Rattle, Rough Idle, and Gas Consumption...WTF??

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drumsbeloud

Member
:
02 MP5-T
Ok, I'm hoping someone can help me diagnose this problem....


In the past week or so, I've developed a high-pitched metallic rattling sound that I hear only around 2500 rpm. The sound is present both when the car is in gear and when it is in neutral and the sound is consistent (i.e., it is not intermittent).

This rattling noise may or may not have anything to do with the rest of my problems, but something is wrong regardless. Anyhoo...I have also noticed lately that I have been getting very poor gas mileage and I seem to smell unburned gas more often than normal. In addition, just today I noticed that my idle is a little rough. On my 25 minute drive home from work today the revs 'dipped' while at idle (almost stalling) 3 times.

I have checked for obvious leaks and checked the accessible hose connections and nothing seems to be loose or cracked.

Does ANYONE know what might be wrong? I figure I'm going to take it to my mechanic tomorrow to see what he thinks, but I'd like to get some thoughts here first.

Any help is appreciated!
 
drumsbeloud said:
Ok, I'm hoping someone can help me diagnose this problem....


In the past week or so, I've developed a high-pitched metallic rattling sound that I hear only around 2500 rpm. The sound is present both when the car is in gear and when it is in neutral and the sound is consistent (i.e., it is not intermittent).

This rattling noise may or may not have anything to do with the rest of my problems, but something is wrong regardless. Anyhoo...I have also noticed lately that I have been getting very poor gas mileage and I seem to smell unburned gas more often than normal. In addition, just today I noticed that my idle is a little rough. On my 25 minute drive home from work today the revs 'dipped' while at idle (almost stalling) 3 times.

I have checked for obvious leaks and checked the accessible hose connections and nothing seems to be loose or cracked.

Does ANYONE know what might be wrong? I figure I'm going to take it to my mechanic tomorrow to see what he thinks, but I'd like to get some thoughts here first.

Any help is appreciated!
Click to expand...

Is there any smoke coming out the tail pipe? I see you turboed the car...Is that the stock motor? Are you losing power? Sorry, but it can be almost anything...Something simple as a loose bolt, or even worse spun bearings.
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Oooooor...It can be your egr :)

Sorry, had to say that...It seems to be the usual answer around here when people have problems with their car!

Have it checked and let us know.

WiL
 
turbo and stock motor, yes....but there's no smoke (nor has there ever been) and all the power's still there.

it might be the egr...i know that would cause the idle, but i'm not sure about the other issues...i'll look into it.
 
I have always seen it described in similar terms. Also, have you pulled your plugs and looked at them?
 
the rattle sounds like a heat sheild that is loose/hitting

check vacuum lines for leaks, and if thats not it check plugs and compression test it
 
I looked into it last night and it turns out a couple exhaust flange bolts were loose. That explains the gas smell and the rattle. I'm going to clean the EGR today and see if that helps the mileage and idle issue.
 
Well, I cleaned the EGR today and I gotta say, this is a VERY good thing to do. Like others have said, the car runs SO much more smoothly now. It really feels like a brand new car.

I just filled up with 94 (at $1.289/L (CDN) ...or $4.43/gal (USD)) so we'll see how the gas mileage is now.
 
drumsbeloud said:
Well, I cleaned the EGR today and I gotta say, this is a VERY good thing to do. Like others have said, the car runs SO much more smoothly now. It really feels like a brand new car.

I just filled up with 94 (at $1.289/L (CDN) ...or $4.43/gal (USD)) so we'll see how the gas mileage is now.
Click to expand...

How many miles are you at on the car? I may need to try this if it really improves idle that much. Was it loaded with crud?
 
Around 87,000 kms (or 54,000 miles). There was a lot of carbon build-up, but to be honest I was expecting more. It's not so much the idle that's better, but just the 'smoothness' of the car. Driving in first and second is much better, with less hesitation and 'jerking'. It was a bit of a pain in the ass to get the EGR off and back on...but it wasn't TOO bad. If you have giant hands, it might be tricky though.
 
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