POS7

I was cruising on the freeway & decided to open it up. I was around 4k rpms at .73 boost (recorded on the pfc) when I heard 2 distinct pops from the engine bay. It sounded kind of like backfire pops, but from the engine bay. I immediately eased off the throttle. The car seemed to run fine after & idled ok. Still got -4xx vac at idle.

After I check the peak knock, it read that I knocked at 132. From what I've read here, its bad, but not that bad. Usually, i don't knock over 50 even under heavy acceleration. I've seen reports of others at 170 or so upon detonation.

My mods are PFC (base map), dp, cb exhaust, pettit cool charge 2 intercooler, and intake.

Just thought I might share this because I know there's a lot of other people with similar mods. This is the first time it happened, and only happened after I switched from stock smic to the pettit smic. I guess I'll probably be changing back to the stock intercooler for now Its strange because the pettit ic uses the stock bends. I didn't think that the pettit would flow that much more air (and cooler air) over the stock ic.

G's 3rd Gen

iTrader: (11)

severe detonation sounds like someone banging a hammer against metal in your engine bay. Usually can feel alittle hestitaon when it happens. That is what mine did when it spit out a rear apex seal on near freezing December night 3 years ago..

dgeesaman

iTrader: (7)

Yeah but were you feeling the detonation, or the apex seal letting go?

Dave

POS7

^ are you talking to me? I'm pretty sure it was detonation. I felt the car stumble slightly while it was happening, and the knock went way up. If the apex let go, I would have lost all power immediately.

dgeesaman

iTrader: (7)

Naw, I meant the hammer on metal thing. THAT is the kind of thing that would make metal-metal sounds. I would expect detonation to make a thumping or popping sound, at least that's what I recall hearing about it.

Dave

2FAST7S

Yup, Hammer on metal...I've never actually heard it but i did blow a n/a due to fuel starvation. Once they let go, they usually shut off and its near impossible to get them going again.
I've hit 198 on the knock readout of the pfc commander...no detonation though. Its just not accurate enough to use it as a "gauge".

How many miles do you have on the motor???? I doubt you had detonation, most likely misfire of some sort judging by the sound you describe...distinct pop is a far cry from a hammer on metal sound(Pleenp).
In any case, your car is running so count your blessings. Back off of the boost and get it tuned. Dont take the i/c out.

POS7

^ So, you're saying it has to be more like a metallic ping. I was searching around the forum and found that some people don't actully hear the detonation at all, the car just starts stumbling and backfiring.

I don't plan to get the car tuned soon. There really aren't that many shops out here in hawaii. I only know of one that'll do the pfc decently. Its kind of strange that I was only running 10.5 lbs of boost when it happened, of course its what the commander recorded (and its supposed to be inaccurate).

I guess its either take the i/c out or stay off boost I'd rather deal with having to use the stock i/c over replacing a blown motor.

There's 61k on the motor (stock motor). I do frequent oil changes (every 2k) and the car hasnt been overheated or any thing to my knowledge

2FAST7S

I cant remember 100% but i do know it wasnt a normal pop more of a ping than anything. Most people dont hear it cause they either dont realize what to listen for or their cars are too loud. Even if they knew what to listen for by the time you back off its too late anyways so its pointless.
You really shouldnt be having issues. Still got a stock cat in there right? if so, you should be flowing ok for the pfc maps. I dont know how much more the pettit flows over stock but it sounds reasonable, just remove it!

dgeesaman

iTrader: (7)

I'm still not convinced we've established the difference between the sound of the apex seal shattering and blowing into the next chamber vs. the detonation itself. Naturally the knock sensor will register a high value - it's just a vibration sensor - so the shattering seal will be plenty to make a big reading.

Detonation can happen several times before the actually motor pop - and to me if your motor just goes boom once, will not be distinguishable from the busting seal. You'd need to have a case where there is some detonation followed by the pop of the seal.

Stumbling alone would seem to my very inexperienced senses to be an ignition breakup.

Dave

POS7

Yeah, I still got the stock cat in & that's what I figured as well.

I guess it could be ignition breakup or a misfire as well. I'll have to think about this one. Thanks for the suggestion guys.