Detonation? - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

opponheimer · 05-05-2008, 11:22 AM

So about a month ago I let a friend of mine drive my s14 (s13 sr20det w/ gt2871r w/ 740cc w/ bpu) while I sat in the passenger's seat. The car is on 20lbs of boost and runs 93 Octane all the time with enthalpy rom tune. AFR at WOT is 11.3-11.5:1 always. UP around 4500rpm - 5500rpm in 4rth gear in WOT we could hear a quiet little noise that resembled bb's hitting a metal shield or something, it sounded like detonation. After 5500rpm it would stop.

Timing is 15 deg.

Anyways, I lowered the boost dramatically to 15lbs and I still hear it. Could it in fact be something else?

My Knock sensor is in good working order and ecu throws no codes, so if it was knock, wouldn't the car have retarded timing if it really was knock that was loud enough to be heard by human ear? The car runs flawlessly regardless.

I am almost wanting to make want of those home testers you bolt to your block with headphones and tubing. Anyone have any advice on where to look, or absolutely know what this is, than let me know. Thanks!

just1pepsi · 05-05-2008, 11:25 AM

Could have been i guess.. may not have been bad enough for the KS to retard anything. (bad gas possibly) May be a good idea to check for any air leaks on the intake side of things.. and the exhaust for that matter.. sometimes exhaust leaks make a noise sort of like you describe.. they can be more of a ticking, but thats not set in stone.

opponheimer · 05-05-2008, 11:28 AM

thats not a bad idea to check for exhaust leaks, i know exhaust leaks can cause crazy noises. good suggestion, edit, I felt around for leaks didn't find any

steve shadows · 05-05-2008, 12:15 PM

Does he have an electronic Boost Controller?

With a solenoid valve?

Click Click Click goes the valve...just a thought

posdrift240 · 05-05-2008, 12:20 PM

how much boost are those solenoid valves good for? I have one also.

steve shadows · 05-05-2008, 04:39 PM

I don't know, ive used avcrs north of 30 psi.

opponheimer · 05-05-2008, 08:58 PM

This is my car we're talking about and no I have an adjustable actuator rod. Its not the machine gun solenoid noise.. Any quick way i can check its detonation 4 sure?

Z U L8R · 05-06-2008, 01:57 PM

with a boroscope, you can look inside your cylinder through your spark plug hole hehe

you might wanna stay at 14psi on pump and put some race gas in there when you're gonna run 20psi. my .02

Dave =]

05-05-2008, 11:22 AM	#1
opponheimer Zilvia FREAK! Join Date: Apr 2007 Location: Bikini Atoll Posts: 1,267 Trader Rating: (3) Feedback Score: 3 reviews	Detonation? So about a month ago I let a friend of mine drive my s14 (s13 sr20det w/ gt2871r w/ 740cc w/ bpu) while I sat in the passenger's seat. The car is on 20lbs of boost and runs 93 Octane all the time with enthalpy rom tune. AFR at WOT is 11.3-11.5:1 always. UP around 4500rpm - 5500rpm in 4rth gear in WOT we could hear a quiet little noise that resembled bb's hitting a metal shield or something, it sounded like detonation. After 5500rpm it would stop. Timing is 15 deg. Anyways, I lowered the boost dramatically to 15lbs and I still hear it. Could it in fact be something else? My Knock sensor is in good working order and ecu throws no codes, so if it was knock, wouldn't the car have retarded timing if it really was knock that was loud enough to be heard by human ear? The car runs flawlessly regardless. I am almost wanting to make want of those home testers you bolt to your block with headphones and tubing. Anyone have any advice on where to look, or absolutely know what this is, than let me know. Thanks!

05-05-2008, 12:15 PM	#4
steve shadows Post Whore! Join Date: Aug 2003 Location: LA and OC Posts: 8,202 Trader Rating: (5) Feedback Score: 5 reviews	Does he have an electronic Boost Controller? With a solenoid valve? Click Click Click goes the valve...just a thought __________________ Like Me on FaceBook !

05-05-2008, 12:20 PM	#5
posdrift240 Zilvia Member Join Date: Oct 2007 Location: Rhea Posts: 207 Trader Rating: (0) Feedback Score: 0 reviews	how much boost are those solenoid valves good for? I have one also. __________________

05-05-2008, 04:39 PM	#6
steve shadows Post Whore! Join Date: Aug 2003 Location: LA and OC Posts: 8,202 Trader Rating: (5) Feedback Score: 5 reviews	I don't know, ive used avcrs north of 30 psi. __________________ Like Me on FaceBook !

05-06-2008, 01:57 PM	#8
Z U L8R Zilvia FREAK! Join Date: Jan 2007 Location: Georgia Age: 43 Posts: 1,194 Trader Rating: (0) Feedback Score: 0 reviews	with a boroscope, you can look inside your cylinder through your spark plug hole hehe you might wanna stay at 14psi on pump and put some race gas in there when you're gonna run 20psi. my .02 Dave =] __________________ RB25 280z GT30/76R 441hp/381tq 11.9@125

05-05-2008, 11:25 AM	#2
just1pepsi Zilvia Addict Join Date: Dec 2003 Location: OKC Age: 42 Posts: 657 Trader Rating: (0) Feedback Score: 0 reviews	Could have been i guess.. may not have been bad enough for the KS to retard anything. (bad gas possibly) May be a good idea to check for any air leaks on the intake side of things.. and the exhaust for that matter.. sometimes exhaust leaks make a noise sort of like you describe.. they can be more of a ticking, but thats not set in stone.

05-05-2008, 11:28 AM	#3
opponheimer Zilvia FREAK! Join Date: Apr 2007 Location: Bikini Atoll Posts: 1,267 Trader Rating: (3) Feedback Score: 3 reviews	thats not a bad idea to check for exhaust leaks, i know exhaust leaks can cause crazy noises. good suggestion, edit, I felt around for leaks didn't find any

05-05-2008, 08:58 PM	#7
opponheimer Zilvia FREAK! Join Date: Apr 2007 Location: Bikini Atoll Posts: 1,267 Trader Rating: (3) Feedback Score: 3 reviews	This is my car we're talking about and no I have an adjustable actuator rod. Its not the machine gun solenoid noise.. Any quick way i can check its detonation 4 sure?