Sour exhaust

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87e30
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Sour exhaust

Postby 87e30 » Wed Jan 06, 2016 2:17 pm

So my blue 325e has had a weird problem a few times. All of a sudden the brake lining light will come on very dim, engine loses power, and exhaust smells very sour. Sometimes turning the car off and right back on will clear everything, other times it goes away on its own after a minute or two. Any clue? I'm stumped.
Schwarz 5-speed 87 325is (newest project)
Arktisblau 5-speed 86 325e (current DD)
Schwarz 5-speed 87 325e (parts car/LS1 swap?)
Gazellenbeige automatic 85 318i (70,000 miles)
Alpine white 5-speed 87 325is (my first e30, possibly for sale)
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Re: Sour exhaust

Postby Yoshi » Wed Jan 06, 2016 3:34 pm

sour? weird... engine ground? That's always my go to lol.
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Re: Sour exhaust

Postby 87e30 » Thu Jan 07, 2016 12:26 am

Is the engine ground in any way connected to the brake lining light? I will definitely check the grounds and tighten them up as needed. I also have to check the wires going to the starter. There's a small black wire that turns things on and off when I wiggle it. I'm thinking that might have something to do with the intermittent starter problem I've been having since I got the car. Weird thing though, if I'm having a problem with the starter not working, and I turn the engine by hand, it will usually start right up.

So could a weak ground cause the exhaust to smell sour? I couldn't imagine why that would be. I could see it possibly causing the other symptoms.
Schwarz 5-speed 87 325is (newest project)
Arktisblau 5-speed 86 325e (current DD)
Schwarz 5-speed 87 325e (parts car/LS1 swap?)
Gazellenbeige automatic 85 318i (70,000 miles)
Alpine white 5-speed 87 325is (my first e30, possibly for sale)
99 Suburban
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Re: Sour exhaust

Postby Yoshi » Thu Jan 07, 2016 12:15 pm

The brake lining light coming on is a sign of low voltage in the system. Same with the starter not working. The sour smell could simply be from incomplete combustion and running lean. Lean conditions do smell odd. I wouldn't say sour but I could see how someone would describe it as sour.

Maybe your coil is going. I'm not entirely sure.
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Re: Sour exhaust

Postby M20_fever » Thu Jan 07, 2016 2:42 pm

That wire disables accessories while cranking to reduce load on the system. It will definitely cause issues if it's loose, but shouldn't effect the brake lining light. Maybe the voltage regulator in the alternator is going. Does it usually come on at idle/low RPM?

When you say the exhaust smells sour, does it smell like rotten eggs? Sounds like the cat is going bad. They will start to disintegrate internally and clog, which would cause the engine to bog and run like crap.
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Re: Sour exhaust

Postby 87e30 » Thu Jan 07, 2016 5:47 pm

I'm pretty sure my alternator is working properly. I DID have to replace my battery on Monday, but it was colder than balls over the weekend (less than 10 degrees F on average) and the battery was about done anyway. It had sat for at least 2.5 years dead. I'm surprised it held a charge at all. I knew what the wire was for, but my white car never used one. Would that cause the starter to not do anything at all when I turn the key? No click, no spin, no nada nuttin.

No, I don't mean rotten eggs, I mean sour. Can't really describe it, but maybe imagine a bum who hasn't showered in 8 years eating some spoiled veal. I'm just guessing on that, but I can't think of a better way to describe it.

I know if the cat is clogged it could cause the engine to run like crap. I don't think that's it though. Also if that was the problem, why would I have the dimly lit brake lining light ONLY when it's running like crap and smelling weird? Sometimes I can shut it off while moving, leave it off for a few seconds, turn the key back on, pop the clutch, and it's running like a brand new car. Sometimes everything goes back to normal after a few seconds to a minute.

