fergymoto

OK back to work. I got the car up in the air today and have had it running in both neutral and drive with the rear wheels locked up to put slight load on the engine. It is definitely the exhaust system. It is 3" true duals with a X pipe, Moroso Spiral Flow muffs, and turndowns at the axle.

When the engine is loaded (ie in gear but car sitting still) the exhaust rattles fairly bad and it fades from present to worse in and out. The headers nor the exhaust system are making contact with ANYTHING. It just plain rattles on its own. I don't know what I can do short of going to a different exhaust setup.

Any of you have any ideas?

WS6T3RROR

Can go to diff exhaust or you could put rubber or urethane isolated hangers to damp the vibration. Make sure everything is tight and welded up. Other than that there should be no ratting unless something is touching. Steel pipes do not just rattle on thier own, its resonating off of something.

Are you absolutely sure theres nothing under the car that could be loose or rattling?

Motor mounts?

Ac lines banging off the hood?

fergymoto

The exhaust has a rubber hanger on each side at the rear. Other than that the front is just bolted to the collectors. Car has poly engine and trans mounts and all are tight. The AC lines clear the hood by a mile. The hood is the stock fiberglass hood and has no rub marks or anything.

The exhaust is not touching anything that I can see. I know it isn't usual for pipes to just rattle but that seems to be the case. Could it be the header primaries rattling against each other at the collector? The sound seems to be coming from the left side or the X pipe itself, but I am having a hard time telling with how loud the car is.

WS6T3RROR

In certain rare cases just the extreme volume of the exhaust is enough to freak out the knock sensor.

Other than what I have posted before i'm all outa ideas.

fergymoto

It's definitely the rattling. I just can't figure out why it's rattling yet. I really don't want to change to another exhaust setup right now.

fergymoto

I can bang the exhaust with my hand and it rattles. It's coming from the inside in the drivers side/x pipe area. I have no idea what to do about it short of getting another exhaust and I really don't want to do that right now.

WS6T3RROR

Take it off and see why its rattling dan. Maybe somebody left you some spare nuts and bolts in there. Or it could be from the last time you fragged your engine and some part of it is still stuck in there .

fergymoto

Haha about that. I haven't had a chance to post yet but I took it off this morning. It is in fact not my true duals rattling. After I took it off I bumped my headers on each side with my hands. No noise on the passenger side. Go over to the drivers side, bump it, rattles like hell. I suspect the slip fit #1 primary. I take it off, no more rattle. So I enlarged the primary a bit and now it fits tighter and does not rattle anymore by hand. I haven't put it back together and fired it up yet because I wanted to do some stuff with my exhaust while it is off. I should have to back together tomorrow and I'll let you know if it solves my problem. It should.

WS6T3RROR

Put some of the copper rtv on the slip fit before you cram it in there, it will help somewhat to damp the vibrations if its still not tight enough. You can also use one of those exhaust U clamps just to squeeze the pipe down a little (dont go all he-man on it) then take the clamp off and it should be VERY tight after that.

fergymoto

Well, after fixing that the rattle is gone. Knock retard is not...

WS6T3RROR

What does the knock look like the way it sits right now? Only wot Only part throttle etc?

fergymoto

Looks like *****. The whole time. Here's a log lol

pass1.uni

I am starting to get frustrated here.

WS6T3RROR

Looks disgusting to me. Also looks like false knock. Did you reset your computer after you fixed the header issue. The computer tends to learn where it has detected knock before and will start to pull some out all the time. Look at your knock counts all through the run, doesnt really pick up any actual knock or any reason in particular to retard timing at least during the log as far as I can tell.

Just pull the pcm batt fuse in the side of the dash for a bit so it will start relearning again.

dookie454

Yea, I agree with Warrior...

You are only getting actual Knock Counts at a few spots, your not getting any knock during WOT, but you have to figure out why the Constant Knock Retard is pulling timing.. looks like settings are messed up.. it's not due to knock detection it's due to maybe the settings being too sensitive? YOu can reduce that.

You do show actual Knock Counts on Decel with no Injector Pulse, starting at Rec# 373 that means no real spark knock is occuring but your knock sensor is picking something up that sounds like knock.. likely a rattle from something external or a rod, lifter, piston, etc.

Put a cheap-o $20 chambered+Baffled muffler on there and see what you hear.

Also, you can actually splice your knock sensor signal wire to a tape recorder mic-input and record your motor noise... see if there's a knocking pattern or a rattle pattern to it... knock sensors are just microphones... works good!

dookie454

I looked at all your logs.. knock is all at random... most all have random Knock Counts during Decel also, when there is no ingition occurring that means either the knock sensor/wiring/system is messed up or you have a rattle setting it off. I would start by reducing your "Bad Gas" Knock retard settings drasticlly since that should make the "carry over" knock retard go away for now.. then look for bad wires or bad sensor... I would still put a tape recorder on the knock sensor to see if you can hear what's happening.

Then (or maybe first), I would actually disconnect the knock sensor completely and drive around normal and see what happens. Just be sure to support the wire right next to the sensor incase the wire is shorting on something maybe you can get it to happen without it even connected.

Maybe it's time for a new knock sensor? Might be worth it just to cross it off the list.

There are times when you might see real knock, like when you slammed the pedal from 2% to 100% in under 1/10th of a second, looks like it picked up a little from that but the rest looks random.