Detonation question

[WhippleCharged Sonic]

Will signs of detonation show on the plugs and be very noticable? I am batteling this rattle I have up front that I cannot find and am beginning to wonder if it is detonation. The kicker is the rattle is audible on acceleration, but is the loudest after I get on it then let off the gas and as the engine deccelerates you can hear this rattle. If you sit inside the cabin and rev the engine in neutral you can hear it a little, but you cannot hear it outside the car if you rev it at the throttle body. I cannot find out where it is coming from. I thought it may be the transmission. Now I am wondering if it is detonation, but when I dynoed my car with the chip and pulley the A/F was good. I am going to pull the plugs today to check them to see if anything is going on there. :shrug:

 

[WhippleCharged Sonic]

Anyone?

 

[Forbidden Snake]

Talk to a guy by the name of jguererro. I helped him install his 2.9" pulley, chip, and NGK-TR6 plugs. We took the car for a test run right after the install and he had the exact same problem you are describing. He got his chip reburned, not by the same vendor who sold it to him though, and I believe it's running much better.

Also you may want to try a different gas brand. That may help as well. As far as your original question goes, if you look at the plugs and it's melted or deformed from new, then it could very well be detonation. If it looks good then I really have no idea. Good luck..

 

[WhippleCharged Sonic]

There are a few other things I am going to try out. I never tried getting on it and then pushing the clutch in on deceleration. That would rule out the clutch. I was also reading that o2 sensors coming loose. That is very possible because I dynoed the end of July (they installed the o2 bung for the A/F) then installed my chip, pulley and plugs a month later. Then the car sat for a month...so I guess it is possible that the o2 sensor came loose in a months time of driving it including track runs and another dyno which they used the tailpipe bung for that. My A/F was very good by the way...which is why I am almost positive it is not detonation.

 

[Forbidden Snake]

It may be a possibility that your 02 sensors came loose, but I highly doubt that. Even if it did, it wouldn't be loud enough for you to hear them. At least that's what I think.

Your A/F may be good, but the chip may advanced your timing too much to still causing detonation. Or you just got a bad batch of gas.

Try taking out the chip and making a couple of not-too-hard runs. See if that makes a difference. Your ECU should be smart enough to compensate for fuel so don't worry about blowing it up. There are guys on here running pullied cobras for months without a chip with no issues.

Good luck.

 

[broke7]

If the detoantion was that loud and is that audible I believe it would tear something up or make plugs look bad, does the car feel good up top or stumble when this noise happens. If the car is that lean you should be able to see it with 02 sensor values on a scanner as well, they will dip violently into low .8 and .7 range. good WOT voltage is in .90v-.94v area.

Have you had it on the dyno yet? If its on the dyno and car makes this noise and the curve drops down for no reason when this noise is happening, I would say its detonation then.

My car makes a rattle in the midrange at part throttle, and Ive went threw everything and I cant find mine.

 

[WhippleCharged Sonic]

Didn't get the chance to take a look at it today. The car is strong as hell right now. Took it to the track last Saturday and ran mid to high 12's at around 116 mph. I honestly don't think it is detonation. The rattle does not show its ugly face until I decelerate from relatively high RPM's. If I get a chance this weekend I will put it up on ramps to check the o2 sensors and anything else that may cause the rattle. I will also check the plugs just to see. Who knows...

 

[broke7]

also check your pipes in the back rubbing on the ballast on the bottom of the rear end, sounds like exhaust or something is moving around or rubbing on a frampiece

 

[six speed]

Detonation will most likely happen under a big load in a high gear. It's the chamber getting to hot. Your plugs will show some signs of det if it is bad I have seen cars with the end of the plug gone. Cooled plugs,cooler motor water temp,more fuel,less timing and better fuel, this should help det or it did on my old car good luck. Yes, I have blown a few motors because detonation.

 

[doubleblack]

Originally posted by BDC_CBRA02
The kicker is the rattle is audible on acceleration, but is the loudest after I get on it then let off the gas and as the engine deccelerates you can hear this rattle. If you sit inside the cabin and rev the engine in neutral you can hear it a little, but you cannot hear it outside the car if you rev it at the throttle body.

"Louder on decceleration", I really doubt it's detonation. Detonation usually happens under a load when the motor is accelerating. "Detonating and reving in nuetral", I'm not sure it can happen...maybe, if your tune is WAY THE HELL OFF...it really does sound like something is loose. It's hard to describe but pinging sounds like slight crackling and popping, kinda like there's alot of static electricity going on under the hood.

BTW, YOU CAN STILL DETONATE W/ GOOD AIR FUEL RATIOS...
-timing too advanced
-octane too low
-spark plugs heat range too hot

 

[dougwg]

It's not detonation! ...

I rode in the car....

but still not sure what it is but it's not detonation!

 

[WhippleCharged Sonic]

Originally posted by dougwg
It's not detonation! ...

I rode in the car....

but still not sure what it is but it's not detonation!

Damn Doug. I am just trying to go through all the possibilities here dude. I just pulled all the driver side plugs and they look identical to the stock ones when I pulled them. I am posting pics in a few minutes here.

 

[dougwg]

this IS strange....

have you had a chance to let your father-in-law take a listen to it yet?

*edit* father-in-law

 

[dougwg]

"all the possibilities ".... understood...

did you contact Postban or cobra03 yet to listen to their cars?...

I think this would be an easy way to get some info...

fugin cobras are weird:shrug:

 

[WhippleCharged Sonic]

No I have not. I listened to T-Bones car and his blower sounds pretty much identical. I have not talked to my father-in-law yet. Here are the pics of the plugs. Look just like the stockers when I took them out a month ago.

These are drivers side plugs

This is one of the plugs up close...they all look like this.

Should I pull the passenger side plugs to check them as well??? What do you think...they look fine to me.

 

[dougwg]

maybe it's just blower noise.... (gears and the rotor pack) ? :shrug:

 

[WhippleCharged Sonic]

I think I found it fellas!!!! I put er up on ramps and squeezed my fat a$$ underneath to see that the front o2 sensors were WAY LOOSE...both of them! I don't have the size wrench I need to tighten them up real good, but I used a pair of locking channel locks to tighten them up enough to buy me some time to get the right wrench. I have not been able to test drive yet, but I am almost positive this is the fix!!!!!

 

[dougwg]

:beer: :thumbsup:

fugin o2's:bash: :bash:

 

[dougwg]

they make ramps big enough for you to get under there? hehe

 

[WhippleCharged Sonic]

Originally posted by dougwg
they make ramps big enough for you to get under there? hehe

Hey Doug...FA-Q...sound it out! :-D

It was the fix by the way. Just took it out and the rattle is gone. That ticking noise has also quieted down a bit too. With those o2's being so loose that is where the exhaust leak sound was coming from I think. Now I have to send my chip back to Rick to add a second program and a switch so I can run either pulley and I will be a happy camper!!!!! :beer: