4 captured repliesDiscussion pagination complete · Source accounts, not a confirmed diagnosis
THIS DISCUSSION / SOURCE-DERIVED OVERVIEW
Discussion summary
YOUR RESEARCH99 C2 - Odd Noise at higher RPM
Reported or suspected cause
cats
Suggestion or failed attempt
No successful repair reported for this finding.
0
Identified cause
1
Suspected cause
0
Reported fixes
Read evidence and context
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Discussions that suspect a cause
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Suspected cause · Original poster
I figured it was the cats, but most of the threads that talk about them failing that had videos, they are no longer available.
Leading evidence: 'cats' (no explicit attributable resolution; this is a reported action or suggestion). Across 1 matching discussions, the most frequently mentioned possible cause is 'cats' (1 discussions; 0 report identifying it and 1 suggest it). The most frequently discussed action is 'Test with a vacuum gage the pressure' (1 discussions). For that action, 0 discussions report a resolution and 0 report an unsuccessful attempt. No action has an explicit, attributable resolution report under the current rules. These are forum reports and suggestions, not a confirmed diagnosis.
Source reports, not a diagnosis or a success probability. Counts refer to discussions and can overlap.
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Suspected cause · Original poster
Since I already had the bypass pipes with 4 oxygen sensors I decided that was probably the easiest to change and most likely to be the cause of the noise as the cats have 155,000km on them.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
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Suggestion
You can pressure test with a vacuum gage the pressure before the cat should be nearly 0.
Explicit resolution reports before identified causes, performed actions and suggestions. Within each level, matching component labels precede direct query mentions and inherited thread context; successful versus unsuccessful discussion counts, owner confirmations and independent discussion support determine order. This is not a probability of success.
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Suggestion
Easiest way is to remove the 02 sensor and use a adapter to extend the sensor out and drill a small hole in the adapter/extension to push the vacuum gage in to.
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suggestion
Easiest way is to remove the 02 sensor and use a adapter to extend the sensor out and drill a small hole in the adapter/extension to push the vacuum gage in to.
0 original-poster resolution reports. Counts can overlap; they are not unique people or a success rate.
0 discussions have direct query context; 0 report a fix in that context. Other evidence may inherit the discussion’s subject.
Suspected cause · Original poster
Since I already had the bypass pipes with 4 oxygen sensors I decided that was probably the easiest to change and most likely to be the cause of the noise as the cats have 155,000km on them.
Counts describe captured discussions, not unique people or a diagnosis. Author identities are not reliably stored. Exact duplicate evidence is counted once across matching discussions; one discussion counts at most once per action/state. Multiple repairs reported together remain a combination. Suggestions and failed attempts do not establish a fix. Matches cover whole discussions and can include related faults, model variants and incomplete threads.
4 eligible posts · 0 unverified posts · 1 discussions match the subject in their title or opening post.
Rennlist: 1 discussions
0 evidence records excluded for query context · 0 excluded by outcome qualification · 0 adjusted by outcome qualification.
1 acknowledgements have no verified action link; they do not establish a repair result.
Outcome without a verified action link
Luckily that solved the problem and it wasn't the alternator itself.
Hey Everyone,
I started noticing a noise inside the cabin, particularly after the car is warmed up, on the freeway if I accelerated under load at about 4000rpm. It sounded kind of like a hollow metallic pining or something..
I checked it in the garage, and when the car was idle and cold I didn't really hear it. If I revved it to about 3500rpm I could hear the noise. As the car continued to warm up while I was trying to listen to the mufflers, cats, etc I noticed the noise becoming present at lower revs, coming on around 2500rpm.
I finally took a video with my phone on the ground, upon playback I can make it out at idle, but I think only when it is warm, and its very noticeable when revving it.
Here is the video
https://www.youtube.com/shorts/CEqW1eyuwVQ
So far I've knocked the mufflers and cats with a rubber mallet, I don't hear anything rattling around.
My plan is to try the following the next chance I get:
Remove the belt and listen to see if the noise is still present. Would it be ok to rev to 3500rpm with the belt off?
Remove the rear bumper and heatshields to isolate a rattling heatshield
I have my old stock mufflers and some cat bypass pipes, so can swap out the various components to isolate the issue. This would be easy except for what I assume will be plenty of rusty hardware as I've daily driven the car through 6 Alberta winters now.
Looking for any ideas or thoughts on what else to check for.
Exactly how a failing cat converter sounds. You can pressure test with a vacuum gage the pressure before the cat should be nearly 0.
Easiest way is to remove the 02 sensor and use a adapter to extend the sensor out and drill a small hole in the adapter/extension to push the vacuum gage in to.
The "Spark Plug Fouling preventers" that folks use to fool the 02 to non realize its cats are missing is the one I use. cheap on flea-bay.
You need to drill the end out where the 1/8 or so hole is so it allows the pressure to get in.
I figured it was the cats, but most of the threads that talk about them failing that had videos, they are no longer available.
I'm going to spray some liquid wrench on the bolts over the next few days to let them soak.
I had to put chasing this down onto the back burner for the past month or so as I started suffering from low voltage once my car got up to operating temp. I had to order a new voltage regulator and y cable. Luckily that solved the problem and it wasn't the alternator itself.
Anyways, tonight I finally got back to the exhaust noise. Since I already had the bypass pipes with 4 oxygen sensors I decided that was probably the easiest to change and most likely to be the cause of the noise as the cats have 155,000km on them.
The good news is I didn't snap any of my existing catalytic converter bolts off while taking them out, but unfortunately the noise is still present with the cat bypass pipes installed.
So next will be to take the rear bumper and heatshields off and go for a drive. If it's still present then I guess the mufflers are the next target.
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