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Discussion Starter · #1 ·
I'm the old 60's/70's Muscle Car dad who has been tasked with getting my son's car running and able to sell. My son is off to college and left his mess for me to deal with!!! Here is what he has:
2004 BMW 325i E46
2.5 Litre / Automatic Trans
Oriental Blue Metallic
  • Lowered – Raceland Coilovers
  • Stage 3 Tune /
RevMatch Motorsports
  • Spectre Intake/Filter
  • Long Tube Cat-Less Headers
He always had a backyard shade tree mechanic do his exhaust mods and by the looks of things, his little brother could've done better with a soldering gun!

Onto the good part: This car ran great for months and then just last week started running really bad after about 2 miles of driving. I thought he blew a head gasket, but after checking, all 6 hold at 170-180 P.S.I. I drove it and it ran great until about 2 miles then was very sluggish (barely making it home). I did a code scan and got upstream O2 sensor 1, upstream O2 sensor 2 & all cylinders misfire.

Being that the car is lowered, I struggled to get her up in the air and found some sort of plug/sensor just hanging under the front sub-frame. Not sure if this just happened or this has always been this way since he modded the exhaust. In any case, can someone tell me what this sensor is (see pictures)? He did have aftermarket headers installed and this is near the headers.

Thanks, and please be patient with an old man!!!

Finale...My first car was a 1970 Oldsmobile 442 W-30 with a 455 Super Rocket!!!! I'm old-skool!!!
 

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That's an O2 Sensor. It should be plugged into the exhaust manifold. There are two BEFORE the catalytic converter and two AFTER the catalytic converter. The DME (engine computer in BMW speak) can't accurately determine how the engine should run if it's not getting accurate data (or in this case, NO DATA) from an O2 Sensor. An UPSTREAM O2 Sensor error means BEFORE the Catalytic Converter.

On a standard EXHAUST Manifold, they are easily seen on the passenger side of the engine.
Motor vehicle Gas Automotive exterior Auto part Metal


 

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2005 330xi Auto, 2006 330ci Vert Auto
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1,820 Posts
As noted in an earlier response, from the factory there are 4 O2 sensors. 2 of them are before the catalytic converter and 2 after. Since your son's car has headers, then he had to have done something with the 4 O2 sensors. You showed 2 dangling O2 sensors. I cannot tell if they are pre-cat O2 sensors or post-cat O2 sensors. Is there anyway you can find all 4 O2 sensors somewhere?

Unresolved questions - you said the car ran great for months, so what changed? Do you know what the "tune" was supposed to do? I can guess that the "tune" eliminated the post-cat O2 sensors due to the headers. So what happened to the pre-cat O2 sensors? I do not think the BMW computer (DME) would operate very well without any O2 sensors.
 

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'02 330i 5-Speed
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Depending on where you live, no one is going to buy that car without cats since it won't pass emissions. Even cat-less headers should have bungs for the upstream O2 sensors. Can you find those? Should be up near the cylinder head.

I really hope your son isn't expecting a cut (or all???) of the proceeds from the sale since he dumped this in your lap.
 

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2002 330 Ci
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You might get a better deal selling it to an LKQ, if you have one nearby, than wasting time and money on it. Its only a 325i.... nothing really desirable.

I got $400 for an e53 shell.

Or... part it out and sell the bits on eBay, FB marketplace, etc
 

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Discussion Starter · #12 ·
Days later...

Both upstream sensors are in each bank. One downstream is in bank 1. Downstream bank 2 is laying on the skid plate - That port has been welded shut. The shade-tree mechanic/shitty welder did the work stated that the car will run fine with out cats & downstream sensors since they are juts there to make sure the cats are installed. It actually ran great like this for about 4 months - All of the sudden it started running like crap and purging.

Codes are showing bad upstream bank 1 & 2.

I'm debating selling it as is and disclosing what I know...Or, risk replacing both upstreams and seeing if it runs good again and selling it as a great running car.

My mind tells me since he has this tune thing, and he loves hammering it to hear the pops & see exhaust flames (all while always using Super 93 fuel), he fouled up the sensors.

Again...Gimme an old-skool big block and I can pull horses from anywhere! This new ECU controlled crap is for teh birds!!!
 

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2002 330 Ci
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3,036 Posts
LKQ won't buy vehicles without cats! So stupid, considering they'd well make their money off the motor, trans, interior & body parts!
Maybe depends on the area? Like I mentioned, I sold them a shell of an X5 for $400. You get less without cats and motor. That's here in TN. LKQ in other states probably vary.

However..... you can make more selling cats and engine on your own and selling the shell. I got $475 for m54 cats. Some place in TX. I can look it up if you need it.

$550 for the motor.....kid pulled it himself though. Made another $3k off various other bits.

Parting out is a pretty profitable return depending on circumstances.

Whichever way you go. Good luck. There's lots of info on this forum that can help you.
 

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Problem is we just moved into our new house 3 days ago. I have a broke down car sitting on jack-stands and look like total ******** to my neighbors! HOA does not allow this type of situation. My garage is packed with all my tools & hot rod - I am not moving my stuff outside to tear a car apart and piece sell!

There is a lot of info. on here - Thanks!
 

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Discussion Starter · #16 ·
We are in Bradenton. I bought two new upstream sensors, but just can't replace them with my health/disability issues. I'll sell car as-is for $2000! I just need it out of my driveway!!!
 

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We are in Bradenton. I bought two new upstream sensors, but just can't replace them with my health/disability issues. I'll sell car as-is for $2000! I just need it out of my driveway!!!
I'd jump on that lol but unfortunately I'm in Seattle.
Depending on the mileage, I'd say if you put that on your local fb marketplace for 2k it'll be gone in about 3 days.
Good luck!
 
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