Hello LS1Tech. I normally find everything I'm looking for here by searching, but it's time to post. I spend all my time over on Camaro5, but since this isn't about how loud my exhaust is or what CAI to buy... I decided to hop over to a more technical crowd. My car is a 2012 Camaro SS/LS3.

I put a Fastlane Pipeline and VMAX ported throttle body on my car about a year ago with no tune, and after a while I noticed that the car seemed to misfire when I punched it with traction control on. It doesn't misfire with traction control off.. I find that weird. I didn't think much of it at the time. Around christmas this year I put a 3" exhaust on and started noticing that there was a very intermittent "chirp" when the car was searching a bit for idle. It would do it randomly sometimes with minutes between chirps. It was pretty faint at that time. I just figured it was an exhaust leak at the band clamps or something that opened up when the motor jumped around.

Now I've got headers and catless connections in addition to the 3" exhaust and the chirp is much more pronounced. I can hear it flutter chirp as the RPMs fall back to idle and when I turn the car off now. I can't hear the chirp from above the engine bay at all. I can hear it very clearly under the car.

The car is tuned and everything I've datalogged shows no problems. No weird knock. Pretty spot on LTFTs. Everything checks out as far as I know. I am far from an expert at examining datalogs though.

So far this is what I have tried.

1) Disconnected the catback from the connections pipes and ran open headers. The chirp was still there, only louder, and seemingly coming from the drivers side.

2) Checked all of my IM bolts, TB bolts, intake elbow connections, etc... for a vacuum leak. I haven't found anything, but I might try spraying it just to make sure.

3) I pulled the driver's side valve cover off today and inspected everything. Good oil, good springs, good rockers, good trunnions. No spongy pushrods. Everything looks great under there. I have been watching my oil pressure gauge a lot lately, and everything is normal.

4) Checked everything under the car for loose bolts. Everything is nice and tight.

What else would you guys try before pulling the heads to inspect the lifters? I'm thinking one of the rollers is getting stuck intermittently and causing the chirp. I'd rather try everything else before pulling the heads though.

Thoughts?

Here are a couple videos illustrating the problem. The first does the random chirp at about 0:32, then the flutter chirp after each rev, then again when I kill the motor. The second is a little better and is why I'm starting to think lifter.

 

Did you check your spark plug wires? Kinda sounds like an arc, turn off the shop lights and start it up (give your eyes a few minutes to adjust) and look all around the wires.

My friends truck was doing this about 3 months after he put on some aftermarket wires, it was arcing from a bad plug wire. Might explain your misfire...

 

I have had them off and on a few times now since the headers install. I haven't noticed any change, but I'd like to check the plugs anyways since it's easy. I'll check everything while I'm in there.

 

I swapped my stock intake back on and played with the throttle body blade a little. Still chirping. I spent a good 20 minutes under the car trying to track the chirp and ended up even more confused than before. It does it with the A/C on or off. It doesn't do it if I rev past 2k. It chirps right as I pull my foot off the throttle. I can't hear it at all from above the car.

I guess the next step is to re-seat the passenger side header and check under the passenger side valve cover. I'm starting to run out of ideas!

 

I went and got a stethoscope from O'Reillys today and had everyone in the store practically come out and take a guess. No one recognizes the chirping. I can hear the chirp with the stethoscope from all 4 driver-side primaries. Mechanical noises sound normal. The header isn't even close to touching anything. I would say at least a good 1/2" clearance everywhere.

Head gasket? Header with a hole in it? What are my options? I'm stumped for tonight. Someone say something brilliant!

 

Just ran into something similar at work with a Yukon with afm. Had a chirp noise that sounded like a belt that could be hear from the front of the motor all the way to the back into the trans. Used a tech 2 and activated the afm and the noise went away. Ended up being the roller tim on the lifter seized and damage to the lobe on the cam

 

That's my worst case. I can definitely hear how it might be a roller. It just doesn't catch all the time, or is becoming unstable. Do you suppose I would hear a bad roller in all 4 primaries on the stethoscope if it was a single bad roller? I think it has been doing this for a long time. It has only become concerning since I put headers on and made it so easy to hear.

What about the power steering pump? That is bolted to the same head. Maybe that is worth eliminating as a possible source first?

 

Maybe the stock ext mani hid the noise. Everyone knows you will hear more motor noise once headers are used. It might be worth the hassle of removing the intake/valley covr to try and see anything that warrants pulling the heads/liffters out.

