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Discussion Starter · #1 ·
Got a 2000 NB with 398k on it...runs great stone cold...once it warms up it acts like only a couple cylinders active...can only get it up to about 45mph and that on a downhill...haven't noticed the cooling fans coming on...the radiator hasn't blown fluid that I would normally associate with it overheating...thinking it might be coils or vacuum ...away from my home shop so have limited tools.
Any ideas of what's going on?
Thanks
 

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I would start with getting the car scanned for trouble codes; post up any codes you get (numbers, not just descriptions).

If you are getting misfires and you suspect the coil; you might try this diy: VWVortex.com - DIY/Troubleshooting - Coil pack on 2.0 AZG, AVH, BEV, or BBW

Tell us more about the history of the car; when was the last time, there was a tuneup done, any major repairs done in the last couple of years and has the engine ever been rebuilt? Did this problem; happen all of the sudden?
 

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Discussion Starter · #3 ·
More Info

Thanks billymade for your reply....here is a bit more info...
First to address your questions:
1) Tell us more about the history of the car;
bought it new in 2000...once the warranty was up at 45k been doing all my own service (except mounting tires) to include:
2 cat replacements
20 headlight bulbs
5 sets of tires
2 drive shafts
every 5k...oil/filter
three sets of seat covers
rear hatch holder-uppers
2 water pumps/belts
1 new radiator
3 sets of brake pads
2 fuel filters
1 fuel pump (I think)
4 oxygen sensors at least (those buggers are pricey)
1 coil pack
1 clutch cable
lots of vacuum hose


2) when was the last time there was a tuneup done
start to get embarrassed here...usually keep the filters changed but the plugs are such a bugger the last time I did those were about 100k ago...put good ones in cuz I new it would be a while before I would do it again

3) any major repairs done in the last couple of years and has the engine ever been rebuilt?
no major repairs done except for a radiator replacement...engine never been rebuilt

4) Did this problem; happen all of the sudden? "
This problem has happened about 2 times/yr since we bougth it. Been thinking more about it and experienced it again today so here's another explanation.....driving along fine without issue then, like a switch, it goes to about 25% power...seems like multiple cylinders go dead...what I do to get it back to "normal" is to immediately drop it down a gear or two and get the rmp up to 5-6k then the switch changes back and all is fine again....happening every day now...if at idle and it happens I can rev the engine to 5-6k again and it fixes it.

Got a list of the codes it threw today (cleared em last night):

P0422
P0300
P0302
P0303

Initially I though it might be the fuel filter/pump but I would think that would gradually degrade and not get better...
Maybe the coils but there are reasons why that prolly isn't the reason either....maybe another oxygen sensor but it prolly wouldn't get better either....
Any thoughts would be GRATEFULLY appreciated...
Thanks
Tom
 

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16806/P0422/001058 - Ross-Tech Wiki

16684/P0300/000768 - Ross-Tech Wiki

16686/P0302/000770 - Ross-Tech Wiki

16687/P0303/000771 - Ross-Tech Wiki

Well, my initial thoughts are a number of things; pinpointing the problem, could be helped by looking at "live data" and seeing what your fuel trims are:

Fuel Trim Info - Ross-Tech Wiki

Posting up what your current fuel trims are; can give us a sense of what your engines tune is. You have a TON of miles; on a gasoline engine and from what you are saying, no internal repairs up to this point.

Based upon the above issues; you are having misfires and your catalytic converter is possibly not working as it should.

I would be looking at fuel pressure, vacuum leaks, low compression, dirty throttle body, coil pack failure, bad spark plugs/wires, bad ecu and possibly a clogged catalytic converter. These are just guesses; a live data capable scan tool, would help you see what is going on. Let us know; what type of scan tool you have access to: you might want to purchase a ELM 327 obd II wireless adapter and a app like OBD FUSION, to run on your phone or tablet.

ELM 327: wifi for apple/ios and bluetooth for Android:

https://www.google.com/search?q=ELM...9i57&sourceid=chrome&ie=UTF-8#q=ELM327+amazon

OBD FUSION: ios and android:

https://www.google.com/search?q=obd...rome..69i57.1927j0j7&sourceid=chrome&ie=UTF-8

Here are some threads; that can show you some testing and ideas on what to look for.

coil pack testing:

VWVortex.com - DIY/Troubleshooting - Coil pack on 2.0 AZG, AVH, BEV, or BBW

Volkswagen Workshop Manuals > Beetle L4-2.0L (AEG) (2000) > Powertrain Management > Ignition System > Ignition Coil > Component Information > Specifications > Electrical Specifications

fuel pressure testing:

Volkswagen Workshop Manuals > Beetle L4-2.0L (AEG) (2000) > Maintenance > Tune-up and Engine Performance Checks > Fuel Pressure > System Information > Specifications > Pressure, Vacuum and Temperature Specifications

compression testing:

Volkswagen Workshop Manuals > Beetle L4-2.0L (AEG) (2000) > Maintenance > Tune-up and Engine Performance Checks > Compression Check > System Information > Specifications

If you haven't looked at your plugs; in over 100k, that might be a good place to start and plug wires, checking the coil for cracks, could be a good basic check as well. Fuel pressure and compression; basic checks, would be nice to cross off the list, as you have such a high milage engine.
 

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Discussion Starter · #6 ·
Running Problems

Thank you for the invaluable info...I'll go through each one...and tend to the pugs/wires early on....I had a program and rs232 cable (strung it from my desktop...wife didn't think it was too cool) many years back that I attempted to use without much luck...looks like fun stuff....
Good to hear about the oxygen sensors too....
Thanks
Tom
 
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