Pre-ignition/Detonation? (LFX)

[CamiLFX]

My car has been making a rattle noise under load for a few thousand miles now. I work 6 days a week and don't have time to get under the hood and figure out what it is. I just want some input before I take it to the stealership. Thanks.

The audio in the video may not be loud enough to hear on some devices. I have to really listen for the noise on my laptop, but my iPhone makes the noise very apparent.
https://youtu.be/FjRa-eEhrbI

3.6 LFX with 78k on the odometer

[gringo]

Sounds like you need an intake valve cleaning. Ever put a catch can on it?

[DSX_Camaro]

Lots of different things it could be. If you think it's detonation or something combustion related, throw a can of seafoam in the gas tank. Check your oil, see how it looks. Knock out all the easy stuff first.


Alternatively, if you still have some warranty left, take it in ASAP. If it's warranty work they should give you a courtesy car.

[CamiLFX]

Originally Posted by DSX_Camaro

Lots of different things it could be. If you think it's detonation or something combustion related, throw a can of seafoam in the gas tank. Check your oil, see how it looks. Knock out all the easy stuff first.


Alternatively, if you still have some warranty left, take it in ASAP. If it's warranty work they should give you a courtesy car.

Thank you. I'm going to try to come to a conclusion and possibly have it fixed this weekend depending on what it is. What should I look for when checking the oil?

Edit: I'm at the very edge of my warranty. If I can't figure the problem out myself, i'll take it to the dealership on monday. I'm afraid they'll charge me $100 to tell me that nothing is wrong since there's no CEL. Lol

[CamiLFX]

Originally Posted by gringo

Sounds like you need an intake valve cleaning. Ever put a catch can on it?

No. What i've read from the controversial debate of catch can vs no catch can has left me in limbo as to what I should do. And i've been planning on an intake valve cleaning for quite some time, but I haven't found any place local to me that does it. The only places that offer the service are euro speciality shops and they charge an arm and a leg for it.

[gringo]

Originally Posted by CamiLFX

No. What i've read from the controversial debate of catch can vs no catch can has left me in limbo as to what I should do. And i've been planning on an intake valve cleaning for quite some time, but I haven't found any place local to me that does it. The only places that offer the service are euro speciality shops and they charge an arm and a leg for it.

Well, look at it this way. It can't hurt putting a catch can on it. Why have all that nasty oil flowing into your intake and coking up the valves if you don't have to.

Unless you can do it yourself or find a shop, it looks like you're up a creek without a paddle.

If the valves are indeed coked up and causing the issue , I guess you have no choice but to spend the $$$ and get it done at one of those euro shops. That is, unless you can get Kenny over on the LFX forum to do it for a nominal fee.

[Rock-It Man]

It is highly unlikely that you are experiencing detonation without the check engine light coming on, so I would be suspecting something mechanical in the exhaust.

[CamiLFX]

Originally Posted by Rock-It Man

It is highly unlikely that you are experiencing detonation without the check engine light coming on, so I would be suspecting something mechanical in the exhaust.

Thank you. I'm going to look into it now.

[CamiLFX]

Originally Posted by gringo

Well, look at it this way. It can't hurt putting a catch can on it. Why have all that nasty oil flowing into your intake and coking up the valves if you don't have to.

Unless you can do it yourself or find a shop, it looks like you're up a creek without a paddle.

If the valves are indeed coked up and causing the issue , I guess you have no choice but to spend the $$$ and get it done at one of those euro shops. That is, unless you can get Kenny over on the LFX forum to do it for a nominal fee.

I'll most likely end up doing it myself just because i'm a cheapskate, and i'll look into the catch can again soon.

[CamiLFX]

UPDATE:

I've been to the dealer and an independent shop. Dealer told me to put better gas in it, even though i've already been running Exxon 89, and the independent shop told me that it's gear clash... Anyway, I attempted to blast the carbon off of my valves. I managed to get two completely done until my media blaster started jamming. I put manifold back on and took the car to have the BG-44K 3 stage cleaning done. The car idles a lot smoother, and the butt dyno tells me that i've gained some ponies back, but the pinging noise is still present. Also tried banging the exhaust around. Doesn't seem to be a culprit there.

[qcman]

I'd run a couple tanks of premium through it to rule out ping from poor octane then take it back to the dealer and say I put the best gas in and its still the same. But the LFX should be fine on 87 let alone 89.... Don't put a catch can on until you get this sorted.

If you do I'll bet that dealer will say thats the culprit or worse void your warranty. Better safe than sorry.

[ChibiBlackSheep]

Did you pull the TB off the UIM when you pulled the manifold to clean it? I find it odd that's it just a little click when you press the pedal, and I was thinking it was a carbon-coated TB blade.

Unless my laptop and headphones aren't giving me the right sound.

[gringo]

You're probably going to have to take the intake back off again and do the rest of the valves. You can't half azz something like that and expect it to run perfect.

[DSX_Camaro]

Gas isn't going to change how it runs significantly. It's direct injection. It changes how much mid range power you'll have and that's it. On the plus side, it sounds like you don't have a real issue and just need to finish cleaning the upper intake side.


Related. Those European service shops probably know what they're doing. Good isn't cheap. Cheap isn't good.