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Help! My '86 Volvo won't pass smog test! (2024 Update)

I just had my 1986 740 wagon smog tested (California) after receiving a notice to have it tested at a "test-only" center. I think I read on one of the forms related to the notice that this make/model is designated by the state as having a "High Emissions Profile" and I assume that's why the test had to be performed at a test-only center.

Unfortunately the car, which I'd just had repaired (something very minor) by a Volvo specialist just before the test, and which my mechanic said was in suprisingly good mechanical condition, failed the test.

At my mechanic's suggestion I then had the oil changed and a "3-step" fuel injection service done (not by the mechanic mentioned above but elsewhere as he'd recommended, so he had no financial incentive for recommending it) andthen drive it 50-60 miles to see if that would improve the car's performance on a re-test.

Again, however, the car failed and is deemed a "gross polluter," which means I have a couple of months more to get it serviced somehow so that it can pass the next smog test or else . . . I won't be able to register/drive the car in California any more!

As I write this I'm looking at the results printout of the 2nd test and here are the results:

at 15 mph: CO2 % as measured: 14.11 O2 % as measured: 0.48 HC (PPM): 113 (maximum is 133) CO %: 0.73 as measured (maximum is 0.82) NO (PPM): 1794 as measured (maximum is 1125) RESULTS: FAIL

at 25 mph: CO2 %: 12.96 as measured O2 %: 1.55 as measured HC (PPM): 183 as measured (108 is maximum) CO %: 1.02 (0.62 is maximum) NO (PPM): 2005 (maximum is 955) RESULTS: GROSS POLLUTER

As can bee seen from the above, a big area in which the car is failing is in NO, which at 25 mph is actually double of the maximum allowed.

I would love to hear from anyone who's familiar with ways to get old cars such as my 1986 Volvo to the point where they can pass stringent smog tests.

Reply to
TomRenzi
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This is amazingly similar to a posting by "||Sergio||.

Reply to
Larry Horse

Something is very wrong, my mom's '86 with a gutted catalytic converter got something like 23 ppm HC, and significantly below all your other numbers as well. How's the idle? First thing I would do is check for vacuum leaks, then pull the injectors and make sure the path is clear and that the plastic cap hasn't cracked and broken off the end of any of them. I've seen both cause an emissions failure, on one the intake gasket was tweaked and was partially blocking one injector and on the other the plastic cap broke off so it was just pissing fuel into the cylinder. Both idled very slightly rough but not as bad as one would think for how bad the emissions ended up.

Reply to
James Sweet

Does this model have an EGR valve? If it does change it.

Reply to
Dave

I'm fairly certain it doesn't, don't think I've ever come across a Volvo that did.

Reply to
James Sweet

I always found new injector seals really helped in passing smog. You can tell if you need them by spraying a mister bottle of water near the injectors. If the engine stumbles, its sucking in the water vapor through worn seals. When you put in the new seals it won't stumble any more from this test.

Reply to
BOEING377

I've smog tested thousands of cars since 1972 all in CA. Looking at all your readings the car is in great shape tune up wise. There's only two things that will cause that high a NOX reading is the catalytic converter or the EGR valve not working. If your NOX reading was closer to normal I'd say cleaning the throttle body or driving it 50 miles might help but 2005 ppm...

Reply to
spinbag48

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