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Discussion Starter #1 (Edited)
EDIT: Photos added

I've already made one post about this car, and despite views, I'm not getting any replies, so I'm gunna make a new one, and try to word it better.

I've got a 99 Mk3 Jetta wolfsburg edition 2.0L 5 speed

Its throwing 4 codes

MAF sensor out of range - too rich
Camshaft sensor irratic/out of range - too rich
O2 sensor - too rich
Evap. canister - check purge valve

Symptoms:
Slightly hard to crank.
Drives fine until warm, then starts rapidly loosing power
for example after I've driven 5 miles, and I come to a stop sign its like taking off in 5th gear. No acceleration (5 minutes+ to reach 55)
After the motor cools off again, it runs good as new again.

What I've tried:
Cleaned MAF sensor using every trick on youtube.
Drove with/without MAF plugged in - no change
Drove with/without Cam sensor plugged in -no change
Unplugged MAF sensor while idling - no change
Plugged it back in, motor hesitates for a split second, and once it actually died.
Reset the computer twice.

to me, most signs point to a stopped up cat. however, whoever owned this wonderful machine before me welded on another muffler at the back, so basically it has the cat, and 3 muffs! The big square one at the rear axle well, the factory rear muffler, and an aftermarket muffler welded right behind it. I'll add photos in just a moment. I'm wondering if all this back pressure could be causing the problem, acting like a stopped up cat, no car should have 3 muffs!

Any advice that can be given will be treated as gold, because I have no idea where to start. I'm heading back to the Military in the winter, and I want to take her along with me, as this is the first VW I've ever owned, and I really love it.

If you need any more info, let me know!

EDIT: Here's pics

First one shows where the cam position sensor is on the distributor for this motor. I went through hell to figure out where it is.


Next is The MAF sensor. I'm sure you know where it is but still.


This is the Cat.


Looks like the Cat has already been replaced, to me, anyway :/


First muff. rear axle well


These next two pics show the second and 3rd muffs (3rd muff being the tailpipe) and the fact that they're welded right behind one another.

 

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Discussion Starter #2
At the very least, where would you start? Because all 4 codes will cause the same symptoms and problems
 

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That cat is definitely not stock, it's been replaced. That muffler system is ridiculous, i thought they were pretty silent stock.

Which bank does it say for your O2 sensor? Looks like you have a pre and post cat O2 sensor. The O2 sensor might be at fault, it's not telling the ECU to go into closed loop and it stays in open loop when hot. When the car is in open loop, it doesn't read any signal from the sensor itself.

Also a cheap thing to replace, and regulates the fuel mixture system as well as helps determine if it goes into closed or open loop is the coolant temperature sensor. Replace that first, it's cheap and easy to replace.
 

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Discussion Starter #4
yeah I'm gunna cut all three muffs off and have just the aftermarket one put back on, I like a little noise anyway :) I had no idea what the stock cat looked like, but it is def. not the original, at least I've never seen one with welds like that. I believe it's bank 2 sensor, but I'm not sure, which is why I suspected the cat.
 

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Discussion Starter #6
Also a cheap thing to replace, and regulates the fuel mixture system as well as helps determine if it goes into closed or open loop is the coolant temperature sensor. Replace that first, it's cheap and easy to replace.
I've seen that over and over, I never thought it applied to mine since it wasnt having any temp issues and no related codes. Can you link me to a post on how to replace it? I would search, if I could figure out which is the proper search bar.
 

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It's located on the drivers side of the cylinder head on the coolant flange. Check my sticky at the top of mk3 forum.

Just unplug the harness, pull the metal clip (Holds sensor in the housing) out upwards then pull the sensor out. Then plug the new sensor with o ring in as quick as you can before you lose too much coolant. It's really easy.
 

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Discussion Starter #8
It's located on the drivers side of the cylinder head on the coolant flange. Check my sticky at the top of mk3 forum.

Just unplug the harness, pull the metal clip (Holds sensor in the housing) out upwards then pull the sensor out. Then plug the new sensor with o ring in as quick as you can before you lose too much coolant. It's really easy.
alright thanks very much!
 
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