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Discussion Starter #1
A little background here. '01 Jetta, 2.0 AZG (bad rings= bad o2 sensors, bad cat, fouled plugs etc...) I have been driving with the MAF unplugged for some time now, and finally bought a new MAF. installed, and runs like garbage. no acceleration, had to idle around the block. unplug, I can drive normally for the most part but without much power in EPC mode. Cat has been hollowed out, (plugged up due to piston blowby),both o2 sensors are new, ignition coil was cracked, replaced that, plug wires and plugs too when I blew the head gasket after the coolant flange failed... new cam position sensor(broke when rebuilding the head), and 267k on the odometer.

with that out of the way, I am actually ok with the way it drives in EPC mode, but would like to try to correct the current issues. plugged in, runs like crap, unplugged EPC mode. The other day it was extremely cold and could not get the engine to go past idle. warmed up a bit and went away, this happened 3 times but not for weeks since. I'm wondering if anyone has run into this, and if the throttle body is just shot. is there an EGR or an IAC valve on this car that I can clean? is the CAT being hollowed out causing the problems? any help is always appreciated.

Thank you,
 

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if you unplug your maf and the car is better that is telling you something is obviously wrong with either the MAF or one of your other sensors. MAF would be my 1st guess..

theres info online about cleaning the MAF sensor properly. Id start there.
 

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Discussion Starter #4
did you clean and re align your throttle body? it could be filthy
Got too pissed off because I just bought a new MAF, installed and plugged in and ran like crap again. same issue. clearly not the MAF. I wiped out some loose oily residue from the front side of the TB, and lifted the plate by hand wiping around inside, but it wasn't too bad. I should pull off and clean well, but just didn't have time last night.

I'm not used to looking at these engines, do we have EGR or IAC on these? Throttle position sensor is part of the throttle body and can't be replaced independently right?
 

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Discussion Starter #5
did you clean and re align your throttle body? it could be filthy
if you unplug your maf and the car is better that is telling you something is obviously wrong with either the MAF or one of your other sensors. MAF would be my 1st guess..

theres info online about cleaning the MAF sensor properly. Id start there.
That's why I'm here, I already bought and installed a new MAF and ran into the same issue. runs better without it in EPC. Why would that be?
 

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you realign the throttle body via vagcom. if you do not have vag com, you can still kinda realign it.

put key in ignition. turn key to turn JUST the power on. do not turn on the whole car.

under the hood, youll hear the throttle body making a real high frequency noise. this is the throttle body realigning.

leave key in this position for 2 minutes. turn the car on. it should be aligned.
 

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Discussion Starter #7
you realign the throttle body via vagcom. if you do not have vag com, you can still kinda realign it.

put key in ignition. turn key to turn JUST the power on. do not turn on the whole car.

under the hood, youll hear the throttle body making a real high frequency noise. this is the throttle body realigning.

leave key in this position for 2 minutes. turn the car on. it should be aligned.
i'll give that a shot. Would you suggest doing the re-align with the MAF connected or do that after the fact?
 

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try it with the maf connected first. if it doesnt work, disconnect and realign, then try it.


did you buy an OEM MAF? or a used/ OE one from autozone or something
 

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Discussion Starter #9
It was a re-man unit, but I'm doubtful that there is anything even wrong with the MAF at all at this point. it runs better without it, for sure, but visually the new MAF and old were identical. clean as a whistle on both, and no physical damage, started running like garbage about a year ago when the cat clogged up. couldn't climb the slightest hill in high gear because there was no air flow. hollowed out the cat and that problem was fixed, but ran really rough. plugs, wires, coil, finally unplugged the MAF and have had best performance so far... I HATE guessing.
 

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Discussion Starter #11
Have not checked for vac leaks yet, and a very likely culprit, thank you. re-aligned the tb yesterday and definitely runs better, but still falls on it's face w/ maf plugged in. so I should get a chalk dust puffer and start blowing around fittings to see if any gets sucked in?
 

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you can get a cigar or something too.

this is how you could do it without the car on.
 

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Discussion Starter #13
thanks, i'll review when I get home tonight and check it out. Just happen to be a cigar smoker.
 

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Discussion Starter #14
Update; The Catalytic converter is hollowed out. I have new o2 sensors fore and aft. I have re-aligned the throttle body and that has helped some, but still will only drive with the MAF unplugged. vac leak check is next, but I'm considering breaking down and putting in a new CAT, as I'm pretty sure the two o2 sensors are responding to the ecu which is communicating with the maf and TB and creating this goat show. Thoughts?
 

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if your first o2 sensor is getting a poor reading, then that could possibly be making your car run poorly.

mine was broken and my car was running pretty bad, so i poor reading could make it run bad too.
 

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with no cat or a punched out cat you need to run 02 spacers to avoid throwing a p0420 code and p0421 p0422
 

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Discussion Starter #17
with no cat or a punched out cat you need to run 02 spacers to avoid throwing a p0420 code and p0421 p0422
(And the light shone down from the heavens and the VW was indeed blessed)

Where would I get these miracle workers sir? thank you for the information. Are we just talking about some washers to back them out some? Please elaborate if you don't mind.
:D
 

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getting the spacers is kind of a cover up for the problem, see what rodger said, try that^


but you can get 02 sensor spacers for 42draft designs
 

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Discussion Starter #20
Roger wilco. now to find time between two jobs and kids... i'll update you as I come along. I'm pretty much done putting bandaids on this thing, and w/ 270k I would like to keep it rolling for a long time to come but I still can't bring myself to put another CAT on without fixing the piston ring issues the AZG came with, cause i'll just be doing it again later on down the road.
 
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