[vwbuge]

Picked up my 2004 Passat W8 a few months ago. Has been running better than ever since I brought her home. 91k miles and PO had a bumper to bumper warranty so a lot of stuff has been replaced. Anyway, installed a K and N filter today and took it to work. Ran awesome. Got in car to go home and started great, idled great but when I give her gas she bucks moderately. It is like I am on and off the throttle. Still accelerates fairly hard. No check engine light and I ran my OBD II. No codes.

Off the bat I am thinking fuel filter. Anyone had any issues like this?

 

[vwbuge]

I am thinking I put too much oil on the KandN and it got on the MAF. I am going to clean it and see what happens.

 

[BlackJelli]

Which Filter?

Did you put in a standard sized panel filter or a cone shaped filter? One or the other will provide different results. There have been some complaints about the oiled gauze filters fouling the MAF, but I don't know if that is over time or if it can happen immediately. Your problem sounds like it could be electronic in nature. You might want to install a stock paper filter to minimize the variables in the problem. I have also heard of a spray cleaner designed for the MAF sensor that could help, if indeed the filter dirtied the sensor. Good luck!

 

[vertigoeffect]

Im thinking you should start at the air box and work your way to the throttle body and ensure your hoses are completely connected and clamps are back in place. I run a K&N panel and have removed all baffles and pre-screen that filters leaves and large road debri from entering the air box. Basically I have to clean my filter and re-oil it every 3-6 months depending on what season it is and sometimes I forget to slide one of hose clamps back in place. Under heavy throttle the hose backs itself out a bit and introduces air after the MAFS and this causes the issue you described. I hope this all it is for you. Also I have never had a problem with K&N oil on any of my VWs. If you follow the directions to the letter when cleaning it and reapplying oil you'll be fine. Its the folks that over oil the filter and immediately put it back in and run the car that have problems. If the filter is completely dry after cleaning and you let it sit for a couple hours after oiling it will be fine. Good luck and keep us posted.

-David

 

[VWPassatW8_UA]

heat shield is what you need that helped me i also made a custom cold air by cutting through the body of the car on passenger side wheel well just above the tire when you remove oem box you will see what im talking about no problems for me

 

[vwbuge]

Im thinking you should start at the air box and work your way to the throttle body and ensure your hoses are completely connected and clamps are back in place. I run a K&N panel and have removed all baffles and pre-screen that filters leaves and large road debri from entering the air box. Basically I have to clean my filter and re-oil it every 3-6 months depending on what season it is and sometimes I forget to slide one of hose clamps back in place. Under heavy throttle the hose backs itself out a bit and introduces air after the MAFS and this causes the issue you described. I hope this all it is for you. Also I have never had a problem with K&N oil on any of my VWs. If you follow the directions to the letter when cleaning it and reapplying oil you'll be fine. Its the folks that over oil the filter and immediately put it back in and run the car that have problems. If the filter is completely dry after cleaning and you let it sit for a couple hours after oiling it will be fine. Good luck and keep us posted.

-David

That was it. My own stupid mistake. I bought some spray MAFS cleaner and sprayed it down. I put everything back together and checked all the inlet pipe and electrical connections. Sure enough, the plastic tubing where it enters the intake was off just a bit. It must have come loose from when I installed the K and N. All better.

 

[VWGUY4EVER]

You'll NEVER have MAF / K&N Oil issues if you follow this cleaning/oiling guideline of mine. I had one in my Jetta for 125,000 miles, two years and about 40,000 miles in my 2001 GLX before I moved it to the W8 - same flat panel filter - for 70,000+ miles.

- Spray the filter with the cleaner (basically Spray-9 if you run out) and let it sit for 10-15 minutes.
- Rinse with a low pressure stream of water - usually did it in a sink - then repeat.
- Let dry for a day. As the directions say, DO NOT use compressed air or let it bake in the sun.
- Oil both sides. Let stand for 10-15 minutes and spray just a little more to cover evenly. Let sit for a day. Before installation, lightly tamp the filter on a rag or paper towels and wipe all around the seal to remove any excess.

I kept the original filter so I could drive the car with the K&N out...