You can install newer, and perhaps, more reliable and better performing ECUs into your 1989 700-series Turbo.

See Bill's list:

http://www.nuceng.ca/bill/volvo/database/ecu.htm

Your Bosch LH-Jet 2.2 ignition model ending in Bosch PN -541, according to Bill's list here, is compatible with -544, -554

Please keep in mind this list, or any other Bosch Fuel/Ignition ECU in RWD Volvo does not enumerate the acceptable ignition ECUs compatible with the Bosch LH-Jet ECUs in this list.

To access store OBD-1 fault codes, you need a test light or multimeter with resistance / continuity function.

It may not hurt to treat all the usual suspects of a rich running condition. Faulty wiring harness or (fuel injection coolant) sensors, faulty exhaust with leaks upstream of the O2 sensor. Faulty 02 sensor. Faulty AMM (or MAF as you like).

As you engine is a turbo, and if you have an intercooler set up on that turbo B230, please consider a full and exhaustive inspection of all vacuum and positive pressure line. At quarter-century of age, those synthetic rubber intercooler lines may be failing. The intercooler can fail, also, like a slowly failing coolant radiator. Inspect the exhaust system securing hardware, all gaskets. Please keep in mind the fragility of the turbo charge engine exhaust system. The studs in the cylinder head that anchor the exhaust manifold, and such.

Please read the innumerable articles here on the brickboard and turbobricks.com for your symptoms. You may want to use Google and target the web site using a "site:wwww.brickboard.com" (no quotes), as part of your search engine expression string.

Hope that helps.

cheers,

dud.