gas mileage-carbon build up
03-10-2004, 02:57 PM
#1
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gas mileage-carbon build up
hi! about last month my 99 audi a6 2.8q has been repaired for carbon build up. now when i'm driving my car i just feel there's been a significant change on gas mileage. i feel less gas mileage after the carbon job done than before. for 15 gallons i only reach 200 miles for city driving. i drive normally like always and try to minimize the stop and go driving but still i feel that the gas mileage is worse than before. any body has similar experience, is there any safe additive that can improve my gas mileage?
thanks in advance for your inputs.
thanks in advance for your inputs.
03-10-2004, 06:03 PM
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How about Power? Is it normal?
If you floor it, does the power come on like it should.....or is it slower than you would think it is.
The reason I ask is if the cats honeycomb has melted or deformed it can create a serious blockage of the engine air, the engine is going to have to work significantly harder to propel you at the same speed.
I've seen it before on a bunch of other cars, but never on a fuel injected Audi.
Just one possibility. If your performance is way down this could be one cause, power would be significantly reduced too.
pw
The reason I ask is if the cats honeycomb has melted or deformed it can create a serious blockage of the engine air, the engine is going to have to work significantly harder to propel you at the same speed.
I've seen it before on a bunch of other cars, but never on a fuel injected Audi.
Just one possibility. If your performance is way down this could be one cause, power would be significantly reduced too.
pw
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03-10-2004, 10:05 PM
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same car, i am getting 230miles for 16 gal. i think it is because i live near nyc= city driving... o
or i better check my car?
i only have a few days till my audi assured expires. should i bring my car into dealer?
i only have a few days till my audi assured expires. should i bring my car into dealer?
03-11-2004, 07:28 AM
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I suspect something like this in my car.
It can barely get up to 125 downhill, and with 200 HP it should do better than that. It's supposedly governed to 130, for God's sake.
If I step on it sometimes I get some black smoke out the back.
I've used techron from time to time and I don't drive like an old lady so there shouldn't be carbon buildup.
There are never any fault codes according to the dealer, and they of course think its fine as long as there are no fault codes.
Well my 170 HP 90quattro saw 143, and at high speeds its a matter of aerodynamic drag more than anything, and I don't believe the A6 avant is any worse than the 90quattro as far as drag, so an extra 30hp should at least help it get it up to the limiter at 130.
What do you think: If my O2 sensors were bad, I'd get a fault code. My engine shouldn't have carbon build-up, but it might, and I don't know that a fault code would be stored. The MAF sensor should throw a code if it's bad or buggy. THe air filter was recently replaced, as were the plugs with OEM plugs from the dealer. idle is smooth, so plug wires should be OK.
However, I notice black soot on the exhaust tips weekly, indicating incomplete combustion, and I do wonder if the cats could be clogged. If they were, the result could be the car simply runs as if it were at a higher altitude (engine compensates, registers the reduced O2 in the air as normal, but makes a little less power, especially at the high end.
If it is the cats, how do I get them replaced under warranty when their aren't any codes? Any ideas?
This car is slow enough as it is, it certainly doesn't need to be dragging anchor.
If I step on it sometimes I get some black smoke out the back.
I've used techron from time to time and I don't drive like an old lady so there shouldn't be carbon buildup.
There are never any fault codes according to the dealer, and they of course think its fine as long as there are no fault codes.
Well my 170 HP 90quattro saw 143, and at high speeds its a matter of aerodynamic drag more than anything, and I don't believe the A6 avant is any worse than the 90quattro as far as drag, so an extra 30hp should at least help it get it up to the limiter at 130.
What do you think: If my O2 sensors were bad, I'd get a fault code. My engine shouldn't have carbon build-up, but it might, and I don't know that a fault code would be stored. The MAF sensor should throw a code if it's bad or buggy. THe air filter was recently replaced, as were the plugs with OEM plugs from the dealer. idle is smooth, so plug wires should be OK.
However, I notice black soot on the exhaust tips weekly, indicating incomplete combustion, and I do wonder if the cats could be clogged. If they were, the result could be the car simply runs as if it were at a higher altitude (engine compensates, registers the reduced O2 in the air as normal, but makes a little less power, especially at the high end.
If it is the cats, how do I get them replaced under warranty when their aren't any codes? Any ideas?
This car is slow enough as it is, it certainly doesn't need to be dragging anchor.
03-11-2004, 07:58 AM
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230 seems really low, but as we know it depends on driving style and maybe fuel quality
I have a 4 mile drive to work and can't get above 40 mph. Not much stop and go, but slower speeds. On weekends I see the freeway and usually drive 80 mph. I try not to accelerate too quickly. I also use 93 octane (all they have here w/o going below 91). 230 still seems low to me but I'm not sure what you'd ask the dealer to look for. Oh yeah...I have Quattro too which usually brings the gas milage down. What always bothered me is that my wife had a 2001 Passat 2.8L V6 with Quattro (4motion) and she always had better than 22 mpg. Maybe the newer engines are better?