I need someone expierianced with LS1's to check out my car please read!!!

[rgaynor85]

ok I have posted on ls1tech with this issue and noone really gave me a awnser but i now have more info on my problem and im also more worried. ok before i was having the issue where in 3rd+ gears if i was low in the rpms like 1500rpm and i would tap the gas sorta i would get this rattle/clinking noise under the hood/front of car area. couldnt figure it out or why i would have this noise, so today for the first time sense its been so cold i had my t's off and took it out on lunch break for a joy ride on some long open roads. well as soon as i go to pull the car hard once i got above around 4500rpm rattle rattle clinky clinky that noise is there. never noticed it in high rpms, that and i dont usually open my car up much so i never knew i had the noise in high rpms as well. so know im trying to figure our whats wrong, detantation perhaps, i run 93octane and my last tank of gas i threw in octane booster just to try and see if it would help. could my injectors or fuel filter be cloged and causeing me not to get enough fuel but then why would it make the nosie at low low cruiseing rpms, i dunno maybe its not internal but i got no idea what could make noise like that outside, please someone gimme an idea to go on or if someone here in jersey, im in woodbridge, could help out a local f-body buddy hehe shoot me a reply

[foff667]

if you feel like taking a drive down to trenton I could at least scan your car to see if anything odd pops up while your driving IE KR or what have you. let me know.

lata
Bill

[rgaynor85]

IE KR??? but maybe what u got autotap or sumthin

edit::
duh should have looked at sig.. hehe hp tuners huh so will i get charged to check my car out

[foff667]

nope just bring it down I'll take a look at it for ya

[rgaynor85]

ok what time would i be able to bring it down during the week till and on weekends.

[foff667]

Preferrably 5-8pm at night but just let me know roughly what time you'll be coming so I can schedule my dinner around when you'll be here

[rgaynor85]

ok well i get home from work around 6:15 so itll prolly be a 45 min ride for me so id guess like 7:30 to be safe ill figure out a day this week maybe, any day prefered im 20 so im free everynight so it doesnt matter to me lemme know what u prefer id come tonite if u wanted hehe sense its nice out

[enRo]

I dunno, out of curiosity, have you had exhaust work done to your car? I kinda had the same problem when I first got my exhaust put on. GM didnt give enough room with a bar where the Y-pipe meets the mid-pipe, and my car would only rattle under low RPMS with a tap of the gas. So what we did was throw in a shimmy under the bolts of this bar and problem was solved. [/2 cents]

[rgaynor85]

umm i bought the car with a flowmaster catback but nothing i know of other than that ive only owned the car for about 1 month but did u get the same noise when u romped on it to, but thanks ill look at that

[enRo]

Originally Posted by rgaynor85

umm i bought the car with a flowmaster catback but nothing i know of other than that ive only owned the car for about 1 month but did u get the same noise when u romped on it to, but thanks ill look at that

Yep, never a noise mid range, only around 5000+ RPMS and below 1800 RPMS. Take a look under the middle of the car and see how much room u have between the y-pipe/midpipe merge and the small bar. When mine was put on, there was only a 1/4 inch of room... theres about 1 inch of space now, and I never had the noise since.

[rgaynor85]

wow thats sounding like my problem hmm just by the rpms u had the issue in id almost guess maybe thats it, hmm

[foff667]

your talking about the underbrace right? Didn't you feel that though?

[enRo]

Originally Posted by foff667

your talking about the underbrace right? Didn't you feel that though?

I didnt feel it on mine. What I was thinking, cuz the exhaust was getting louder by the mile when i first got it installed, the low rpms and the drone just rattled the exhaust against the underbrace ... but the high RPMS was just the same too ... i didnt feel it at all, it was like every time the exhaust was vibrating, it would tap against the brace. It was just a real annoying tapping.

[foff667]

we'll take a look when he brings it over tonight thanks for the heads up

maybe !tunnelbrace mod lol

[rgaynor85]

whats the tunnel brace mod

[foff667]

theres a thin piece of sheetmetal that braces the underchassis on 4th gens...held in by 4 bolts...delete it lol if thats your noise that will get rid of it...or as he said you could put some washers in there to give it slightly more room possibly.

[rgaynor85]

but wouldnt that make you have less chassis stability witch is why we need sub frame connectors so badly

[foff667]

if youve ever seen this thing i doubt its doing much...many people have taken it off...personally i just replaced mine with a $50 Driveshaft loop.

[rgaynor85]

ill prolly just shim it if thats it

[Mike]

ive run without it for a year, bills right its useless.......

and you should also check your trans mount to see if the busshing is broke...that could be causing some rattling as you wind the motor out

[rgaynor85]

well me and bill scanned my car and i think from what he said im gettin some what it sounds tobe detanation and abnormal knock retard or sumthin the exhaust seemed stright no clunking there and the trans mount looked ok to
im gonna do a full tune up and see what happens but if anyone else has some ideas or think they could figure it out lemme know

[foff667]

yeah it was odd...it definitly sounded like some mild audible knock once he hit like 4500 rpms...could see 0-5* of KR in the scanner at those points...also had up to 15* of KR when toying around with the clutch a bit...not sure what to think about it...I'll try and post the excel files for all to view, but i dont know what to make of it or why its happening...its a completely stock tune(checked it against another stocker to make sure) so its just odd.

[V]

i had a flowmaster catback and it hit the brace. i shimmed it with a few washers. after i ripped my tq arm, i replaced it with the adjustable spohn one that replaces the brace and mounts the tq arm off there. since then no problems with clearence. My magnaflow now fit great, but i only drove it 2 miles before the motor blew.

[foff667]

its definly not a brace issue fwiw guys, nor is it a bad tranny mount.

[ElChiefWS6]

A possible cheap fix is to run some GM top end cleaner through. If you have carbon build up that could cause detonation and then the knock retard. Correct me if I'm wrong.