VVT Tuning Noise - ADDED: Comparison Video

[uncivilised]

I had this noise with the stg2 e85 OFT tune. Now with the 4-1 EL catless header and matching overpipe i just installed, i cant hear the noise anymore. running the stock exhaust from the overpipe back so my car is not loud at all.

something to do with the acoustics in the factory header?

im no expert on this.

[Luckrider]

Originally Posted by uncivilised

I had this noise with the stg2 e85 OFT tune. Now with the 4-1 el catless header and matching overpipe i just installed, i cant hear the noise anymore. running the stock exhaust from the overpipe back so my car is not loud at all.

something to do with the acoustics in the factory header?

im no expert on this.

Is that an EL or UEL exhaust?

[uncivilised]

EL header.

[Pistol]

i got EL header
made the sound worse !!!!

[uncivilised]

which header do you have? i have the mx performance 4-1 EL header from sydney

[Pistol]

nameless performance

[steve99]

Originally Posted by Pistol

i got EL header
made the sound worse !!!!

When you installed headers you probably ran the stage 2 tune for el headers? This tune runs more timing advance and that probaably made yourknock worse. If you did not change tune catless headers will generally make you run a bit leaner again possibly increasing knock as the tune for headers also adds fuel . In Oz run 100 octane RON or pull some timing or both for low rpm high load knock

[Pistol]

Originally Posted by steve99

When you installed headers you probably ran the stage 2 tune for el headers? This tune runs more timing advance and that probaably made yourknock worse. If you did not change tune catless headers will generally make you run a bit leaner again possibly increasing knock as the tune for headers also adds fuel . In Oz run 100 octane RON or pull some timing or both for low rpm high load knock

yeah as you said I ran the stage 2 EL tune
however, i was using that same tune before the nameless header was installed

also, i have been using e85
before header and after

the mettallic sound makes me cry

[steve99]

[

QUOTE=Pistol;1668785]yeah as you said I ran the stage 2 EL tune
however, i was using that same tune before the nameless header was installed

also, i have been using e85
before header and after

the mettallic sound makes me cry[/QUOTE]

Gees knock on E85, can you see it in the logs as knock correction or drop in kc learned ?, if no sign of knock in logs then it might be something physicaly loose or hitting on exhaust, heat shields?

[Amadeus]

Originally Posted by Dezoris

Trying to get dyno done and more logging in the next week of two will post back.

Updates?

[regal]

Originally Posted by Amadeus

Updates?

The problem with this on is you would have to drive x number of miles with an aggressive vvt tune, pull the cams and mic them. Nobodies going to do that.


I can say going from A00C to B01C calibration eliminated the noise under load at 5k rpm. I was convinced the noise was just a resonance but the drastic difference in factory tunes has changed my mind.

[Dezoris]

Originally Posted by Amadeus

Updates?

Still on list to get dynos done. Bad couple of weeks.

[sprintamx]

Interesting change here: I've been running the OFT / OTS Stage 2 EL 91-93 oct tune for about 2 months (prototype catless EL header; 93 Octane all the time). The timing/valve/knock noise was very pronounced at 4K +/- rpm, and the motor seemed more "noisy" overall than when I was running the basic Stage 1 OTS tune.

I just loaded the OTS Stage 2 EL E85 tune (1.59 bin) and ran the car for the first time this morning. The 4K mechanical noises do not seem to be present and the engine "seems" more quiet and smoother overall. I doubt that the fuel system is entirely purged of the 93 octane gas just yet, and have only run the car about 4 miles / 20 minutes since the new tune. But my experience seems to be somewhat the reverse of what's being expressed in this thread . . .?

Is this just the result of the difference in the E85 vs 91/93 octane tunes? Admittedly, I have not researched this particular difference or really followed the threads.

[Gary in NJ]

Originally Posted by sprintamx

Is this just the result of the difference in the E85 vs 91/93 octane tunes? Admittedly, I have not researched this particular difference or really followed the threads.

More likely Shiv is aware of, and has read, this thread and has made changes in the cam phasing to reduce this effect.

Maybe @shiv@vishnu can respond when he returns from his honeymoon.