super rich fuel mixture

85

Asked by Dec 22, 2012 at 01:52 PM about the 1990 Volkswagen Passat 4 Dr GL Sedan

Question type: Maintenance & Repair

Hi, I have a 90 Passat with the 2.0L DOHC and recently installed a K&N OE replacement filter wich did wonders for fuel
economy and performance but then i had issues with my cateletyc converter. I wanted to get a little more performance out of
it so my dad and I tokk the cat out emptied all the baffles so it is completely hollow now and then we put it back on. i noticed a
drop in fuel econemy but the car was running fine and it sounded great and it did just what i wanted it to do with
performance.

now for the issue, ive noticed with winter coming as the temp drops below 50 F the car is idling super high and not dropping
until i drive for 20 minutes or so ive also notice my fuel econemy plumit. ive checked the plugs and they show small amounts of
carbon deposites and a strong smell of fuel. my exaust also smell very rich.

so i was wondering if i opened the system up to much or i forgot to adjust something for the more open system.

-- thanks in advance

3 Answers

93,805

How is the coolant temperature? It sounds like the thermostat might be stuck open. If the temperature is up where it should be, try replacing the upper O2 sensor.

85

Temps fine ill take a look at o2

17,345

The cat creates backpressure which helps the o2 sensors get a correct reading (maybe the running rich). It only uses those sensors after it warms up a bit (maybe the 20min thing). Also is the K&N filter oil charged? It will or may have already damaged the MAF.

Your Answer

Add photo

Related Questions

  • running fine,then bucks 3 answers

    Hello,we have a 1996 Passat 4cyl. It purrs like a kitten,but after 10 or 15 min. it bucks like crazy.The refs go up and down with some back-fires.We installed new plugs, wires,fuel filter,fresh gas.(e...

    1997 Volkswagen Passat 4 Dr GLX V6 Sedan

    -

    Maintenance & Repair

  • Noise on cold start 5 answers

    Recently purchased a 2003 VW Passat GLX 4 Motion for my teen driver. Have noticed that upon a cold start the car makes an unusual noise near the front of the engine. Lasts for only about a minute ...

    2003 Volkswagen Passat GLX 4Motion

    -

    Maintenance & Repair

  • 2000 VW Passat rpm drops cuts off when stops 1 answer

    Please help! have a 2000 VW Passat about 110k miles on it and my check engine light is on. I had it ran and the codes that popped up were P0441 Evap control system incorrect purge flow P0134 H02S (...

    2000 Volkswagen Passat GLS V6

    -

    Maintenance & Repair

  • 1992 VW Passat won't start 16 answers

    My son's 1992 VW Passat died about 200 feet from our house. There were no problems before it died. Now it turns over but won't start. The mechanic thinks it's a bad fuel distributor, but isn't sure....

    1992 Volkswagen Passat 4 Dr GL Sedan

    -

    Maintenance & Repair

  • I have an 82 rabbit and its running very rich and i have no idea on where to even start on fixing it 2 answers

    Also can having a higher amp alternator and higher cca battery harm anything?

    1982 Volkswagen Rabbit 2 Dr Base Convertible

    -

    Maintenance & Repair

Passat

Looking for a Used Passat in your area?

CarGurus has 20,849 nationwide Passat listings starting at $1,800.

ZIP:

Search Volkswagen Passat Questions

Volkswagen Passat Experts

#1 tenspeed
tenspeed
Reputation 1,160
#2 Tom Demyan
Tom Demyan
Reputation 1,120
#3 valeriewalk
valeriewalk
Reputation 990
View All

Related Models For Sale

Used Volkswagen Jetta
467 Great Deals out of 31,187 listings starting at $150
Used Honda Accord
814 Great Deals out of 81,559 listings starting at $899
Used Toyota Camry
1,095 Great Deals out of 96,233 listings starting at $1,250
Used BMW 3 Series
1,371 Great Deals out of 37,814 listings starting at $1,700
Used Honda Civic
663 Great Deals out of 77,395 listings starting at $1,000
Used Hyundai Sonata
608 Great Deals out of 51,117 listings starting at $1,300
Used Nissan Maxima
345 Great Deals out of 25,215 listings starting at $1,400
Used Volkswagen Golf
30 Great Deals out of 2,447 listings starting at $1,200
Used Volkswagen GTI
94 Great Deals out of 6,112 listings starting at $2,299

Used Cars For Sale

2017 Volkswagen Passat For Sale
11,621 listings starting at $15,580
2016 Volkswagen Passat For Sale
5 Great Deals out of 1,105 listings starting at $12,295
2015 Volkswagen Passat For Sale
57 Great Deals out of 2,718 listings starting at $9,741
2014 Volkswagen Passat For Sale
32 Great Deals out of 822 listings starting at $7,450
2013 Volkswagen Passat For Sale
42 Great Deals out of 1,038 listings starting at $5,000