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Well, I was having a world of problems before this, but I’m still not out of the woods. I bought a Cobb Downpipe for my car (catted). The next day the bolt holding the alternator broke and the alternator fell down onto an accessory belt. I managed to fix that, but I had lots of vibration in my pedal around 1500rpm and especially at 3000rpm afterwards. We changed the alternator (lifetime warranty), spark plugs, accessory belts, and pcv, then cleaned the throttle body and IACV for good measure. We also noticed two hoses in the intake (post turbo) weren’t even tightened down :angry:
Things were going well for a little bit, but now there’s a weird noise happening at 1500rpm. It only happens when it’s in gear. I can’t really describe it because it’s not really a buzz, but just a rough noise right at 1500rpm. Past that everything sounds smooth.
Does anyone know what this might be? I’m reaching wits end here. So much for increasing performance 🙁
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I don’t think that’s going to have anything to do with your noise. What that code means is that you may have a bad catalytic converter which if it was bad is not likely to make any noise. Given the amount of stuff you’ve found loose already it’s probably a good idea to be on the lookout for loose fasteners on the engine and transmission for the noise.
As for the P0420 I normally look on a scanner at the O2 readings to determine if the cat is working. the front O2’s should switch back and forth rapidly past .5v when the engine is at operating temperature. The secondary O2 should stay fairly constant near .5v, if not and it fluctuates like the front O2 sensors the cat is not doing it’s job. You can also check it’s temperature with an inferred thermometer, the temp at the outlet should be 100º hotter at the outlet than the inlet of the cat if it’s working properly. Do this test also at operating temperature.
Scotty Kilmer has a video on cleaning catalytic converters, I’ve never tried it so I don’t know if it works but if it does you might be able to save yourself a great deal of money.
So, the noise was especially bad today. I threw it in reverse immediately, pulled the e-brake (so the car wouldn’t run away), and popped the hood.
The first thing I noticed was that the Turbo heatshield bolt on the bottom (the one that’s a royal B**** to get to) was completely lose and the entire thing was rattling like crazy. So, there’s one culprit.
THEN, I heard a horrible higher pitched knock noise. For a moment I expected it was in the engine itself, but I brought my ear closer and realized it was the stupid alternator I JUST replaced. And, true to the past couple months, the problem fixed itself by the time I got back to Autozone (heated up). So, they’re going to ship a new one in to me and I’ll replace that tomorrow.
Don’t buy Duralast. They are neither durable nor long lasting.
That said, I just ordered the up-pipe, gaskets, EBCS, and the other things required for the tune. That should smooth things out, since I’m guessing my Subie didn’t take well to the downpipe (though I was told it should have been fine) without a tune.
I’ll post an update after the heatshield is tightened and the junker alternator is replaced. At least it’s a lifetime warranty. :-/
Keep us posted. You might be able to put a hose clamp on the heat shield if you can find a place to gain purchase.
This will help if you have an exhaust leak.
It sounds like something is rattling away in there…. Hope it is just the heat shield against the turbo
Im not too familiar with the exhaust set up on Subarus but is the down pipe cat a sports cat you have had fitted? also has there been any change in the length of the exhaust or gap between the lambda/o2 sensors? Id also check the turbo down pipe gasket is new and correctly fitted and that your ECU map is compatible with your new exhaust set up. Some cars just throw the system into limp home mode when an inefficient cat/de-cat is installed.
Hope it all resolves soon…Subarus sound amazing with a good exhaust on them 👿
maybe also look to make sure no pullys were damaged from the alternator and make sure your downpipes bolts are tight and maybe listen in on your cat and make sure none of the media is broken?
[quote=”CorsaVXR” post=41940]It sounds like something is rattling away in there…. Hope it is just the heat shield against the turbo
Im not too familiar with the exhaust set up on Subarus but is the down pipe cat a sports cat you have had fitted? also has there been any change in the length of the exhaust or gap between the lambda/o2 sensors? Id also check the turbo down pipe gasket is new and correctly fitted and that your ECU map is compatible with your new exhaust set up. Some cars just throw the system into limp home mode when an inefficient cat/de-cat is installed.
Hope it all resolves soon…Subarus sound amazing with a good exhaust on them :evil:[/quote]
Yes, it’s a Cobb 3″ catted downpipe. To my knowledge, the Cobb downpipe has it in the same position, or close to it. Unfortunately, I have been throwing a PO420 (cat efficiency) lately, which is common for catless setups. I’ve been told the car doesn’t go into limp mode for this code. I’m just disappointed it’s happening even with the catted version. I’m pretty sure I have an exhaust leak, but I have a feeling it will be resolved after I get the rest of the parts on. I have a new up-pipe (pipe from headers to turbo), Electronic boost control solenoid, and a open-source tune to throw on it. You have to drop the headers and downpipe to get it on and I have new beefier gaskets for all the connections. Hopefully that resolves that issue. Not to mention, the tune should make the car run better overall.
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