lol, first buy a compressor. Then buy a cut off tool. Sounds like a trip to Harbor Freight... Actually it depends on how the bolts are set up for the cat. On my old Audi, the bolts were just pass-through so I cut them off and used new bolts (ok I have a cut off tool so it tool all of 15 minutes). On my S40, the downpipe bolts are really studs so there I had to use lots of PB Blaster and used a six point socket to avoid rounding the nuts. On the really stuck ones you may have to use some heat to help (ie torch red hot, then cool and use penetrating oil). for the rounded nut if its a bolt, just cut the bolt, if its a stud, you may be stuck drilling/extracting the old stud out.

Regarding checking timing: Assuming your car allows you to adjust the timing, that requires a timing light - the light has a clip that senses the energy pulse on the #1 spark plug wire, then triggers a strobe. You should find a small hole in the bell housing which exposes the fly wheel - and there's a mark on the fly wheel for TDC. The bell housing hole will have markings on it for the various degrees before TDC. Note that most cars went to hall sensors in the early mid 80s where a small magnet on the fly wheel or cam allows a sensor to detect the engine rotation and in turn allow the computer to control the spark timing. SO if your distributor doesn't allow you to rotate the position you can't adjust the timing. Since you are so close to being in spec, I would assume the cam shaft timing is correct (sometimes the cam can jump a notch on the belt and mess up valve timing).

Last thought - the job of the catalytic converter is to essensentially complete the burning of extra HCs. High NOs are a byproduct of too hot a combustion chamber (usually caused by a lean mixture - too much air/not enough fuel). High HCs are a byproduct of not enough air for that amount of fuel. The job of the O2 sensor is to see if there's too much/little oxygen in the exhaust to tell the computer to lean or enrich the mixture. The job of the catalytic converter is to burn off any extra HCs so if its bad you may have a good NO value but a bad HC value. If you have a bad NO value and a good HC value then its likely to be a lean burn problem caused by incorrect signals going to the ECU or an intake air leak. Thats where vacuum leaks or bad sensors come into play. For example, if the engine coolant temp sensor is a bit off, the ECU may incorrectly enrich the mixture beyond what the O2 sensor can compensate for...

 

^^^^^^^^^

That post in no way describes the timing locations, method or ignition hall effect sensor on an '86 240.

OP: You should get the fasteners hot either by driving or with a torch to remove them. If that doesn't work then grind the heads off.

 

yeah, take an angle grinder to the rusted bolt heads.

 

Ouch. Hate to say I told ya so about just firing the parts cannon at it, but.... FIRE AWAY!!!



I suggest you take it to a place and have them WELD in the new cat. They shouldn't charge more than half hour of labor=$40. The hardware on yours is shot, and the flange can also fail. My flange is shot=exhaust leak=no pass=loud car=occasional backfire.


Oh, regarding timing, your car is a 1986 so BASE timing IS adjustable. 10+/- 2 degrees is spec. Did they NOT test it and put it on the report? The timing ADVANCE is controlled via the crappy Chrysler igntion box under the hood in the passenger front corner. Big black box with a vac hose going to it. I wouldn't worry about your ignition timing. I doubt that is the issue. If you don't have a timing light, you aren't gonna be able to dial it in anyways. So forget about it.

However, you SHOULD inspect the hose that goes to the igntion box. Make sure it isn't rotted out. Especially at the ends.


Fresh oil can lower HC.

Fresh cat will knock ALL the numbers down. NOX, HC, and CO. In CA they passed a law that the new cat must be approved by the state now. My theory is so many people were failing smog, so they just tossed on a $60 crappy chinese cat in order to pass, and then 6 months later their car was polluting heavily again. Theoretically, the CA approved cat will last longer. Whether, that is the case, IDK.

I have to decide whether I want to pay another $295 to put on another fresh Magnaflow cat at the same shop, wait for them to send it to magnaflow for testing, if it fails, I get my $295 back. Not really the best gamble in the world.

There are also ways to test the cat. I need to get better at it. There are cat efficiency tests that can be performed. If you aren't able to dial in timing, or get a cat off, these tests are out of the question.

Post back! GL

 

 

Take the new cat to a muffler shop!

I'd do a lot myself but this is a 10 minute job in a muffler shop vs hours and much investment in tools and frustration in your driveway; not worth the hassle...

 

Replacing JUST the cat is a headache. I bought a new cat last year, took 1 look at the aghast system and decided to just get a whole new exhaust system. It was something I knew I'd need to do eventually, so it worked out! I don't like needlessly wasting old parts that aren't shot, but the who exhaust system really was garbage.