Engine rattling/vibration happening between 3k - 3.3k

[Boofneenee]

Hi,

I recently installed a set of aftermarket UEL headers on my car and instantly noticed a rattling coming from the engine area when rev'd between 3k to 3.3k. The same rattling sound would also happen under breaking deceleration between 3 - 3.3k. The rattling does not happen anywhere else in the rpm range. The sound is loud enough that I can hear it while driving even with a loud exhaust.

Upon closer review I noticed that the rattling was the result of a roughly 1.5 inch solid diameter ring that is part of the 02 sensors. This metal ring looks almost like a washer but it is not. This ring is what creates a seal between the 02 sensor and the stock header heat shield. Now that the heat shield has been removed these rings (one on each of the two 02 sensors) sort of rest in space in the 02 sensor.

These rings are not firm or fastened from shaking while on the 02 sensor when not installed into the heat shield. Uninstalled from the heat shield you can flick it with your finger and it will rattle. While snug and flush with the heat shield it will not which is why I never noticed that the car engine was vibrating until now.

Driven insane with the sound I removed the rings from the 02 sensor and carried on. However, as of recently I have started to wonder and have become quiet obsessed with the notion that my car engine should not be vibrating at all. The fact that it vibrated enough to shake the rings only between 3 - 3.3k and nowhere else is disturbing to me. I have read in other threads that people noticed vibrations at lower speeds (2k) but never higher.

It's also concerning to me that with oodles of aftermarket headers installed using the same 02 sensors and similar style headers their has been no mention of such a rattle from other forum posters. Anyone installing a header without the heat shield should have heard the same rattling that I experienced. It is a very loud rattle like shaking a bag of pennies.

Rings removed and driving today I do not hear a rattle but their is certainly some very faint noise still happening at those rpms that I would have likely never realized unless the rattling from those rings occurred first. Maybe I am fixated and making myself hear it but the fact remains that it did vibrate or shake enough to rattle those rings and I have not heard it as a known issue for anyone else with an aftermarket header

Would someone care to give me their take of this situation and recommendation? Is this normal behavior?

thanks
Josh

[Boofneenee]

I just did a bit more research. While the engine revs to the 3k range I stared at one of the o2 sensors. Once it hits that rpm I can literally see the sensor doing a half circle back and forth! When the exhaust fumes pass through the header it must be pusbing the sensor and maybe its not an engine vibration. At least hope. i remember my mechanic told me that he didn't tighten the 02 sensors all the way in because he didn't want to strip the threads. Duh.

Question still remains.. Why only at 3k and nowhere else? Is it likely due to fumes or some type of harmonics? Is max tq occurring at 3k?

[Mr 286]

Originally Posted by Boofneenee

I just did a bit more research. While the engine revs to the 3k range I staired at one of the o2 sensors. Once it hits that rpm I can literally see the sensor doing a half circle back and forth! When the exhaust fumes pass through the header it must be pusbing the sensor and maybe its not an engine vibration. At least hope. i remember my mechanic told me that he didn't tighten the 02 sensors all the way in because he didn't want to strip the threads. Duh.

Question still remains.. Why only at 3k and nowhere else? Is it likely due to fumes or some type of harmonics? Is max tq occurring at 3k?

Max torque is at 6600 rpm on the stock engine if I recall. Technically this isn't really an issue. It's more so a question for the engine/exhaust page, and it sounds like it's due to the installation job that was done on your headers. Question, are you smelling any fumes since the install? You probably have an exhaust leak in addition to the rattle from the loose sensors. I would take it back to the mechanic and get it corrected.

[FR-S Matt]

Both my O2's aren't lose around the rings on my JDL UEL. I had to give them both a good tug with the wrench and they were fine.

[FR-S Matt]

I did have your problem at 3k rpm as well, but I lightly tightened the secondary O2 so the ring was loose. You need a large wrench to get a good tug on it.