High fuel consumption

[bobcat-kindly]

My 2007 Buick Allure CX 3.8L V6 is consuming too much fuel (23-24L/100KM) and I have no idea why as I have already got replaced a lot of parts including new water pump, spark plugs, crankshaft position sensor but issue is still there.. the shop I take it to and another one also is also not able to pinpoint what could be wrong with it and both said it is running fine and honestly it is running fine but consuming high amount of fuel while at stop or idling but it consumes less when it is running on the road. I will greatly appreciate any help regarding this. Please feel free to ask me any information I might have not added here that may help you in determining what could be the issue here

 

[ulycyc]

Depends on how long you idle per tank of fuel. The standard average is roughly 1/2 gal per hour. Also more if your AC and extra accessories on on. Stuck in a traffic jam for 2 hours and easily use a few gals of gas. Your results could be normal.

 

[bobcat-kindly]

Depends on how long you idle per tank of fuel. The standard average is roughly 1/2 gal per hour. Also more if your AC and extra accessories on on. Stuck in a traffic jam for 2 hours and easily use a few gals of gas. Your results could be normal.

Hi,

I really think it's consuming more than the normal amount, is there any way to know for sure like with a scan tool or something and what should I look for?

Thanks

 

[richardnewton]

You can look at short- and long-term fuel trims. And 02 sensor performance. Also look for vacuum leaks.

Check intake and exhaust for leaks too.

Is the air filter new? Can you clean the MAF sensor, EGR sensor/pipes?

 

[bobcat-kindly]

You can look at short- and long-term fuel trims. And 02 sensor performance. Also look for vacuum leaks.

Check intake and exhaust for leaks too.

Is the air filter new? Can you clean the MAF sensor, EGR sensor/pipes?

Hi, I forgot to mention it has new MAF sensor also. I scanned my car but I am not sure if the readings for the short and long term fuel trims is normal or not , also I am not sure how to check for vacuum leaks or how to clean the egr sensor or pipes

 

[richardnewton]

Was the original MAF OEM? Was it failing? Is the new MAF OEM? These engines are very sensitive to OEM electronics IME; so if you don't have an OEM MAF, that is the first stop IMHO.

As the car warms up, the front o2 sensors typically oscillate and the rears should stabilize.

These videos should give you a primer on fuel trims, which can be very helpful for diagnosis.

 

[bobcat-kindly]

Was the original MAF OEM? Was it failing? Is the new MAF OEM? These engines are very sensitive to OEM electronics IME; so if you don't have an OEM MAF, that is the first stop IMHO.

As the car warms up, the front o2 sensors typically oscillate and the rears should stabilize.

These videos should give you a primer on fuel trims, which can be very helpful for diagnosis.

Thanks I will watch the videos and get back to you if I have any questions

 

[bobcat-kindly]

So, today I filled up the tank (with 87 regular fuel) and idled the car for 1 hour in the parking lot of that fuel pump with the heat on full blast and I filled up the tank again after 1 hour and I found it consumed 3.7 litres of fuel within that 1 hour .. so is it normal?

I suspect its very high but I could be wrong also ... please help

 

[ulycyc]

As I said earlier that falls with-in average consumption for one hour. Maybe a little on the higher side of the average. Your talking about very small amount. How you filled it up could be the difference. Did you fill it both time so you can see fuel at the top of the neck ready to drip out? The nozzle auto cut off point is not absolute.