Intermittent engine 'rattle' when accelerating

[mjfulk]

Originally Posted by strat61caster

Once again, sounds like VVT overlap from the OFT tune.

Happens at 4s-5s, 7s-8s, 12s, a little at 24s, 38s-42s etc. right?

If you want to get rid of it you'll need to change your current tune to a custom map (you could pay Shiv at OFT for remote tuning work, he should know what to change to get rid of it which will likely result in some power loss in that 3.5k-4.5k range) or go back to stock. Don't believe me? Drain the tank, put 93 octane in it and flash back to the stock map on your OFT, noise gone. You can even flash to OFT's stage 1 map and hear it come right back. I believe most tuners say it is harmless, whether you trust that is up to you.

Once again in case you didn't bother to read it the first time I linked it for you.
http://www.ft86club.com/forums/showthread.php?t=59475

I've read the threads on VVT noise from various tunes but I'm not convinced it's what I'm experiencing. First the intermittent nature of the noise. Why would it come and go from day to day drive to drive and be happening more frequently over the last several months. Second, and more importantly, the noise was occurring before I installed the tune and headers when it was completely stock. The last couple times I've flashed back to the stock tune it occurs with the same frequency as with the tune.

I'm so desperate to get this addressed I decided to upload the video, complete with my gross leg and all.

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[strat61caster]

Originally Posted by mjfulk

I'm so desperate to get this addressed I decided to upload the video, complete with my gross leg and all.

Well it sounds precisely like my car on OFT tune, you have to nail the load and throttle position, repeatable but sometimes it can be tricky to coax out.

If it's not that then I'd go with what others have said, some heat shield/undertray is loose and needs to be tightened.

Good luck.

[mjfulk]

Originally Posted by strat61caster

Well it sounds precisely like my car on OFT tune, you have to nail the load and throttle position, repeatable but sometimes it can be tricky to coax out.

If it's not that then I'd go with what others have said, some heat shield/undertray is loose and needs to be tightened.

Good luck.

I swung by the shop this afternoon and the head tech went for a ride with me. After hearing the noise a handful of times he's almost certain it's valve noise. With that being the case the question remains why its occurring more frequently and with the stock tune and we'll as the OFT tunes. If it continues to get worse is it a problem that needs to be addressed and if so how. Feels good to get closer to the answer but still some unknowns remain.

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[humfrz]

Originally Posted by mjfulk

I swung by the shop this afternoon and the head tech went for a ride with me. After hearing the noise a handful of times he's almost certain it's valve noise. With that being the case the question remains why its occurring more frequently and with the stock tune and we'll as the OFT tunes. If it continues to get worse is it a problem that needs to be addressed and if so how. Feels good to get closer to the answer but still some unknowns remain.

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Did he expound on that .... ??

If it does have something to do with the valves, yes, it should be taken care of.

What should be done .. ?? That would depend on what's wrong.

Most likely the head on that side would have to be taken off and the valve train inspected.

If I were you, I'd still check for something rattling, before I tore into the engine.


humfrz

[mjfulk]

He mentioned the VVT system as the likely source. I'll apologize here for my ignorance concerning VVT in general but he mentioned several things in the system that could be the cause. I asked if he thought it could be a panel on the bottom or something in the exhaust system. His response was that the rate of the rattle and tone made him pretty sure it wasn't either of those but rather a valve issue. I still plan on getting under the car this weekend to see if there is anything obvious.

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[steve99]

Originally Posted by mjfulk

He mentioned the VVT system as the likely source. I'll apologize here for my ignorance concerning VVT in general but he mentioned several things in the system that could be the cause. I asked if he thought it could be a panel on the bottom or something in the exhaust system. His response was that the rate of the rattle and tone made him pretty sure it wasn't either of those but rather a valve issue. I still plan on getting under the car this weekend to see if there is anything obvious.

