Bad Cat? How do I know?

AlanS · Post by **AlanS** » 02 Apr 2010, 13:34

Bad smell of rotten eggs...missing at higher speeds...may be a Catalytic converter? Do we have two on the 2001 S40? How do I know which one is suspect?

Volvofix1 · Post by **Volvofix1** » 02 Apr 2010, 14:03

Did you check the spark plugs and ignition coil packs and is the check engine lite on? If the engine is missfiring that will change the fuel mix and make the cat. smell. Alsohow many miles are on the car? Let me know

Dick K. from FLA

Post by **JDS60R** » 02 Apr 2010, 14:15

When the car is cool ,go undeneath and tap cat with a hammer or piece of wood. A broken up cat will sound like it has charcoal briquettes in it. You can also do a pressure test if you have the tools to drill before and after the cat. Or just place an vacuum/pressure guage on the intake and see what occurs when you accelerate.

Also you can drop the pipe after the cat and visually look at the cat itself from the back.

The vacuum guage is the easiest method.

Your car only has one cat

AlanS · Post by **AlanS** » 02 Apr 2010, 15:19

The engine misfires under load, not at easy acceleration. Engine light flashes, does not stay on. Friend did a dx and said it shows misfire in #1 and #2...

Post by **JDS60R** » 02 Apr 2010, 16:17

Sounds like coils or plugs.

Let engine cool.
Great time to replace plugs with a touch of antisieze ( use volvo plugs -for some reason these cars are finicky and we are trying to remove variables while fixing).
This should fix it .

If not mark the coils and switch them ( unplug and plug into different location) . Whne running the car see if you get a misfire code for the cylinders you switched the suspected bad coils to. If so its an easy swap. If finances allow, replace all coils as they most likely have experienced similar wear. Search around as the proper O.E. coil can be bought at significant discounts.

If the budget is tight (who's isn't right now) I am sure one of the parts recyclers above have used coils they will warranty for you.

AlanS · Post by **AlanS** » 02 Apr 2010, 18:08

I recently bought (but didn't yet install) plugs and wires. When you say "Coils", what are you referring to?

Post by **JDS60R** » 03 Apr 2010, 10:01

Can you send a pic . Vadis is displaying your car with a coil on top of each plug rather than the wire/distibutor setup.
Which engine do you have?

OK - I see it now. It has it as an option.

In that case swap over to the new set of plugs/wires/dist cap and rotor and lets see what happens. Never hurts to do a tune up.

While you have the plugs out you can pour a capful of seafoam in each cylinder and let it soak while you complete the job.

AlanS · Post by **AlanS** » 04 Apr 2010, 12:35

OK...changed the wires and plugs. The plugs had barely any electrode on them...little tiny points. I swapped the two coils with eachother (That way, if I get a misfire code, it should be the opposite as before = Like you suggested). Took it out...ran it hard... Stomped on the accelerator (which used to give me the flashing Check Engine Light), but NOTHING...dark screen. Great! Let's hope that this was the issue. No foul smell, either. It will go for inspection tomorrow, let's see what they come up with.
Thanks.