Low power, vibration in mid rpm

2002 Jetta 5 Speed, 185,000 miles. Starts and runs well, but power is way down. Can't maintain speed on the hills and seems to run out of power at around 3,000 rpm in any gear. Also has a pretty significant vibration under heavy throttle between 2,000 and 2,500 rpm.

I just cleaned out the intake manifold (thanks for the info); also replaced a bad MAF about 10,000 miles aago. The intake manifold was pretty gunked up, and cleaning it seems to have improved the power some but definitely has not solved the problem. (I'm really kind of amazed it ran as well as it did with all that restriction.)

The only code I get (with my OBD II scanner, not a vag-com) is P0673 - Glow plug heater cylinder 3. I've been getting this for a few months, and replaced the #2 and #3 plugs, but the code comes back. And it starts fine, so I pretty much ignore it.

Any thoughts?

Thanks.

When was the last time the fuel filter was replaced?

Filter is good, though it does feel just like that. It was recently changed, with no improvement. I should have included that info.

Have you looked through the FAQ's - here's the section on low power. Might help.

Yes, I went through that, which did point me to the intake manifold possibility. And so many other problems sould throw a code.

Is a clogged catalytic converter possible? Or would this show up as a check engine light too?

I saw that you changed the maf awhile ago have you tried to disconnect it and try driving to see if there is any difference, i had one fail 13000 miles after the dealer changed the last one under warrenty this one was my nickle

Interesting idea. I pulled off the MAF plug, and it didn't drive much different. Maybe a bit worse, but not a lot worse.


But could the MAF be bad and not give a code and a CEL?

Yes thats what happened to me,(no code low power) you will get a code when you pull the maf plug off.the ecu sets the values to a mid range position because it does't see the maf input, if you see a noticeable difference that might fix your power problem if not chances are the maf is good. I noticed that you run with a veg mod,does this happen when you run straight diesel?

Yes, runs exactly the same on either.

I have been experiencing exactly the same........

as you described. My power is way down too and at about 2000 rpm I feel like its time to shift gears because it feels like something is clogging up and on the slightest hill I have my foot down to the floor but am not moving. My car is at a shop and they had a lot of trouble diagnosing so they brought it over to the dealer. I was just told the consensus is that I need a catalytic converter ($900). After "choking" on the price (I thought it would be a fuel related simple repair after reading the FAQs) I agreed to go ahead with the repair.

Any thoughts?

Thanks!

It sounds possible - I don't know if a clogged converter would throw a code.

If they change the converter, for 900 dollars, they better be right. On the other hand, there are alternatives to replacing the converter, but your dealer will not be able to do them.

RIRed, keep us posted on your catalytic converter issue. Sounds like I'm having the same troubles as you are. Cat was on my short list of possible causes after having tried pretty much everything else.

Converter replaced, problem remains....

Hi again, The replacement of the catalytic converter didn' solve the problem...although supposedly there was a code indicating that I needed a new one (I am skeptical due to the fact that this was a "consensus" opinion and didn't solve the problem). I have been working with a VW garage that brings problems that are beyond their realm to the VW dealer. The dealer gave the car back and thinks that it is the pump.....It seems like they keep finding high ticket solutions that don't work! I too remain perplexed.......

Okay, how's the MAF?

check the troubleshooting low power link

How's the static and electronic timing of the engine?

And VAG-COM folks in your area?

Could be the throtte position sensor I'm told. You can check in VAG-COM if the computer is seeing WOT when you've got it floored.

I'm still having trouble with mine. Top speed is about 80mph. Acceleration is way down. No smoke whatsoever. Feels like it's really, really under-fueled. Gonna check with VAG-COM on how much fuel is being delivered soon.

check timing, injected quantity, scan for codes, check N75 for useage (should be around 45% or higher... if it's lower... check catalytic converter, or improper camshaft timing)