Hey guys I am currently bringing my 2003 s40 1.9t back to life after sitting for 3 years due to major misfire from camshaft position sensor, ran pretty hard while it was misfiring so I parked it up. Here I am today, replaced plugs, about to replace injectors and coil packs to see if it fixes this cylinder 3 misfire, did a compression test and got 125 psi I would assume that’s reasonable considering the motor didn’t have the best life and has 160k on the clock, after replacing the cam sensor I got a code for crankshaft pos and camshaft pos correlation and I read up that it could just be from the extremely dark oil. Haven’t taken it on the road yet but it’s obvious it has a misfire from idle no other cylinder misfire except cyl 3, any suggestions ?

Also got a code po420 so I’m assuming one of the cats is clogged from misfiring for so long, if I gut the cat will it throw off o2 sensor readings and make my situation worse or ? Because I am in no business to throw major money at any suggestions for any of this ? Thanks guys

 

My first suggestion is to quit throwing new parts at it until you solve the misfire. Also, much (!!!) better to troubleshoot to find out if there IS a bad coil pack, then replace it with an OEM coil (aftermarket coils are cheap, and cause a lot of headaches).

125psi sounds reasonable, and doesn't seem likely to cause a misfire.

Did you replace the cam sensor with an OEM unit, or something "less"?

Also, did you gap the plugs (assuming they're not fixed gap plugs)?

Also, if you DO have a clogged cat, it's going to cause a misfire, so you can't be sure if the problem you're chasing is the chicken or the egg... If the other cylinder sharing that cat isn't misfiring, I'd try FIXING THE MISFIRE, then taking the car out for some highway miles to see if you can clear that cat (the extra air flow and heat can "burn off the junk" left from the misfire). There are fuel additive products that claim to help that process, and it looks like quite a few people have had success using them.

 

@habbyguy these are all the parts I’ve ordered, I ordered the cam sensor off fcpeuro which I figure they have pretty reputable and application friendly parts. Unfortunately all my parts are already at my house lol worse comes to worse I just have to send them back I definitely cheated out because my budget is pretty low and main goal is just to get running half decent.

 

The CPS is the most critical (most likely to fail if it's a bogus part) so you did good spending the bucks to get a "real one".

I wouldn't worry about the ignition wires - they're wires. ;-)

The injector is a bit of a risk, but I'd rather have a remanufactured injector (like the one you bought) than a no-name knock-off.

Coils - who knows? Those may be fine, and worse case, you can swap out a future bad coil easily enough.

Also, with coils, plugs and injectors, you always have the option of moving them between cylinders to see if the problem follows the part or not (something I always recommend before buying coils or injectors). If the new parts don't fix the issue, you can still do this to see if the new parts are causing a problem / misfire (it happens, and can send someone spiraling into an expensive parts-buying frenzy looking for the problem elsewhere).

 

@habbyguy okay I’ll have all the parts installed tomorrow, after installation I’m gonna clear all codes and if codes pop back up and problem proceeds I’ll come back for questions thank you so much.