I'm getting 9 MPG in the city no matter the driving style. I really think there's something that is causing this, maybe you guys can help.
To give you some background about the car, it's a 2007 Crossfire Limited Automatic NA.

New air filters, new sparkplugs, new fuel filter.
The mass airflow sensor got cleaned.
New tires, wheel alignment, etc.

Everything seems fine, the car behaves normal.
From all the research I did, what's left would be the injectors or the oxygen sensor, I didn't change those.

Let me know what you guys think and if you experieced something like this.

 

How long have you had the car and was it always this bad?

 

It was always like this

 

Are you miscalculating Liters vice Gallons?? Here in the USA measuring gallons with a Crossfire Limited we get about 30 miles to a gallon driving on open highways and about 28 MPG in the city. If you brake that down in a conversions to liters 30 / 3.7854 = 7.925 and 28 / 3.7854 = 7.4 Plus your distance is measured kilometers vice miles.
I do not think a Crossfire would even run on mileage that you are getting unless the fuel was leaking out of the system, because the engine fuel ratio would be too too rich for ignition.

 

I did the conversion. 26 l/100 km or 9mpg
The fuel tank and fuel lines are all fine, no fuel leaks.

 

Pull the oil dipstick out and sniff it to see if you have fuel in the oil. Do this away from cars/gas cans, so you get a cleaner odor of fuel (if present). Then check the exhaust while the engine is running, if your actually burning it, your tailpipe will be very soot filled and the exhaust will have a raw gas smell. One more thing, while it is running pop off the oil filler cap, the engine rpm's should change. Come back and post the results. Good luck.


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THis just barely makes sense. If I drive the SE the hardest I can, thru the Dragon and other roads all day, I get, at the very lowest, around 12-13. I know this cause I refill every day when I'm up there.
If you drive it reasonably, I"d expect 20-22 in town, I know I get about that (hard to say cause I mix town/country driving so much and I usually get around 25).

How could the car be running THAT rich and not show signs of rough idle and lowered performance (that is, lower acceleration, etc.) with that much more fuel going into the engine.

What is the fuel pressure like? I would never proceed too far with a fuel system / fuel consumption issue without knowing the fuel pressure. The ECU assumes 55-60psi. But there is no sensor telling the ECU what the pressure is, it simply opens the injectors for the amount of time that would be correct, based on correct fuel pressure. With low or high pressure, you will get lower or higher fuel/air ratios. Therefore, if you do not know the fuel pressure, you don't know what the engine is getting, the O2 sensors only measure the amount of oxygen in the exhaust, not the amount of unburnt fuel, nor any direct measure of other emissions in the tailpipe.

I've had two instances of incorrect fuel pressure in injected engines, the symptoms made no sense, until I put a pressure test kit on it, then suddenly I knew what I had - bad fuel pump/filter/regulator/fuel pickup.

 

I would do a good compression test which could indicate if there are some valve related issues. The recommendation to check the fuel pressure is a good one. Pull some of the spark plugs and check for the presence of black soot or wetness. It is possible the coils are underperforming in terms of their discharge energy and need to be replaced. I did this on my 3.5L Benz and it made a measurable differenence in fuel consumption and engine performance. Maybe the resistance of sparkplug wires is excessive and need to be replaced. This thought might be on the crazy side but could the odometer be faulty?

 

WOW. I missed that.

I have OFTEN said, "Anyone changing plugs on a 15 year old car and not also changing the plug wires is making a mistake".
Personally, twice, I changed plugs (on other vehicles) and made things WORSE because the act of wrestling the plug wires off and back on was enough to injure at least one of them.

I made a new rule: "If the engine needs plugs, it needs wires as well".

As to the odometer, the data that drives the odometer is the same data that drives the speedometer. This data comes from the ABS controller and I'd bet (don't really know) that the same mini-module in the cluster drives the speedometer and odometer. Since the speedo is correct, the only way the odometer would likely be off is if the time base for each function was different and the one for the odometer was off. But I doubt there is a separate time base for the two functions. As nutty as it all sounds, I'd bet he really IS getting 9mpg. But You'd think his plugs (and even exahust tips) would show it, as you have indicated.

 

I just dont see how it is possible to get that bad of gas mileage on a crossfire. It would have to run like total crap, I think your conversion math is off. Even my modded srt6 would avg 19mpg.

Now my Ram SRT-10, that thing got 9 mpg mo matter what you did but that was a 5200 pound 6 speed truck with a 8.3 liter viper v10. You could see the gas gauge moving down if it idle for a long time, haha.

 

Pizza guy in regard to the input pulses or data points to the odometer, is this data generated by an optical encoder driven somewhere off the transmission output shaft? If it is and it is operating erratically this could be affecting the distance data input to the odometer. If 9mpg is real where is all the fuel going? It almost seems like the exhaust system should be operating like an after burner on a gas turbine engine.

 

No, that whole thing about driving a speedometer by a sensor/cable on the output of the transmission is "old school", not "R170" at all.

There is a wheel speed sensor at each wheel. All four of them report to the CAB (Controller-Antilock Brake), that is, the brake controller. The CAB then sends front wheel speed sensor data only to the Instrument cluster on CAN BUS C, the cluster then uses this data to drive the speedometer and odometer. (The data is also sent to the TCU [automatics only] and PCM/ECM, but not for the purpose we are talking about here.) If the speedometer is accurate, the data is accurate.

I agree, 9mpg sounds nuts, but again, I have seen my SE go down into the 12-14mpg range when driven hard on, say, the Dragon (hey, it takes a lot to keep up with SRTs!) It just seems to me, as has been mentioned before, the plugs and exhaust tips should show a lot of carbon buildup.

 

Thanks to everyone for answering and trying to help.
I will answer some questions:

- No gas in the oil
- No raw gas smell coming from the exhaust

Recently I did a trip outside of the city and I averaged 23MPG which is decent. But you guys are getting that in the city so yea...

I will try to replace the o2 engine sensors and the one in the exhaust, new injectors and sparkplug wires.

 

I'm just curious, have you scanned for codes?

 

Yes, quite recently after I did the servicing, and no faulty codes.
The only thing that I can't find a fix for is the BAS/ESP light, but I don't think that's related in any way.

 

In the past I have seen plugged or clogged catalytic converters cause bad gas mileage. I would take a look at the entire exhaust system just to be sure..

 

When I say "In town", I am driving at least 1/2 the time on a Texas highway at speeds of 60+.
I do wonder if I really would get 20mpg actually driving in town under 40mph most of the time.

That is to say, I hope I am not misleading you.

 

Is it possible that the calibration of the pump meter wherever you're filling up, is short changing you? Or perhaps someone is siphoning(stealing) gas from your tank?