Treating a 2003 Jetta

[llmercll]

My Jetta is beginning to get a rough idle and "[censored] like" acceleration at lower speeds. Tomorrow I'm going to clean the throttle body and MAS with some CRC cleaner. Is there anything else I can do that's generally recommended?

It's a 2003 Jetta with 230k miles on it.

 

[Bjornviken]

Ac?

 

[dlundblad]

Fuel filter would be another cheap place to start.

 

[mx5miata]

injectors, plugs?

 

[Kira]

Also cheap to do is adding a bottle of Techron concentrate to a tank of gas before a stint of non-highway driving.

Make sure your air filter isn't neglected.

16 MY old car??? Inspect all air / vacuum handling hoses.

 

[RooflessVW]

2.slow or 1.8t?

It's probably coils.

 

[2004tdigls]

or a plugged cat converter

any MIL codes from an OBD2 scan??

 

[BrocLuno]

A plugged CAT won't allow it to rev under load. If it will still pull in the upper RPM ranges, it may be a throttle position sensor. They wear mostly in the lower ranges what they get the most use ...

Could also be the ground loop between the engine (and its sensors) and the ECU. Try adding a new fresh healthy ground cable between the battery Neg (-) pinch bolt and the engine near the alternator and extending it to the firewall on a convenient bolt. All crimped and soldered lugs on say #8 or larger wire. You may see an immediate difference ...

 

[Audios]

After you clean the throttle elave the key forward for a minute or so, it should do an adaptation. Are there any faults present or blinking check engine?

 

[bullwinkle]

All else fails, do a compression test on it. Hope it's something easier.

 

[maxdustington]

2003 best year!

 

[pezzy669]

I remember MAF (Mass Airflow Sensors) were problematic on pretty much all VW's of this era for getting dirty and causing all sorts of drive-ability issues so you are on the right track there with cleaning it.

2.0 had and probably still issues with the coil pack allowing moisture in and causing misfires in damp/wet conditions.

Like someone above said what engine do you have?