 

I agree. I do think the noise was always there. I think i'll try pulling belts to rule out the pump, then pull the IM. If there is any damage to the lobes i can see, I might try my luck with my warranty before i tear into the motor myself. It's worth a shot anyways...

 

Well.. I'm getting closer and closer to engine work. Today I pulled the serpentine belt to eliminate the accessories. Still chirped. I re-seated the passenger side header after cleaning off the gasket (which showed no signs of a leak). I rechecked the entire length of exhaust for interference for the millionth time.

I have checked everything I can think of besides lifters/cam. I didn't have a fuel line separator today, so i'm planning on grabbing one on the way back to the shop so I can pull the intake manifold off and check the front and rear lobes. I almost hope I see jacked up lobes so I can end this ridiculous goose chase.

I'm going to visit a mechanic buddy sometime next week to see if he recognizes the noise. After that I'm thinking dealer. I hate to give up...

 

If it was under warranty, I'd deff. do that before removing ANYTHING engine wise. Hope for the best, but prepare yourself for the worst.

 

Yup. Worst case scenario i pull the motor myself when they refuse to warranty and she goes back in a healthy 416 with a better cam...

 

Or was that best case scenario?

 

I had a chirp comming from my driver side also when using a stethascope you could really hear the lifter knocking, but my lifter was making other noise before the chirp came later, once I pulled it the roller wasnt spinning and was getting worn flat, sounds like the same problem, I think your roller is sticking just enouph for the cam to side across it making the chirp, then the extra friction gets it going again. pull it now and check before you lose the bottom end.

 

If switching oil tells you something then I'd say start with the intake manifold too bud!

If you don't see anything obvious then remove that passenger head first and pull those lifters and inspect the lobes on the cam. Hoping for the best but expecting the worst for ya bud.

 

This is exactly what my imagination thinks is happening. I can't seem to pinpoint any cylinders with the scope, but I can't find anything else it could be...

I see you found me litle

I'm doing oil this evening. We'll see what happens. I'll grab a fuel line separator while I'm in there too. I didn't get around to that yesterday.

 

Pulled the manifold today. Everything looks fine of course. This chirping is PITA! Time for a new idea.

 

You sir.. have good ears. Thank you for posting. Any new lead I can get is worth its weight in gold to me. I haven't found the problem yet, but I swapped gaskets out today and failed to seat one of the spark plug wires all the way. That arcing sounded EXACTLY like my problem noise. I think I'm going to order new plugs and wires and see what happens.

 

Any resolution to this? Sounds kinda like me and my stock engine LS2 GTO...

Had an intermitted tick that sounded like an arc, on the driver's side, at idle... inexplicable misfires on cylinder #7 at about 1900rpms and less, it would be worst at idle, but also occurred to a lesser extent at 6th gear cruise.

In troubleshooting the misfire, I've replaced plugs/wires, swapped coil packs, swapped coil pack wiring, swapped injectors, did compression check... compression was good, and regardless of what I changed, the misfire stayed on #7.

Last week I removed the rockers and push rods, inspected them, and when I put them back on, the misfire is completely gone, but I now have a loud squeak/bearing sound coming from the engine... removed the belts and it's still there, so it's internal. I pulled the intake and valley cover last night, and these are the rear cam lobes:



The car has 80k miles on it... everyone that's commented on the pic so far seems to think that's abnormal wear for only 80k miles, but I wouldn't personally know.

Also, a video of the noise:



I took a mechanics stethoscope to it last night, and it's definitely coming from the #7 area.

The squeak sounds like a spinning part and not a reciprocating part like a rocker or valve, so I'm about to pull the heads to get to the lifters, but I'm looking for all input before doing that.

 

looks like normal lobe wear to me. if you turned the engine over a revolution and inspected the lobe for any SEVERE wear signs youd know. it would look like somebody took a chisel directly to the lobe and started hammering little dots in it, which is the sign of a shot cam and lifters.

as far as the noises (OPs as well), if you can remove the valvecover on the specific side you think its on, apply pressure with the wood side of a hammer to the rocker arm you think it is, and see if the noise disappears. if it does your looking at an obvious valvetrain issue.

At OP,assuming its an automatic (L92 AFM engine) if its warranty i would highly suggest it be taken to the dealership. there have been plenty of problems related to AFM lifters and actuators that cause all sorts of weird engine noises.

~Madams