bgoetz

Well it has been a good run, without too many issues with this car, but here I am with a dreaded bore scoring type sound. Except I am not convinced that is what it is and want to eliminate any other possibilities first. Details:

• Car has been driving awesome last UOA was great.
• Running low on gas but not super low fuel light just came on
• Noticed that at a stop the car felt like it was about to stall out on me and thought maybe my fuel gauge had lied and I was running out of fuel. Car seemed to be missing and knocking pretty bad and I barely made it to the gas station.
• Refueled and was greeted by a distinct knock/rattle upon startup. Car continued to run poorly on the 2 mile drive home.
• The sound seems to be coming from the left side of the engine and goes away when the car hits 2k rpms or more then comes back when it drops below (listen in video).
• Zero smoke, oil consumption or other indicators of bore scoring.

Yes I realize it could be bore scoring, but it seems odd that it would just come completely out of nowhere and be instantly bad enough to cause the car to run so poorly with no other symptoms. I also find it strange that above 2k rpms it is like the sound just vanishes.

I can’t seem to get my Durametric program working on my computer so I need to grab a friends and see if there are any codes in the background. A quick scan with my Bluetooth dongle reveled no codes pending.

At this point I am afraid to drive it more until I get this issue sorted because I don’t want to break it anymore than it already might be.

sandwedge

Other than the ticking/knocking sound you say the car "continued to run poorly". Can you elaborate on that? What other symptoms?

bgoetz

Like it is misfiring, it stumbles and nearly stalls out, not constantly either though, so not every moment it runs just somewhat random, but when it is running “smooth” it still knocks and definitely doesn’t run as smooth as it did. No CEL and I never did get Durametric going on my computer, but will get a friends CP tonight. I suspect I see misfires on bank 1 somewhere.

The other odd symptom was that after doing that video on a semi cold start (the car had ran 1hr prior) the sound almost went away when I pulled back into the garage.

The only things that come to my mind are:

1. Bad coil, but why would the sound go away above 2k rpms and why would it go away when pulling back into the garage

2. Some type of oil driven tensioner failure causing chain slap and the car to pull timing due to the knock

3. Stuck lifter, would that cause the poor running?

4. Scored cylinder although if it were bad enough to have running issues I would expect to see smoke from the exhaust and would have though it would have had symptoms prior

5. Spun rod bearing, but why and why so sudden

Fullyield

Get a Steelman Electronic Ear and isolate sound to a specific component or location. Just guessing until you do as it could be numerous different issues.

bgoetz

I did try a stethoscope and it is loud enough that it is hard to isolate beyond bank 1. If I were to pinpoint I would say cylinder 2 area.

Hilltopper

The fuel tank on four wheel drive has upside down "U" splitting tank in 2 and low fuel will trigger your problem if you have four wheel as fuel sloshes in low fuel 2 sides. Ask me how I know-happened and I learned to never let fuel get low.

Scalp_em

I really hope it’s something else…but from this untrained unknowledgeable ear it sounds just like the bore score sound. Might be worth while to get scoped just to be sure. How many miles and curious to see what your last UOA looks like if you don’t mind sharing…how were your tailpipes? Odd that u didn’t have any other symptoms like oil consumption or smoke etc…

***edit re watched video and saw you were @ 60431miles.

997.2GTS

This does not appear to have the characteristics of bore score. That's more of a dull knock and the OPs UOA was good - and it would not be if scoring was occurring. I'm optimistic it's something else, and it happened 'suddenly' - again, not a symptom of bore score.

OP - did you cut open your last filter and check for debris? Doubtful you would find any if the UOA is good.

I would dive deeper into diagnostics before panicking. Good luck!

bgoetz

I would agree it does not sound good, although the sudden onset and zero prior symptoms makes me hesitant. UOA was perfect no issues. There had been some silicone that had dropped considerably over the past few changes, but I think that was due to having the IMS done and a bit of fresh sealant as it started immediately after. The silicone while notable wasn’t real high, especially this last time (9ppm I think). The cylinders were scoped at 45k when I had the IMS done and came back good. There are zero other symptoms like sooty tail pipe.

Scalp_em

Ok well that really doesn’t make sense for bore score…have you done anything to the exhaust recently(headers etc)? I know sometimes if there is a leak somewhere it can make a noise like a tapping sound…following and wish u luck…

Fullyield

Well, a $15 mechanics stethoscope like they sell at Harbor Freight or Walmart will not work as you learned. You need to use a Steelman Electronic Ear which is why it was specified. It will allow you to isolate the sound to a specific pump, pulley or a particular cylinder. A cheap stethoscope will not. Ask me how I know. Best wishes.

rtl5009

Doesn’t sound like bore score to me. Hard to tell what it is, it’s not good but not bore score IMO.

Optionman1

Put your phone on the ground under both banks and record the car at idle. Hard to hear on the video you posted.

Bruce In Philly

2009 C2S 174K miles

Some items that may help:

https://rennlist.com/forums/997-foru...ing-noise.html

In one of Jake's videos, he isolates the tick using a stethoscope. From underneath, he probes each cylinder. It was clear. I suspect you are not putting the stethoscope in the right places. I don't know which video it was.... you can go fishing on his YouTube channel.

Peace
Bruce in Philly (now Atlanta)

bgoetz

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