# 2002 Jetta 2.0L - Rough Idle and Loss of Power - Replaced bad spark plugs



## kingstonjetta (Jan 18, 2015)

Hi everyone, newbie here with a couple questions!

Car in questions is a 2002 Jetta 2.0L, with 173,000 KM.

So, yesterday I was driving from Ottawa to Kingston, and about halfway through the trip I started to get really sluggish response from my car. It felt almost as if it was trying to make it up a hill with a heavy load. I pulled over and the idle was rough, but we were only a few KMs from home so we kept going to try to take a look when we got back. Had trouble keeping it over 80KM/hr and making it up hills.

I took it into Midas today, and they replaced the spark plugs and wires. The old spark plugs had worn on two cylinders so bad they didn't have the electrodes anymore, it was worn almost flat. So this of course had to be done.

After replacing them, the car has gained some power back, but still runs rough, lacking power (but not as bad as before) and idles rough. I can now keep it at a regular driving speed, but it still sounds bad and isn't how it was running when I got it. Also has really bad response between 2000RPM and 3000RPM, and runs loud. The rough idle at stop lights has a pattern of it being bad, then worse, then bad, then worse, which can be timed to a regular pattern (hope that makes sense). 

The shop is closed on Sunday, so I will be taking it back in on Monday to have a more thorough look. 

My main questions are:
1. What kind of damage could a worn out spark plug do to the engine?
2. How likely is it that a valve issue has developed, meaning big $$ to repair?
3. How much should I expect for a valve repair in Ontario?
4. Is there anything I could look into in my driveway while I wait for the shop to open?

I've heard similar issues be attributed to MAF sensors, O2 sensors, vacuum issues, fuel pumps...
I just don't want to have all these issues fixed, then find out the real issue is a $2000 job that I would scrap the car for.

Thanks!


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## rommeldawg (May 25, 2009)

have you scanned the car for codes... was cel on when you took it in the first time? if yes, was it cleared? is it on now?


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## kingstonjetta (Jan 18, 2015)

Didn't get the codes scanned yet, and no CEL at all. 

Real symptoms right now are the rough idle, lack of power, and high gas consumption.


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## roadsterred (Feb 25, 2010)

Have you considered dirty fuel injectors?


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## eimajamie (Jul 29, 2008)

There is a technical bulletin from Volkswagen which instructs you to add a ground wire to the connector at the coil pack and run it to a good ground on the body. It fixed my misfire.


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## VeaDoubleYou (Apr 17, 2014)

If you seem to have any other misfires, try replacing the coilpack. The coilpack on mine was cracked starting to rot. I changed it along with new wires and spark plugs. Idle is no longer rough and i can feel a bit of extra power. Car runs like new, even if it has 257,000km.


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## eimajamie (Jul 29, 2008)

Still misfiring. Going to replace coil now... Not wanting to pay dealership price for one though...


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## Anony00GT (Mar 6, 2002)

eimajamie said:


> Still misfiring. Going to replace coil now... Not wanting to pay dealership price for one though...


You get what you pay for. Aftermarket coils often don't work, or can even kill ECU's.



eimajamie said:


> There is a technical bulletin from Volkswagen which instructs you to add a ground wire to the connector at the coil pack and run it to a good ground on the body. It fixed my misfire.


Yes do this as well. Run the ground directly to the battery negative post.


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## eimajamie (Jul 29, 2008)

Ah makes sense. I ran my updated ground to the body ground under the battery.


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## Anony00GT (Mar 6, 2002)

eimajamie said:


> Ah makes sense. I ran my updated ground to the body ground under the battery.


That's the TSB way to do it, and technically not wrong.

But battery negative is a better ground point than anywhere on the chassis, IMO. Since the coil is pretty close, why not go directly to the battery instead of underneath it?


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