300te failed inspection
 

1989 300te...failed New York State Inspection...Hydrocarbons too high (HC)...1.11gpm, limits 0.80.
I have no idea where to start. I have regular fuel in the car, does that matter? I have 30 days to get this thing up to snuff...

High HC is usually due to unburned fuel, or sometimes due to oil consumption. Usually, when the HC is high from unburned fuel, the CO is high too. Where was your CO? Does the car smoke any from oil consumption or have oil deposits on the plugs? The catalytic converter's job among others it to burn the unburned HC that is normal in the exhaust. So to pass emissions your engine must not put out too much HC, the catalyst must burn what HC is put out, and there can't be additional HC from oil consumption.

So there are three likely scenarios:

1, your fuel mixture is adjusted too rich , or is runnig too rich from a malfunction

2, your engine is burning oil causing high HC readings

3, your catalytic converter may have lost its efficiency and isn't burning the HC

Un Burnt fuel can also be a result of poor secondary ignition (from the coil to the plugs), have you checked your cap, rotor, plug wires and plugs yet?

Start with the inexpensive stuff first, before moving on to cats etc. That reminds me, did you take your car for a 20-30 minute pretest run and heat the cat(s) up?... It can help quite a bit

Be sure you have the correct non- resistor plugs and a fresh oil change.

Notwithstanding your need to address the mechanical situation eventually, if you want to lower your HC enough to pass, add a liter of isopropyl alcohol to half a tank, run it like crazy for 30 minutes and end up at the testing station. Worked for me. And eventually I replaced an o2 sensor. Please post your results.

isopropyl contains water it's sold in 70% and 90% I would stay away from that. I would add denatured ethanol instead it's a better oxidizer and has no water. Can be found at local marine stores and some hardware stores.

You are very close to passing as it is. 1.11gpm is very close to 0.80. I would add some NO smoke product to oil help prevent oil passin seals into combustion chamber. I would lean the car out by pulling a vacum line off adds air leans mixture, add ethanol or methanol make sure car has been run for good 20 minutes and retest. Should pass.