poor fuel economy

[vr6 jett-n]

Please Help!!, i own a 1998 vw jetta vr6, after a recent tune up (change of wires, and plugs bosch +4) my fuel econmy instead of getting better got worse!...especially when driving in traffic. The trip computer shows on average 13L/100km, and there is a weird and really suddle smell of gasoline blowing thorught the wents. Around the same time i also installed the K&N air filter, could this be the problem?...i was thinkinh that it might be my O2 sensor thats slowly retiring, but my check engine light never went on yet!...PLEASE help!

[boschmann]

I would first check for gas leaks at the fuel lines, injectors, etc.... Is there a black soot building up inside the tail pipe? Did you oil the new air filter? VW's are pretty good about turning on CEL when an O2 goes bad.

[vr6 jett-n]

Originally Posted by boschmann

I would first check for gas leaks at the fuel lines, injectors, etc.... Is there a black soot building up inside the tail pipe? Did you oil the new air filter? VW's are pretty good about turning on CEL when an O2 goes bad.

Thanks so much for the prompt reply!, there are no leaks around the fuel lines and the funny smell seems to be concentrated around the throttle-body, as it goes for the filter i never oiled it since it came pre-oiled (at least thats what the box said). Is it possible for the O2 sensor to be acting up even is the check engine light does not go on?

[losbourn]

My Jetta 2000 was swallowing gas for about 2-3 weeks before the check engine light came on.

Thankfully there was a recall on that O2 senor and VW took care of it.

Originally Posted by boschmann

I would first check for gas leaks at the fuel lines, injectors, etc.... Is there a black soot building up inside the tail pipe? Did you oil the new air filter? VW's are pretty good about turning on CEL when an O2 goes bad.

[boschmann]

Sure, it's possible for O2 to be bad w/o a check engine light, just not too common about the same as with a bad MAF. If there is soot building up from running rich then it's time to look into that possibility. You will need a scan tool capable of looking at the computer's datastream and someone with the ability to interpret the info. I don't remember which years & engines were involved with the recalls and warranty extensions, but 2000 is right in there. Most independent professional repair shops can check this out for you. I have noticed an unsettling trend with VW dealers charging diagnostic fees even if the defective item was under warranty or recall. And if they don't find anything they will definitely charge you a basic diagnostic fee, at least an independent will probably charge you less. Are you over 70K miles (I can't remember the Km equivalent)?

[vr6 jett-n]

Originally Posted by boschmann

Sure, it's possible for O2 to be bad w/o a check engine light, just not too common about the same as with a bad MAF. If there is soot building up from running rich then it's time to look into that possibility. You will need a scan tool capable of looking at the computer's datastream and someone with the ability to interpret the info. I don't remember which years & engines were involved with the recalls and warranty extensions, but 2000 is right in there. Most independent professional repair shops can check this out for you. I have noticed an unsettling trend with VW dealers charging diagnostic fees even if the defective item was under warranty or recall. And if they don't find anything they will definitely charge you a basic diagnostic fee, at least an independent will probably charge you less. Are you over 70K miles (I can't remember the Km equivalent)?

Thanks for all the help!, i got 180K on it right now, but i think i found the problem. The ignition module to had a tiny crack in it as i sprayed the module with water sure enough it was shorting with one of the wires!,....so handy me i patched the crack with epoxy, and sparyed all the components with ignition dry spray!....i also filled up the car with 91 octane gas, i used the middle one before.....and everything went back to normal again!...the car seems to be running much smoother and the acceleration is way better!...the fuel economy went back to normal too!....now we'll see if it's gonna last! the only thing that i noticed now is that one of the timing chains is making a grinding noise!,it seems to be coming right form the rear to of the engine where the collector is i thought they lasted for the life of the car, what could be wrong with it!?...this car is gonna make me go bankrupt!