Emission testing advice - Ford Ranger

I'm not really sure where the best place to post this since it really isn't a 3rd gen concern. However, I figured people here might have some advice.

The old truck that I replaced with my 3rd gen failed emissions for the first time. I was wondering if there were any suggestions on fuel additives I might try to get it past emission. I changed the oil today but thought maybe there was something else "fairly" cheap I could do. The truck isn't worth much so I really don't want to spend a lot.

Also when I did emissions the technician had me step on the gas and run it at 2k. I've never had them do this before. Anyone think this could have caused it to fail? Maybe I'm reaching?

 

I'm in TN as well. What exactly failed on the test? They should be able to tell you what the problem is. Is it exhaust, codes, etc.?

 

Usually their results indicate areas that need addressing. I would start with the report first. It's best to look at it with a grain of salt too

 

In addition to the rejection report tell us more about the "old truck":

• what MY;
• what engine;
• how many miles;
• when was it last tuned up;
• how old is the gasoline (E-10 can go bad in 2 to 3 months and foul up emissions);

All else fails move to Florida, no emissions testing here...

 

93 Ford ranger with a 4L V6. It failed because of unburnt fuel. It has 250k, I changed the spark plugs about 6 months ago.

 

Have the fuel injectors ever been replaced? I'd run some seafoam through it and see if that helps. Any codes?

 

What do the plug wires look like, newish or old and ratty?

Check the manifold vacuum and compare the gauge behaviour to this chart:



However better yet, and before chasing ignition and fueling too far, I would run a check the compression (dry and wet). If the dry and wet numbers are pretty much the same, but low, do a leak down test.

"unburned fuel" could be a very weak spark, but more likely it's low compression due to worn rings or valve leakage.

 

Unless you get a code saying different, at high mileage it's almost always a worn out cat.