1990 TR failed C02 emissions

No idea but check this website from the State of New Jersey about what cars are exempt. Maybe you can qualify the car as Collector as it is not yet 25 years old to be exempt under historic.

State of New Jersey - Motor Vehicle Commission

 

What version TR?

What is the exhaust configuration downstream of the headers, and is this measured upstream of all catalytic structures or downstream of what?

 

You are welcome. I figured their had to be a way around the law legally with some sort of exception.

 

(Responding to a PM and need to send/post a pic)

There are a few different overall injection set-ups on TR, and it can be helpful in reading the tea leaves of malfunction to know which one it is. On the top of the engine at cyl #6 is a small cast plaque with the engine family and the engine serial number. This example shows a US version with engine family F113A040 and engine serial number 11687:

Image Unavailable, Please Login

Other possible engine family marking are F113A, F113A000, F113B, etc. -- what is shown as your TR engine family?

With regard to the exhaust, I'd guess that almost all have been modified in some way because a stock US TR exhaust sounds like a sewing machine (a nice sewing machine, but...), and any non-US TR legally imported to the US would have some serious exhaust changes (that may be subsequently modified again). If you do a search using a combination of terms like "precat cat", "TR exhaust gasket", etc., you should get some prior threads (with pictures) to read. Also, the TR OM is a good source with some good illustrations. Bottom line is that you'll want to know the entire foodchain from exhaust port to tailpipe -- for example, a stock US TR is:

exhaust port - header - precat (with thermocouple in outlet) - cat (with O2 sensor at inlet) - muffler - tailpipe

or another (decent IMO) possible combination is:

exhaust port - header - cat (with O2 sensor at inlet and thermocouple in outlet) - muffler - tailpipes

 

If the engine is running properly, it will measure clean even without catalysts installed. The cars run fairly clean when tuned properly.

If your CIS injection system has never had a proper servicing and adjustment, I suspect that to be the root cause of your troubles. Most of these cars haven't had a proper fuel system servicing.

It could be as simple as cleaning or replacing the injectors, could be as complex as overhauling the fuel distributors, adjusting the metering plates and setting the throttle adjustments to balance the banks.

Unless you enjoy spending money on throwing parts at the car, have someone that knows how, go through the diagnostic process of checking the CIS operation. A good overhaul and setup may really bring the car back to life and help you pass emissions testing.