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Discussion Starter #1
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
(no answers no matter what I do on mk3 forum)

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!



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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I'm going to go ahead and rule out exhaust and maf. When the maf is bad it should run better without it. With exhaust it shouldn't get worse when it's warmer, it should just be crappy in general. Your 02 sensors could be culprit still. Reading some screwed up stuff, but they also could be reading crap your pvc is dumping.

Should check for leaks in your intake and intake manifold with some wd-40
Check for cracked/ripped pvc parts.

How is your pvc system doing? Are you burning oil/smokey exhaust?
Remove your oil cap and put your hand over it. Does it feel like its sucking your hand in or blowing air?
 

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Discussion Starter #4
Your suggestion just reminded me that someone else suggested to check the intake tube :/ thank you for your suggestion! I'll get it jumped off in the morning (batt dead cuz "vw tech" came out and reset the computer but left my batt connections loose) and ill check in the morning :) I've got some carb cleaner ican use instead of wd-40. The PVC is gunked up, but I didn't think it would cause this big of an issue. Should I pull the O2 sensor and check the discoloration?
 

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wd-40 is less likely to start a fire since it has a much higher ignition temp.

Check the intake and pvc first. Causes all sorts of problems.
o2 sensor. I'm not sure how discoloration would tell if it's bad to be honest.
You can hook up vag-com and see if everything's giving readings in real time.
 

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Discussion Starter #7
I won't start a fire :) I know a little about what I'm doing, I'm just 1 not familiar with vws and 2 the newest car I've owned before this was an obd1. I'm getting a vag com cable this weekend :) if I can't tell by discoloration, can I hook a meter to the o2 sensor? What should the readings be? I guess the cable will tell me the same info :/
 

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Discussion Starter #10
No I haven't replaced it, I just unplugged it and drove. There was no change. I thought that there would be a definite change if it was the problem.
 

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Discussion Starter #11
I'm no good at timing so I don't want to yank the distrib. And tear it apart if I can avoid it, and I surely don't have the $$ to buy a whole new distributor just to find out if the sensor is the problem
 

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Discussion Starter #13
And that makes sense. Too bad this forum is full of advise that says to unplug the cps and see if there is a change :/

None the less I can't afford a new distrib. Nor am I comfortable doing timing, so I'm going to try the first suggestion first. Though the cam sensor has been my suspect for a long time. Because the cam sensor controls fuel timing, and my thought was that it seems like it runs out of time but returns to normal after it cools. Almost like it has a faulty variable timing sprocket (if it had one, lol)
 

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I don't think timing of your spark is the problem. I wouldn't touch the distributor.

Try checking for leaks then maybe address that cam sensor if it doesn't clear up.

You can search youtube for an 02 sensor test. Lots of good info on it. Requires a multi meter and a lot of care.
 

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Discussion Starter #15
I don't think timing of your spark is the problem. I wouldn't touch the distributor.

Try checking for leaks then maybe address that cam sensor if it doesn't clear up.

You can search youtube for an 02 sensor test. Lots of good info on it. Requires a multi meter and a lot of care.
the cam sensor is in my distributor, and it controls the timing of the fuel delivery, and it feels as though the engine slowly goes out of time. the way i understand it, it detects knock and then retards timing by 1 degree then cycles again, if it detects knock again it retards timing again and cycles up to 4 degrees. wait maybe that's the crank sensor... if so then the cam sensor reads out of range it dumps too much fuel to make up, which is why i could be getting the too rich condition across all sensors. my two primary suspects have been the cam sensor and the 02 sensor. Cam sensor I have to pull the distributor, knock the bottom gear off pull it apart and replace the sensor then put the dist. back together then put it back in the engine and re-time. I dont wanna do that :/ i will look at how to check the o2 sensor, after i make sure they're plugged in properly
 

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Discussion Starter #16
Took the batt to be charged yesterday, and as it turns out, the vw tech killed it completely. It won't take a charge and bulged out on the sides :/ now I have to replace it too :(
 

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update

Ok so here's an update, I put a new timing belt on, and it didn't change anything. I bought the coolant sensor but it was the wrong one, so I sent it back and could not afford the other. i drilled a small hole infront of the three muffs and noticed a small but noticable difference, so I unbolted the exhaust system at the cat and secured it bvery well to the body of the car and took it for a spin and let me tell you

WHAT A BEAST! it was like driving a totally different car! All the power returned hard pulls into 3rd gear, tires break loose, smooth revs to 5000 RPMs even once its been ran for a hour, black streaks on pavement....

Ok I pushed it a little hard, but I was literally going to post in craigslist today for $500 obo come get it tonight first cash offer gets it if I didnt find the problem

But it did. either the cat is plugged up or one of the muffs is, or there is simply too much back pressure. so I'm going to get the exhaust system re-done and it will be fixed :) hopefully the codes go away too.
 
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