EXCESSIVE fuel consumption while idling!!!

[bigjoncoop]

2007 EXPLORER XLT V6 4.0
175,000 MILES

NORMAL MPG HIGHWAY 15-17 MPG

I noticed since I purchased this Explorer that it burns a TON of gas while idling!

For instance just yesterday I had fallen asleep for about 2 and 1/2 hours and it use over a half a tank of gas!

I live in Central Florida and as you can imagine it is deadly hot during the summer. So while at work during lunch I'll sit in the car with the AC on, etc... so I have always noticed that it burned a ton of fuel while idling...

The engine runs well. I don't smell fuel at all. It's not throwing any error codes that would have anything to do with fuel consumption.

Any ideas? This is nuts

 

[Mbrooks420]

What are the error codes that don’t have to do with fuel consumption?

 

[bigjoncoop]

What are the error codes that don’t have to do with fuel consumption?

The transmission doesn't like going into 3rd gear, unless you feather the gas...
ERROR CODE: P0745

It doesn't have a ruff idle. According to my odb2 is idling at 850-900 RPM.

*** To help explain how much fuel it
consumes while idling...

The day before yesterday on sunday I completely filled the tank. Since then I drove Maybe 50 miles maximum. City driving so maybe used 1/4 of a tank (being generous) I fell asleep for those 2-1/2 hours as I mentioned earlier, and sat in the car for lunch yesterday and today (30min) and my low fuel warning came on, on the way home from work and I just filled it back up now...

Its only like this while idling. If I do not let the car idle for long periods of time and just drive like normal, fuel consumption is fine. It would average approximately 11 miles per gallon in the city or around 15 on the highway. I've owned this for probably 2 years now. It's always been like this...

 

[Mbrooks420]

Have you pulled the plugs? If a fuel injector is sticking it’s usually obvious.

 

[bigjoncoop]

Have you pulled the plugs? If a fuel injector is sticking it’s usually obvious.

No I have not. A few months ago I had to replace my valve cover gaskets and had meant to change the plugs and wires but never got around to it.

So if I pull the plugs it will be noticeable if one of the cylinders has a fuel injector stuck open? I'm assuming the spark plug will be wet with fresh gas?

 

[J_C]

What capacity is your tank and how many gallons are you needing to put in to fill it once the low fuel warning comes on?

What is your normal MPG when it is not left to sit idling?

There is nothing I can think of that would account for excessive fuel loss only while idling so I am posing an alternative theory, that possibly your gas gauge float on the sending unit is sticking so it suddenly drops, possibly in combination with either someone siponing off gas to steal it from you, or someone has access to your vehicle and is taking it for a ride. Have any children with access to the keys? Wife sneaking out in the middle of the night to do X with YZ ?

What I would do next is use a scan tool capable of live data to look at the upstream O2 sensor readings and see if they look similar, or one bank way off because of a stuck injector, and similarly the long term fuel trim. However a stuck open injector would cause poor fuel economy driving as well, just not AS noticeable because you are expecting a higher rate of fuel consumption, so it could just be your fuel level float sticking and the high consumption is not only at idle.

I wouldn't keep running the vehicle if it is wasting that much fuel as it could ruin your cats.

 

[bigjoncoop]

What capacity is your tank and how many gallons are you needing to put in to fill it once the low fuel warning comes on?

Capacity 22.5 gallons

Takes around 20 gallons or so to fill it when the low fuel warning comes on.

What is your normal MPG when it is not left to sit idling?

As I mentioned in the original post I get about 15-17 MPG highway & 10-12 MPG city
(fairly close to factory ratings)

There is nothing I can think of that would account for excessive fuel loss only while idling so I am posing an alternative theory, that possibly your gas gauge float on the sending unit is sticking so it suddenly drops, possibly in combination with either someone siponing off gas to steal it from you, or someone has access to your vehicle and is taking it for a ride. Have any children with access to the keys? Wife sneaking out in the middle of the night to do X with YZ ?

