wot noise. pro's advice wanted

[matt89]

when going wot, there seems to be a totally random tap noise every once and awhile, it's there at wot in 1st and 2nd gear, not as much in 3rd though. It's the same noise when just cruising then stabbing the gas above 2k rpms. it's an 01 ss. valve tapping would be there all the time, so I'm thinking detonation, but I had a close to 400whp eclipse and when it knocked, I couldn't hear it and the knock sensor would pick it up way before I could. Is this normal for this engine? anything I could check. Pcv valve is pretty clean and rattles when I shake it.

[0rion]

have you checked for an exhaust leak? Headers or stock exhaust? Have you logged it with anything to see if it's seeing knock?

[matt89]

It's bone stock with the exception of a knn air filter. I'm pretty familiar with exhaust leaks and this noise is too metalic and random to be that kind of noise. it comes from the front/left side of the engine. I don't know. I have a turbo kit in the mail coming for it but I don't want to put it on if the engine is knocking in STOCK tune! What else could it be? I haven't got anything to log with, but I have a predator tuning unit coming with the turbo kit that may help. So if it reads no knock, it's either a broken knock sensor or something else?

[SeVeReDiStOrTiOn]

Usually a knock sensor will throw a code if it isn't working...but they do rust out if water gets trapped under the intake manifold. Check the heat shields on the exhaust manifolds, sometimes they can come loose and make a metallic rattle sound...same goes for the metal ring for the o2 sensors insulation.

It could be some detonation like you said...you'll want to check your A/F ratio to make sure you're not too lean. The stock tunes are usually rich so if you're lean we can troubleshoot why later. The predator has a live data monitor feature but doesn't data log for the GM's...when I had my predator i usually had my g/f ride shotgun to write down the values for the 02's, LTFT ,KR, etc. You can't get a perfect a/f with the predator obviously but it'll get you out of the danger zone. At wot i usually shoot for 0% LTFT's and about 920mv for o2's.....part throttle about +2 to -2 LTFT's at around 60mph cruising. If you're still getting knock then pull some timing until you don't. You can also get custom tunes through diablosport....johan and mikel are cool dudes. Sorry if i'm telling you stuff you already know..

[matt89]

no that's cool man, I seemed to know about everything about the eclipse's 4g63 engine, but when it comes to the ls1, I'm pretty much starting from scratch! I do have a rattling 02 sensor, which I snapped off the 2 studs that hold the y pipe together. Any ideas for extracting the studs?! I have the bolts on the other side holding the y in place but now there is a nasty exhaust leak! ugghh. I have to drill the stud out don't I?

[0rion]

Might be a good time to just do headers and exhaust. I'm always looking for excuses for mods though .
What you're describing is really hard to diagnose over the intrawebnet. It's one of those things that easier to diagnose in person and even then it can be pretty tough. The predator will let you monitor real time but it won't record a log to review later so you have to let someone else drive and keep on eye on it. It's better than nothing though.

[matt89]

man, I thought that the programmer did logs! I just ordered the sts turbo kit with that and the guy I was dealing with said that I first had to download the stock tune then email it to him so that he could send me a tune at 5 lbs of boost... Hmmm there's something fishy about this. If it doesn't log, then I guess I'm on my own! I think I'll be alright as long as I keep an eye on the wide band though. I tuned my eclipse about every tank of gas because I was running on e85 fuel and it's different every where that you go. Once I had a nice fuel curve goin, I could just +/- fuel out at certian rpms to keep the afr's around 11 to 11.4. Is that where you want to keep the ls1's on boost too?

[SSpdDmon]

I'd Seafoam the motor, clean the MAF and replace the plugs. You might just have some carbon build up causing some pre-ignition.

[lightingrod]

one of the two belt tensioners (a/c one it has a bad problem of breaking)) could be smacking the stops of you have some mileage on the belts. seen this before drove me nuts till i found it.