYa!