I'm just looking for some thoughts on this before I drop it off at the shop. Regarding the vehicle in my sig; I'm having an issue where the car is louder than normal, some loss of power and annoying vibrations inside, but it comes and goes. Now, before you suggest exhaust, continue reading. I took it to a monro and a midas and neither could find an exhaust leak of any kind. There's no rhyme or reason to when it happens. It's present when driven cold, but sometimes subsides when driven long enough to warm up. However, it's sometimes fine when driven cold, but appears after warm up. Sometimes it's present all day, sometimes it's fine all day. Sometimes it's present while driving to the store, but when I come out of the store and start it up, it's fine. There's just no pattern at all.

 

That is not very helpful, could be a bunch of things. Timing, ignition, intake, clutch, exhaust, pulley system.

Some under hood investigation is in order.

 

Yea, I've been poking around under the hood (with my limited knowledge) and I've come up with nothing. I know I have limited info, but sometimes amazing things happen when you toss it out on the forum.

 

Is it throwing any codes?

 

Seeing that you have an Alta crank pulley I'd check to see if it is slipping on the crank or if it is broken.

Other than that, vibrations could be anything driveline from the flywheel to the wheels, and from intake to exhaust. As someone else asked; have you had any check engine lights come on?

 

No check engine lights at all, checked the crank pulley and belt and they look fine. The vibration disappears with the rest of the symptoms. It sometimes goes 3 -4 days without issues.

 

What is the common denominator here? Weather? Temp? Humidity? Sitting for a certain number of days? Being turned off and restarted shortly thereafter? Being driven hard? Highway miles at a constant speed?

I'm a firm believer that things like this are not really random. Something is causing this system to change the way it functions.

 

That's the problem, no common denominator whatsoever. If it's having the issue at 20mph, it's having it at 70mph. The problem was present two weeks ago at 25 degrees and it was there today at 63 degrees. Sometimes restarting it after shopping returns it to normal, sometimes it doesn't. It does it in the rain, snow and sunshine..........or it doesn't do it in the rain, snow and sunshine. Doesn't feel at all like a misfire. It's not spitting and sputtering. No hesitation. It get's loud like an exhaust leak with vibration and slight reduction in power. As far as the vibration, I don't mean the car is shaking, I just mean some of the interior plastic trim starts making noises. Now, I'm assuming here that midas and monroe were correct that no exhaust leak exists.

 

Start narrowing down small things. Where does it get loud from - engine, muffler, right below you? Does it get louder as you build revs? Any difference under load vs not under load? When it vibrates, I know you said the plastic squeaks... so it's not speed related? Does anything change throughout the rev range? Describe your loss in power? Does it just feel a little off or does it feel like you only have 75 hp? How long has this been going on? Have you done any maintenance recently? Do you have any electrical symptoms when this happens? Does your exhaust have a blue or white hue to it? All things that MAY help narrow your problem down.

 

It sounds more like it's close to the engine bay, maybe below me and it's constantly droning. If I take it out of gear and coast......silence. The vibration is most noticeable when in lower RPM's. The power loss isn't dramatic at all, probably wouldn't even be noticeable to anyone else. It's been about a month or so and I hadn't made any changes around the time it started. There aren't any electrical symptoms at all and I have no idea about blue or white hue.

 

Yeah, tons of information to be added. I have my first guess but I'll hold off until we hear more about this because I don't want to take a total shot in the dark.

 

Take the shot, I'm interested in hearing.

 

With the info you've given thus far, I'm gonna take a stab and say that I'd focus on the flywheel/clutch area.

Does this phenomenon tend to happen more in the higher gears?

 

It's loud through all the gears and at all speeds, from pulling out of the driveway to risking a speeding ticket on the highway. The vibration is most present at low RPM's. The clutch hasn't presented any problems and holds great, as it gets tested quite well daily.

 

You could easily have some intermittent issue with the spark, why not do the basics first:
1. Plugs
2. Plug Wires
3. Coil.

But IMHO Vibration and Noise that go away when taken out of gear, presuming it idles well, after ruling out exhaust leak of any sort, points pretty squarely at clutch and the harmonic damper.
But IIRC the Alta is NOT a damper, and while it does reduce reciprocating mass, its BAD for the engine from the standpoint of accelerated wear on crank and rod bearings. Hopefully your noise does not sound like rod knock, which is specifically what not having a damper leads to.
Only sticking my nose in your business cause you asked but I would launch that Alta, to the moon, and get an ATI Super Damper, or the PRW fluid damper.
Good Luck
Bruce

 

I'm thinking clutch/transmission area if you have ruled out the crank pulley/belt tensioner area.

You've checked the transmission oil?

 

Plugs, wires, coil are about 10k old and it just doesn't feel like that type of problem. It idles perfectly fine and I've never heard of a bad clutch making a car sound like it has an exhaust leak. As far as the Alta crank pulley, is there any documented instances of failure or engine damage related to it? I personally haven't been able to find any, mostly just opinions and theories.

 

The transmission shifts smooth as can be, no issues, however I will check the trans oil.

 

Can you record the sound so we can hear it? That would help significantly.

 

I actually tried before I started this thread, but it just didn't record well enough. It doesn't sound like a fart pipe, it's just a little louder than normal, exhaust leak type sound and it isn't loud enough for the recorder to pick it up.

 

Does it do it more when the car is under heavy load (i.e. starting up a hill, second gear, etc)?

 

Nope. It's either having the issue or it's not. When it's present it's all gears, slow or fast, up hill, down hill and everything in between. When it's not present it's good to go.

 

How's your fuel economy? Any change?

 

To help confirm exhaust leak, pick up some seafoam and run it through the vacuum lines. It'll cause a lot of smoke and, if there's a leak, help you spot any exhaust coming from where it shouldn't be.

 

Fuel usage seems the same. I don't exactly drive conservatively, so fuel economy is typically lacking.