JGT

I had my car dyno tuned recently. The A/F ratio was right on 13.0, where the tuner said it should be.

Under WOT and higher RPMs, I am getting a sound. It isn't really a pinging. I am not getting the higher pitched, tinny, metallic sound. I have heard that classic pinging sound before, and this is not it. This is lower pitched. My first impression was that it was more of a "scraping" sound, or like velcro being ripped apart. But the more I think about it, perhaps it could still be considered to be a marble in a can sound, but without the bell like ringing, maybe as if you were shaking the can very quickly while holding all sides of it so it doesn't ring. Could this still be detonation? It lasts only for a brief moment while accelerating very hard.

I am thinking maybe this is a timing issue?

Is this something a dyno tuner should be able to get perfect while tuning the car, or is it possible for a dyno tuner to advance the timing a little too much and need to back it up later on?

Isn't this something I can do myself with the SCT?

By the way, I also heard this sound back when I had a Brenspeed tune. I thought I was just running lean and the dyno tune should fix it, but I am still getting the sound. Any help is appreciated, it has me a little worried.

Pwny

Your A/F ratio can be fine with lower octane fuel, and octane rating determines its resistance to detonation. I am unfamiliar with dyno tunes, but I'm assuming that they changed the timing for higher compression.

If you don't put higher octane fuel in with an engine that has a high compression ratio, you can detonate!

hammeron

.

JGT

The tune was for 93 octane, and that is what I currently have in the tank. I don't think it would be a case of bad gas either, since this has happened a few times with different tanks.

So, does everyone agree this sounds like detonation? Even though I am not getting the pingy metallic ringing type of sound?

grampa_stang

Maybe....

https://mustangforums.com/m_3772748/tm.htm

ClemsonAce

I have heard that noise as well in mine... so I switched to the 89 tune keeping the premium fuel and still heard it (only at wide open).. not sure what it is.

To me it sort of sounds like its gasping to suck air in (maybe scraping as you described it). Keep me updated if you figure anything out.

drbobvs

If it's truly pinging you heat, it's probably the timing. The tuner probably couldn't hear the pinging while on the dyno, those things make so much noise...

dseid2

What you are describing does not sound like pre-detonation to me.

JGT

I talked to my tuner, he is going to take a test drive with me to see if he hears it, and revise the tune if needed.

ClemsonAce, it sounds like you know what I am talking about. If it is pinging, like these guys have said, it could be from timing, and I don't think changing the octane would make a difference in that case (anyone, correct me if I am wrong).

But, if it isn't pinging/detonation, I don't know...Does pinging have to have that metallic, ringy quality to it or are there variations on this sound? I think the tuner might not totally be convinced it is detonation either, since he wanted to hear the sound for himself before making any changes.

ratnacage

Detonation can have a velcro sound to it. Having too much timing in can lead to detonation even if you're running 93 octane. Have all your tanks been filled from the same brand or station?