I have a '93 3.0 Ranger that just failed NJ emmissions for NOx, while all other gases (HC, CO%, CO2% O%) passed easily. The NJ standard for NOx is 1227 and my truck failed with a 1851. Given only the NOx failed, I'm wondering what I should start with to try to repair it enough to pass.

 

Locate the SPOUT connector and pull the plug. This will default timing to 10* BTDC which should help lower NOx levels. Then after the test is over, you can put things back to normal.

Keep in mind too that NOx is the result of combustion tmeperatures that are too high.

 

Wouldn't an ubstucted/restricted exhaust cause higher combustion temperatures?

 

nox is created by high combustion temps. sounds like engine is running a bit lean. Check for vacuum leaks and clean the injectors check the timing. Clean the maf. late timing will defintiley cause the combustion temps to go up.

 

Thanks for input. However, I'm not familiar with the SPOUT connector.

 

Don't feel to bad a 3.0 won't pass anything else either hee hee, "sorry", I couldn't resist. The 3.slow is a good engine, just slow, I hope you get it worked out, it's a bumper when you fail e-check, I've been there, very depressing. The good part is, that it was only the gas cap.

 

IMO, add a misbehaving EGR system to your excessive NOx suspect list.

 

Pull the codes see what it will tell you. And PawPaw is right I would bet it has a 3x code and those deal with the EGR system. Ford has/had one of the worst Egr systems of any maker