|
You have a 1989 Volvo 240. Either LH-Jet 2.4 or 3.1 and EZK ignition. You have OBD-1. You say you have no EGR. Use the OBD. See the FAQ for OBD articles.
Hi NOx (oxides of nitrogen) means (in no order):
- a too lean air to fuel ratio
- a small exhaust leak that lets air enter between exhaust outlet pulses
- or indeed, as silvermine instructs, a failed catalytic converter
- A failing MAF/AMM
- A failing or failed 02 sensor.
- Too hot a spark plug.
You may have some manner of corrosion at the wire harness connectors, including the ECU wire harness connectors. Use DeOxIt at these low DC voltage unions. Or you can use SuperLube silicon grease as it is dielectric at these connectors.
Exhaust leak as ... high up at the exhaust manifold or the exhaust manifold out to header pipe in (as gasket failure at this union, or the three nuts that secure this union closed are loose).
Also, on the air intake side, you can have vacuum leaks at any point after the air filter and into the air intake ports on the cylinder head (as a air intake manifold gasket leak - you may get buy with a one-time torque check of the intake port to cylinder head retaining hardware if the gasket is not entirely brittle, or you can risk fracturing the dried and in need or replacement anyway air intake port gasket). Inspect the entire system. This brickboard.com, including the FAQ, is replete with suggestions on diagnosing and resolving vacuum leaks. Fuel injector seals ....
Please start with the OBD-1 that seemingly no one ever suggests checking. Post the socket 2 and 6 fault codes here in a reply.
A Bentley, Volvo factory OEM green service manual (free-online), the Haynes (best is the dark grey 1997 final imprint) 240 service manual tells you how to do this.
Check OBD-1 at the black box. Socket 2 is Fuel Bosch LH-Jetronic 2.4/3.1 and socket 6 is the EZK ignition. The systems work in tandem.
Check the OBD-1 before replacing parts. While not wholly exact, and the nature of these systems is to compensate to the hilt.
See the FAQ, link above. See articles on OBD.
Do you have the silver preheat hose connected between the exhaust manifold heat shield and the air filter box? You need it there to pass CA-state visual inspection. Either clog the hose at the air filter box, replace the thermostat that controls preheated air to enter the air filter box, or use a bolt and nut combo to permanently close it. Easiest to seal it be stuffing the air inlet at the bottom of the air filter box. And you have a clean air filter, yes?
There you go. Hope that helps.
Reply with questions.
cheers,
Relocating MacDuff.
--
Volvo 164: The Mightiest, most Powerful, most Beautiful Volvo Automobile Forever
|