I completely understand where you are coming from. I've had and have known people that's all I had issues that were answered by things like that.

With that said though, that is 100% without a doubt not the cause of the problem. I spend a lot of time in my vehicle due to work and other situations, and since I live in Florida the AC needs to be running 90% of the time.

This is a constant problem that happens in front of my eyes 7 days a week. It's not as if I had a bunch of gas and in the morning on the way to work I notice that half a tank is missing etc...

(This is such a problem that I just built a giant 4 kilowatt battery, and installed it in the back of my explorer with a large inverter and DC to DC charger in order to run a portable AC unit) - Im the DIY battery guy so its no biggie for me but I spend so much money for fuel I needed to do something!!!

NO MORE WIFE , kids grown, and I know for sure that the float is not sticking because of how often I have to put gas in the vehicle.

****
Everyday at work I will let it run for 30 minutes and it'll use an easy 1/8th of a tank.

At least twice a week I will let it run for a hour and a half or so and it will literally drop a quarter of a tank...

Also as I mentioned previously, LAST WEEK I FELL ASLEEP IN THE CAR FOR MAYBE TWO AND A HALF HOURS AND IT USED ABOUT HALF A TANK. I FILLED THE TANK TWICE THAT WEEK AND LITERALLY ONLY DROVE 200 MILES IF THAT!!!

(THIS ALL HAPPENS IN REAL TIME / RIGHT IN FRONT OF MY EYES. CONSISTENTLY... NO EXAGGERATION.

What I would do next is use a scan tool capable of live data to look at the upstream O2 sensor readings and see if they look similar, or one bank way off because of a stuck injector, and similarly the long term fuel trim. However a stuck open injector would cause poor fuel economy driving as well, just not AS noticeable because you are expecting a higher rate of fuel consumption, so it could just be your fuel level float sticking and the high consumption is not only at idle.

I have a OBD2 that can read live data. I just never knew what to look for. Tomorrow I will get a screen recording of the o2 sensor readings and post a reply with the video. I will try to figure out what you mean by a long-term fuel trim, and try to get that for you also ASAP.

I wouldn't keep running the vehicle if it is wasting that much fuel as it could ruin your cats.

I really appreciate you and everyone else's help. I can completely understand how my claims seem crazy, but I can assure you I am a very smart individual with "man hands" and work hard everyday. I've been an electrician for over 25 years and I'm super knowledgeable when it comes to anything technical, and I'm the go-to guy to fix anything technical or someone needs life advise, etc... So I can assure you that this real problem no matter how unlikely it sounds...

But thanks again and I will definitely post that video tomorrow of the o2 sensor readings and get you that fuel trim ASAP

 

[94Eddie]

I have a OBD2 that can read live data. I just never knew what to look for. Tomorrow I will get a screen recording of the o2 sensor readings and post a reply with the video. I will try to figure out what you mean by a long-term fuel trim, and try to get that for you also ASAP.

These two videos might help with understanding fuel trim readings.

 

[bigjoncoop]

What I would do next is use a scan tool capable of live data to look at the upstream O2 sensor readings and see if they look similar, or one bank way off because of a stuck injector, and similarly the long term fuel trim. However a stuck open injector would cause poor fuel economy driving as well, just not AS noticeable because you are expecting a higher rate of fuel consumption, so it could just be your fuel level float sticking and the high consumption is not only at idle.

I just posted a video to YouTube of my OBD2 live data. It shows all the O2 sensor readings as well as all the fuel trim options including short-term and long term.

It shows side by side both driving for 5 minutes and idling for 5 minutes.

*** Updated higher resolution video ***

 

[Motorhogman]

These two videos might help with understanding fuel trim readings.

Great videos.

 

[J_C]

640x360 res and the low 249kbps bitrate is making it so blurry that I can't make out what's what.

 

[bigjoncoop]

640x360 res and the low 249kbps bitrate is making it so blurry that I can't make out what's what.

DAMN! Thx for letting me know. I don't know why the video exported like that. I will re-upload better version now.