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http://www.ft86club.com/forums/showthread.php?t=59475

[Syche]

histortically rattle at 3K, sounds like its from engine bay and its manufactured by the six star oil eater, its prob a heat shield.

[mjfulk]

Originally Posted by Syche

histortically rattle at 3K, sounds like its from engine bay and its manufactured by the six star oil eater, its prob a heat shield.

I was able to get under the car and took the two bottom panels off. The metal one under the engine and fiberglass one under the transmission. After driving around for a day and a half the noise remained unchanged. I looked at the exhaust and didn't see anything obvious that would be causing the issue. I also had the chance to change the tune between the four tunes with the oft.. Stg 1 EL, UEL, e85 EL, and e85 UEL (after filling up with e85 and following the recommended ecu learning procedures). The noise is present and random with each tune. Perhaps it occurs more often with stg1 EL but that could have just been the day. On that note any thoughts on the tune to use with a catted header? Finally I also data logged for the first time this morning with the oft tablet. What should I be looking for concerning knock?
Thanks

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[mav1178]

Originally Posted by mjfulk

I was able to get under the car and took the two bottom panels off. The metal one under the engine and fiberglass one under the transmission. After driving around for a day and a half the noise remained unchanged. I looked at the exhaust and didn't see anything obvious that would be causing the issue.

Did you take off the heat shields on the overpipe/front pipe? The heat shields have several overlapping components that may cause rattling.

Also, it is rare but there is the remote possibility that the front pipe catalytic converter is bad. Mine was replaced under warranty because the honeycomb assembly came apart, was not making noise but was loose when you take off the front pipe.

-alex

[mjfulk]

Originally Posted by mav1178

Did you take off the heat shields on the overpipe/front pipe? The heat shields have several overlapping components that may cause rattling.

Also, it is rare but there is the remote possibility that the front pipe catalytic converter is bad. Mine was replaced under warranty because the honeycomb assembly came apart, was not making noise but was loose when you take off the front pipe.

-alex

Thanks Alex, I'll take a look at the heatshields this weekend. In the meantime I've been doing some research on the data logging I did today. My values for FLKC and Adv Multiplier (I assume that is IAM) are constant at 0 and 1 respectively. My only concern is that they are exactly 1 and 0 without any change. Is that correct or an indication those parameters aren't reading?

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[Jordanwolf]

Originally Posted by humfrz

Did he expound on that .... ??

If it does have something to do with the valves, yes, it should be taken care of.

What should be done .. ?? That would depend on what's wrong.

Most likely the head on that side would have to be taken off and the valve train inspected.

If I were you, I'd still check for something rattling, before I tore into the engine.


humfrz

Holy shit, that word pounded me in the face, I wasn't ready for that fancy word wtf

[humfrz]

Originally Posted by Jordanwolf

Holy shit, that word pounded me in the face, I wasn't ready for that fancy word wtf

Ya, I got that word out of mrs humfrs's big book of words ......


humfrz

[Syche]

Originally Posted by mjfulk

I was able to get under the car and took the two bottom panels off. The metal one under the engine and fiberglass one under the transmission. After driving around for a day and a half the noise remained unchanged. I looked at the exhaust and didn't see anything obvious that would be causing the issue. I also had the chance to change the tune between the four tunes with the oft.. Stg 1 EL, UEL, e85 EL, and e85 UEL (after filling up with e85 and following the recommended ecu learning procedures). The noise is present and random with each tune. Perhaps it occurs more often with stg1 EL but that could have just been the day. On that note any thoughts on the tune to use with a catted header? Finally I also data logged for the first time this morning with the oft tablet. What should I be looking for concerning knock?
Thanks

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not sure what kind of info it can show you, but your looking for knock related or kknock sensor related if your concerned with knock ... but knock is pretty distinct, look up an video of a subaru knocking and youll be able to tell immediately

[Herrera937]

Hello, I have the same problem in my BRZ. Could you solve it?