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Hiya again Uncle Bradley,
Again, try the OBD-1 for the Bosch LH-Jet (fuel) and Bosch EZK (I dunno wot 1xxK version there are) ignition.
Since your 1992 240 is not fitted with EGR, thankfully, well, other high oxides of nitrogen cause may be caused by):
- Very lean fuel to air ratio, heating up the combustion chamber beyond normal combustion temps.
- An exhaust leak high up at where the exhaust port (manifold) secures to the cylinder head, or, possibly, at the exhaust port to exhaust header pipe flange interface.
- An air intake leak between the air filter, and more so, after the AMM (or MAF) seals against the intake side of the black accordion hose and the air cylinder head air intake inlets. You may want to remove and inspect the black accordion hose. Holes can form where ever the black accordion hose contacts anything. You can reinstall and align the black accordion hose to touch nothing, if you're careful.
- And air intake leak at the fuel injector seals (they have to be bad)
- Carbon build up on valve seats and valve body preventing inlet and exhaust valve sealing closed on time.
- Spark plugs are too hot / wrong temp.
- Weak or low current or voltage condition on main fuel pump / prepump due to fuse corrosion or other corrosion on bonding faces of connector along wire harness route. (Bad ground, corrosion in fuse box.)
+ The fuel injector grounds can corrode. There is a Volvo tech
service bulletin. You'll see a hex head bolt on intake port
runners #3 & #4 that secure sheathed brown wires with
ring terms. The type stainless can cause the light aluminum
air intake port allow to corrode, and also cause the
copper wire conductor to corrode where it is crimped in
the ring terminal barrel. The Volvo TSB recommends
flowing solder into the ring term barrel, or maybe
cutting off the ring terms, and replacing them, yet
solder the fuel injector ground wire copper conductor
to the ring terminal barrels. You may want to use a
die-electric or conductive corrosion-inhibiting
grease like NoOX or De-OX, or use a durable
grease on the bonding surfaces of the fuel
injector ground wire termination. Adjust torque
(reduce) if you got some lubricant on the 10 mm
bolt heads.
- Fuel delivery issue causing anemic fuel deliver into cylinder on intake stroke. (The last thing to check, if you have to go this far.)
Do the dry stuff first, like electrics, and leave the wet stuff, like checking fuel injector rail pressure, for last.
EGR is sort of effective at reducing nitrogen oxides in exhaust, at about a mile per gallon reduced fuel economy. In spite of the 240 mass versus the very heavy B19/21/23/230 engine with relatively low power for the engine weight, a well tuned and CARED FOR Volvo 240 engine and systems, with a good catalytic converter, can burn about as cleanly as even a new or LEV (low emission vehicle). The Volvo 240 is not so good about burning as cleanly when you floor it.
If the final Volvo 240 B230 engines were built when variable valve timing was a proven design, and were fitted with VVT, well, they could perform most sprightly without turbo and maybe put out around 150-160 HP (not a whole lot).
Your oxides of nitrogen are very high for your make and year 240, so I suspect the causes listed above.
Other can suggest other causes.
Questions and comments.
Volvo "Egg-NAWG Boyeeeeeeeeeeeeeeeeeee" Mac Duff.
--
"My right to cream my morning strong black tea or coffee with egg nog on Merry Kiss My Arse morning."
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