Hello!

I have a really tough 1988' Volvo 240 DL Wagon that I've owned for about five years and has passed smog many times before. Today it failed. It was a rainy day.

Nitrous Oxide reading was nearly failing at 15mph and over by about 70ppm at 25mph. Also, it was idling around 1k rpms, it was supposed to idle at no more than 750.

I feel like I can fix the idling problem by just adjusting the throttle cable under the hood right?

As for the nitrous, dude said Oxygen sensor, catalytic convertor, or possibly even a tuneup.

Car hasn't been tuned up in SOME time.. who knows really. Is that something I should try doing myself and then bring it back? Could the rain have messed up the test? My front tires are pretty bald.

Thank you for the help!

 

I messed with the idle and checked some other things. I twisted the upper throttle cable in so that the butterfly seated, and I also screwed the idle adjuster in all the way so that it idles lowest. I sprayed starter fluid around the intake area, the hoses and such, while the car was idling to detect for vacuum leaks, nothing happened. I can't really tell where else to spray starter fluid to test for leaks, but I haven't been able to find any, I sprayed some random hoses here and there in case they could be part of the problem (I sound pretty amateur right now I know).

I tried to check my ignition timing with a timing light and it seems okay, but I don't really know how to read the notches on the front of the pulley. I know that it's supposed to be 10-14 degrees BTDC at 750rpms, but I don't understand what the markings on the piece of plastic above the pulley, where you're supposed to aim the light, are supposed to mean. It's between some of the lines, but I don't get what I'm looking for...

I also pulled the dist cap, it looks great underneath, but the distributor rotor is a bit corroded, although I can't seem to pull it off!

Any help would be awesome. Thanks.

 

I would start by doing a full tuneup - plugs, cap, rotor. Then set the timing properly according to the manual. You can find Volvo green books on kjet.org. From there, set the idle properly according to the procedure in the manual. If you have an EGR valve, check it. Pull a vacuum on it using a mighty vac. If the engine doesn't bog down when you pull the vacuum, then the tube from the exhaust to valve is clogged and must be cleaned.