having an issue with my 2000 Taurus

[QueBert]

I don't possess much car knowledge, but I know something doesn't seem right. I put gas in the last few times and it seems to be going down real fast. My check engine light isn't on. So all I can think of is the car's running rich. I had both of my O2 sensors replaces last year. I do notice when I drive even a mile, when I get out I can hear the pop pop popping underneath the car. I know cars do this, but I don't remember, or think it should be doing it after a mile or 2. Can be pretty rapid and last a while too. When I say a while, maybe a minute or. This is from heat right? I know it's normal, especially when it's a hot California day. But it definitly is worse than I ever remember it. I was low on gas the other day, let it run low on porpus, put in $10 as a test. I'm up to 23 miles of slow street driving and the gauge went from a quarter of tank to a little less than half that.

A few weeks ago I drove to San Diego and back (210 miles) and it seemed to use maybe even a 1/4 of a tank more. Might be an exaggeration, but it definitely did use more gas. I'm broke right now so I can't afford to go to a mechanic, but I'm looking for ideas on what might be causing it.

thanks

 

[brblx]

if the fuel trim has increased by more than about 20%, you would indeed have a check engine light on.

you can't check fuel mileage by looking at the gauge movement, you have no idea how much gas that is. let it get to a certain point, make a note, and put in a specific amount, like five gallons, then drive until you hit the same mark on the gauge again.

edit- the popping is usually the exhaust cooling. if it's getting especially hot especially quickly, that would actually be more indicative of a lean condition.

 

[CrackRabbit]

I was having a similar problem with my Focus. Turned out to be the rubber hose going from the PCV to the throttle body has gotten a hole in it and was causing the car to run very lean and the computer was trying to compensate by giving it more gas.
Check the rubber hoses going to the throttle body for cracks and holes.
Another idea might be to check the MAF for carbon and dirt buildup.

 

[exdeath]

You would need a scanner to check your fuel trims and see what the O2s are seeing, then determine if the condition causing the imbalance is real or false. Put another way, if it's occurring before or after the combustion chamber.

The spark plugs will tell you if the condition is real or not and where to look. If the fuel trim is high and the spark plugs look reasonable, then it's likely a vacuum leak letting real air in and the computer is doing it's job trying to balance it within it's limited range. If the trim is high and the plugs are black or fuel fouled, it's likely a faulty O2 sensor or exhaust leak and the computer is being mislead to compensate when it doesn't have to.

You can also observe manifold pressure and look for low idle control counts to discover a vacuum leak. You might also perform a fuel pressure leak down test.

If it is in fact running rich as you would confirm with a scanner or sniffer (which would set a light and cause other problems like rough idle and stumbling), my first guess in your case would be an exhaust leak, being that work in that area was done before. If the noises you are hearing are excessive, it indicates lots of expansion and contraction which could easily introduce a leak at an exhaust joint and cause a false O2 output.

 

[exdeath]

So with the above technical stuff out of the way, how about some simpler stuff? Any other symptoms? Is it taking more from your foot to accelerate or is the engine revving more than normal?

Transmission problems or torque converters slipping and not locking can dramatically reduce fuel economy to the extent you are noticing, far more so than fuel trims. I would suspect this is more likely given the extent of your fuel economy reduction and no engine light.

 

[QueBert]

Originally posted by: brblx
if the fuel trim has increased by more than about 20%, you would indeed have a check engine light on.

you can't check fuel mileage by looking at the gauge movement, you have no idea how much gas that is. let it get to a certain point, make a note, and put in a specific amount, like five gallons, then drive until you hit the same mark on the gauge again.

edit- the popping is usually the exhaust cooling. if it's getting especially hot especially quickly, that would actually be more indicative of a lean condition.

I'm wondering why my check engine light isn't coming on, unless the gauge is broke it's definitely sucking up the gas. I drive to SD about twice a month and I know where the gauge is typically at when I get there and when I get back. Last time I had to put in more gas coming back because it was usually low before I got back home. $10 was 3 gallons which is close to a 1/4 a tank. The line right now is where it's at when I'm down to 1.5 gallons or so.

So the popping is it running lean eh? humm, yeah I just drove to the store, about 2 miles away when I got out the car it was very rapid pop-pop-pop, no pause at all between them.

With no check engine light I don't know where to start, hopefully it will come on soon so I can get it diag. There is definitely something up, last week I put in $10, drove maybe 30 miles and the gauge was on E and my gas light was on. Typically $10 will get me about 60 miles before the light comes on 🙁

I'm going to SD soon, it's 99% freeway driving and when I go there's never traffic. I will fill it all the way up and keep a close eye on my gas. I know with freeway driving I should get about 25mpg.

crackrabbit - I will look into both of those, not a car dude at all but I'm sure Googling either will give me plenty of info.

Originally posted by: exdeath
So with the above technical stuff out of the way, how about some simpler stuff? Any other symptoms? Is it taking more from your foot to accelerate or is the engine revving more than normal?

Transmission problems or torque converters slipping and not locking can dramatically reduce fuel economy to the extent you are noticing, far more so than fuel trims. I would suspect this is more likely given the extent of your fuel economy reduction and no engine light.

No, it's accelerating normally, the rpm's aren't jumping around, and it seems to rev normally. At red lights I notice it idles a bit hard, but that might just be me needing a tune up. And it's not so drastic it feels like the cars about to stall, just a lil rough. Driving wise, if I didn't look at the gas gauge, there's nothing that physically feels any different. It's not doing anything out of the ordaniary. All I notice is the excessive popping when I get out of the car, and even 1/2 a mile can result in some pop's. I never paid much attention before, I know cars do this but I never remember it happening after 2 minutes of driving lol.

 

[exdeath]

Originally posted by: QueBert
At red lights I notice it idles a bit hard, but that might just be me needing a tune up. And it's not so drastic it feels like the cars about to stall, just a lil rough. Driving wise, if I didn't look at the gas gauge, there's nothing that physically feels any different. It's not doing anything out of the ordaniary. All I notice is the excessive popping when I get out of the car, and even 1/2 a mile can result in some pop's. I never paid much attention before, I know cars do this but I never remember it happening after 2 minutes of driving lol.

I assume this is in drive? Shift it to neutral when it's doing that and see if it smooths out. And check your transmission fluid level and color just for fun.

 

[QueBert]

Originally posted by: exdeath

Originally posted by: QueBert
At red lights I notice it idles a bit hard, but that might just be me needing a tune up. And it's not so drastic it feels like the cars about to stall, just a lil rough. Driving wise, if I didn't look at the gas gauge, there's nothing that physically feels any different. It's not doing anything out of the ordaniary. All I notice is the excessive popping when I get out of the car, and even 1/2 a mile can result in some pop's. I never paid much attention before, I know cars do this but I never remember it happening after 2 minutes of driving lol.

I assume this is in drive? Shift it to neutral when it's doing that and see if it smooths out. And check your transmission fluid level and color just for fun.

Yes in drive, I will try the neutral thing. I think I might get a tune up and a fluid flush, it's been a long time, and even if it doesn't help it can't hurt. I'm at about 80k I think that's time any ways.

 

[exdeath]

I'm going to go with the torque converter. Going with your numbers using half of $10 (~5 gals at current prices) to go 23 miles is ~9 MPG from a 2000 Taurus. No amount of fuel adjustment is going to cause that.

Doesn't necessarily mean the converter itself. There are numerous parts of the system that determine when and how it should operate, from a dozen sensors and actuators to the fluid itself.

Again with a scanner you could check things like trans fluid temperature and converter status.

Let us know how the drive on the freeway goes with a full tank, that will be a dead giveaway.