 

[bigjoncoop]

Here is the updated higher resolution video of o2 sensor readings, Fuel trims, etc..

 

[J_C]

Okay I'm looking at your new video, still hard to see but I've enhanced it and noticed a few things so far.

- Idle is high at 850-900 RPM
- IAT temp reporting high at 173F
- Bank 2 Long Term Fuel Trim perpetually reading a bit high but not severely so. Seems stuck at 9.38. I'd try clearing PCM volatile memory (disconnect battery for a minute).
- The listed consumption rate of 0.83 gal/hr idling seems high, but is nowhere near as high as you're suggesting it really is.

I'll look a bit longer but so far, I don't know. Have you ever cleaned your MAF sensor, or cleaned or replaced the IAC valve? If those check out then I suspect a minor vac leak (possibly intake manifold) but that also, along with this real time data, does not support the very high fuel consumption rate you're suggesting.

If the fuel isn't leaking out onto the ground, it has to be coming out the tailpipe either burnt or unburnt and you don't mention any evidence of either of these things happening. If you have the means, something else to check after a few minutes running is the temperature of the cats... or if they're glowing orange/red, shut it down.

 

[94Eddie]

It seems like there is unmetered air entering the engine and the computer is using fuel adjustment based on O2 readings to keep the AFR within specs. Maybe this is an inefficient way meter fuel and causes excess fuel use? Another reason I think there might be unmetered air entering the system is that the LTFT evens out to a more reasonable number when driving. During driving the increased air intake makes a small leak less of an impact on A/F numbers. Whether this might be causing the idle fuel consumption is, I can't say.

 

[bigjoncoop]

I'd try clearing PCM volatile memory (disconnect battery for a minute).

I've done that not too long ago but I will do that again for sure.

Have you ever cleaned your MAF sensor, or cleaned or replaced the IAC valve?

I have not. I will that ASAP

If the fuel isn't leaking out onto the ground, it has to be coming out the tailpipe either burnt or unburnt and you don't mention any evidence of either of these things happening.

Funny you mention that. I always have a ton of liquid dripping out of the tailpipe excessively. For instance normally the puddle underneath the exhaust is as big or bigger than the condensation puddle dripping from the AC. And I live in Central Florida so it is super humid here.
I was concerned when I initially noticed it a while back so I looked it up, and I read that that is common that it's just water vapor... It that true? I haven't smelled the liquid itself, but I don't notice any fuel smell at all. Hmm...

If you have the means, something else to check after a few minutes running is the temperature of the cats... or if they're glowing orange/red, shut it down.

I will use my temp gun and see what they measure. I will report back all my findings ASAP.

Thanks again for you help!!!

It seems like there is unmetered air entering the engine and the computer is using fuel adjustment based on O2 readings to keep the AFR within specs. During driving the increased air intake makes a small leak less of an impact on A/F numbers.

Is there a good / cheap way of checking for vacuum leaks?

Thx

 

[bigjoncoop]

Just wanted post a most recent update on this incredible high fuel consumption!!!

Last night after work I pulled into Walmart's parking lot and accidentally fell asleep for about 3hrs with the engine running with the AC on and I had just about 5/8 of a tank and woke up with the needle past E, and remaining miles at 0!!!

Also right now as I'm writing this and my responses to the previous posts, I've dropped a easy 1/8 tank in approximately 15-20 minutes!

OMG this is crazy

*I just ordered plugs and wires. I figured if I'm going to pull all the plugs and look at them I might as well replace them the same time.

 

[Mbrooks420]

You might want to check that pig for carbon monoxide if you’re accidentally falling asleep for hours on a regular basis.

Your sleeping gas usage would make another car payment.

 

[94Eddie]

Definitely get yourself a carbon monoxide monitor. When I was in high school a couple fell asleep in a running car they were parking in during the winter months. The wind was blowing in just the right way to let the exhaust enter the car. They both died from carbon monoxide poisoning. Battery powered carbon monoxide detectors are inexpensive so you don't have to put yourself at risk.