I've only had this problem less than a dozen times after putting several thousand miles on teh car. I would think if the cat had anything to do with it the problem would show up almost constantly.
Schwarz 5-speed 87 325is (newest project)
Arktisblau 5-speed 86 325e (current DD)
Schwarz 5-speed 87 325e (parts car/LS1 swap?)
Gazellenbeige automatic 85 318i (70,000 miles)
Alpine white 5-speed 87 325is (my first e30, possibly for sale)
99 Suburban
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Re: Sour exhaust

Postby Yoshi » Thu Jan 07, 2016 7:42 pm

Yea I'm going with something electrical not playing nice.
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Re: Sour exhaust

Postby M20_fever » Thu Jan 07, 2016 8:33 pm

clogged cat can be intermittent, happened on my old 240DL. Would run great, then bog like crazy until I shut it off, restart and it would be fine for a while. Maybe when the cat clogs it drops RPM too much and alt isn't putting out enough juice. TBH sounds like more than one issue going on here.
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Re: Sour exhaust

Postby 87e30 » Fri Jan 08, 2016 1:15 am

I know the smell of a clogged cat, and this is definitely not it, but maybe it's time to hollow the cat out anyway. Other than being illegal, is there any reason NOT to hollow it out? I know there's a guy selling a used OEM e30 cat on CL right now in my area. Yes, I know it's also illegal to sell a used cat. He wants like $800 or some shit for it anyway. I wouldn't even consider that.

Gotta find me a volt meter and somewhere to mount it in the car so I can see if it drops when things are acting up. When my alternator belt broke it was the battery light that came on, not the brake lining light. It's not like the RPMs are dropping that much anyway. I just can't get it over around 2500 RPM when that light is on.
Schwarz 5-speed 87 325is (newest project)
Arktisblau 5-speed 86 325e (current DD)
Schwarz 5-speed 87 325e (parts car/LS1 swap?)
Gazellenbeige automatic 85 318i (70,000 miles)
Alpine white 5-speed 87 325is (my first e30, possibly for sale)
99 Suburban
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Re: Sour exhaust

Postby Yoshi » Fri Jan 08, 2016 12:11 pm

It's illegal to sell cats? I never knew.
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Re: Sour exhaust

Postby 87e30 » Fri Jan 08, 2016 1:18 pm

Yoshi wrote:It's illegal to sell cats? I never knew.


Have you never been to a junk yard? There's a reason why you will never find one on a car there.
Schwarz 5-speed 87 325is (newest project)
Arktisblau 5-speed 86 325e (current DD)
Schwarz 5-speed 87 325e (parts car/LS1 swap?)
Gazellenbeige automatic 85 318i (70,000 miles)
Alpine white 5-speed 87 325is (my first e30, possibly for sale)
99 Suburban
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Re: Sour exhaust

Postby M20_fever » Fri Jan 08, 2016 2:38 pm

I always thought it was because they are worth so much in scrap they just recycle them. Guess it makes sense, reduces the people crawling under cars with a sawsall stealing cats. Happens quite a bit in Milwaukee and Chicago.

monitoring volts is probably the best next step, along with checking/cleaning engine and chassis grounds.
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Re: Sour exhaust

Postby 87e30 » Fri Jan 08, 2016 11:32 pm

Oh it doesn't cut down on people stealing them at all. If anything it makes them MORE frequently stolen. My boss had a friend with a dealership down the highway from us who got hit at least 5 times. They came in over night and cut out between 10 and 40 cats at a time. Recycling them gets from $50 to $300 each if they are OEM. Aftermarket cats most recyclers don't even want. Some of the scrap yards around here will actually CHARGE YOU up to $150 if there is an aftermarket cat on a car you bring in!
Schwarz 5-speed 87 325is (newest project)
Arktisblau 5-speed 86 325e (current DD)
Schwarz 5-speed 87 325e (parts car/LS1 swap?)
Gazellenbeige automatic 85 318i (70,000 miles)
Alpine white 5-speed 87 325is (my first e30, possibly for sale)
99 Suburban
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Re: Sour exhaust

Postby Clifford.brown » Fri Jan 15, 2016 1:06 am

Check your coil , I have had them go bad .when they get hot the resistance increases and they drop voltage like crazy causing all sorts of issues. Also could be distributer causing timing issues which can add to lack of rpm and fuel loading
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Re: Sour exhaust

Postby Clifford.brown » Fri Jan 15, 2016 1:09 am

I forgot , if your distributor is not advancing your timing it will lack rpm and power

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