2003 TDI Jetta Wagon Rough Idle

dieseldoggy

Member
Joined
Apr 25, 2014
Location
Indiana
TDI
2003 Gold
My wife's 2003 TDI Jetta Wagon has developed a rough idle. Engine shakes way more than my Golf. Not indicating any codes or check engine light. Runs good and turbo kicks like normal but drives me crazy at idle. No leaks at injection pump. Cannot detect any vacuum leaks. Starts quickly. Has had injector cleaner added to each fillup most of it's life. However not lately as the wife does not have a mechanical brain and usually forgets this task. I have run sea foam thru the tank but does not help. Mileage is 201K. Has had good maintenance all it's life. My 2003 Golf idles purrs like a kitten at idle with 251K. Anyone have any ideas? Both of our cars are TDI 5 speed manual transmissions.
 

miningman

Veteran Member
Joined
Sep 3, 2007
Location
alberta
TDI
2003 Golf
Get a code reader and start investigating group 13 etc . Information you have provided is totally inadequate to even make educated guesses.
 

jokila

Vendor
Joined
Dec 3, 2004
Location
Houston, Texas
TDI
2003 Jetta GLS, Manual
Most likely based on what you are describing (rough idle. ok above that.) the Injection Quantity of the injection pump is too low. This would indicate overfueling.

Look up how to set the proper IQ. You will need access to VCDS. If it cannot be done through that, then a hammer mod is necessary to perform.
 

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
Here in EU PDs appeared in 2002.
Yea, we just ignore you guys. Best we know right up front you're not from North America or we get confused. 3 letter engine codes really help, we're unfamiliar with the various model names.
 

Franko6

Vendor , w/Business number
Joined
May 7, 2005
Location
Sw Missouri
TDI
Jetta, 99, Silver`
Although injectors can give rough idle, it's usually the IQ (injection quantity) that needs to be addressed. For example, if your injectors are perfectly balanced, with block 13 numbers at 0.00mg/str across the board (no, I've never done that, but come real close...), but the IQ can be a 1, when it should be at, who knows, 5.

When injectors get older, they tend to leak. I agree, running something like Power Service makes the nozzle very clean and therefore, able to maintain needle seating. But under the best of circumstances, nozzles age and will emit more fuel as they age. Raising the IQ can compensate(higher number = less fuel) for some of the excess fueling. If you haven't seen it, look up 'hammermod' and yes, you do need to get the VCDS to get it done well, but some might experiment and get it closer.

Jokila has a link to the Kerma sponsored page, but when it comes to the security socket, we are less than enamored with the device. It's expensive and tends to wear out. We make our own out of a 6 pt 7mm 1/4" drive socket. With a die grinder and a small carbide file, cut three of the hex flats, 120 degrees apart, until you can just lightly hammer it onto the security nut.

Although there are some that make a tool that works, there are some that are hard as lead. We ruined one POS with the first use. Since then, we make our own and sell the socket for a whopping $7+ shipping. If you'd rather, make it yourself.
 
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JETaah

Vendor , w/Business number
Joined
Jan 18, 2001
Location
mi 48836
TDI
96 B4V, 1999.5 jettaIV,2005 BEW Beetle
I would not discount the idea of a blown out dual mass flywheel if the injector balance looks good.
 

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
I would not discount the idea of a blown out dual mass flywheel if the injector balance looks good.
That's a sound guess as well. I've been told a bad dual mass flywheel will make excessive noise when simply revved high right in the driveway.
 
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