My car is swallowing gas all of a sudden!

I usually notice a drop in gas mileage this time of year due to the winter blend of gas, but I have gone from averaging 18-20 around town driving it gingerly, to about 10 - 12!

My cold air FWI wouldn't have something to do with it now that it is colder outside would it?
Doesn't make sense to me that it would, but seem to recall that being mentioned in a thread here once.
I've bought gas at a couple of different stations and different brands too.
Always 92 octane.

I may run over to Autozone and have them pull codes. Can't hurt.

Really hurts the pocket book

that sounds weird. i guess youve allready done all the obvious, clean the,AIC ,throttle body,maf, etc,etc. injectors not clogged,i dont know how to check that though? have you checked that the E-brake is disengaged?

robotennis61 wrote:

that sounds weird. i guess youve allready done all the obvious, clean the,AIC ,throttle body,maf, etc,etc. injectors not clogged,i dont know how to check that though? have you checked that the E-brake is disengaged?

E-brake doesn't even work. Did you mean the IAC, or IAT sensor?
I was thinking of pulling the MAF and throttle body and clean them. I still have a can each of the proper cleaners. I last did both in the spring.
Maybe a can of injector cleaner is in order too.

yes. i dont know much about elec systems but cleaning those components allways smooths out the engines performance for me providing all sensors and what not are operating optimally. the idle air control valve gets really dirty,and from what ive learned,i coud be wrong, can contribute to a multitude of drivability issues,so too the MAF sensor and throttle body.i imagine components taking a bigger beating out where you live with the cold winters. clean your EGR valve too.cant hurt. my BCS is taking a crap on me,if its faulty maybe it can cause the car to consume more? at least i have noticed less mileage since it started to act up. who knows? wish i knew more about these things.

Sweepspear wrote:

robotennis61 wrote:

that sounds weird. i guess youve allready done all the obvious, clean the,AIC ,throttle body,maf, etc,etc. injectors not clogged,i dont know how to check that though? have you checked that the E-brake is disengaged?

E-brake doesn't even work. Did you mean the IAC, or IAT sensor?
I was thinking of pulling the MAF and throttle body and clean them. I still have a can each of the proper cleaners. I last did both in the spring.
Maybe a can of injector cleaner is in order too.

Have you ever read the oxygen sensor with a scope to see if it is putting out full signal. If signal is weak car wil run a bit rich.

Also pay attention to how the transmission is shifting.

Albertj

robotennis61 wrote:

yes. i dont know much about elec systems but cleaning those components allways smooths out the engines performance for me providing all sensors and what not are operating optimally. the idle air control valve gets really dirty,and from what ive learned,i coud be wrong, can contribute to a multitude of drivability issues,so too the MAF sensor and throttle body.i imagine components taking a bigger beating out where you live with the cold winters. clean your EGR valve too.cant hurt. my BCS is taking a crap on me,if its faulty maybe it can cause the car to consume more? at least i have noticed less mileage since it started to act up. who knows? wish i knew more about these things.

What is the "BCS"

I hate these abbreviations and Acronyms. You have to have some kind of special powers to figure out everybody's different terms, sometimes for the same thing

Sweepspear wrote:

I usually notice a drop in gas mileage this time of year due to the winter blend of gas, but I have gone from averaging 18-20 around town driving it gingerly, to about 10 - 12!

My cold air FWI wouldn't have something to do with it now that it is colder outside would it?
Doesn't make sense to me that it would, but seem to recall that being mentioned in a thread here once.
I've bought gas at a couple of different stations and different brands too.
Always 92 octane.

I may run over to Autozone and have them pull codes. Can't hurt.

Really hurts the pocket book

If there is no "Check Engine Light" then any stored codes will not and should not effect driveability or gas mileage.
Any component that goes bad that would cause this issue would trip a light. Anything that is emissions and driveability related trips the light.

How come you still have to go to the Auto Parts store and have them check your car for hidden codes.?

An approximate 50% drop in fuel mileage is severe as far as I'm concerned.

O2 sensor, MAF, air filter, fuel filter... for starters. My car has been sipping more gas but I think that has to do with the 18s. going to replace the O2 anyway. couldn't hurt

Rick, even a lazy O2 will trip the light. That happens long before a failure of the sensor.
You have to be able to watch the operation of the O2 sensor, preferable in a graphing mode, and then you can see the lazy operation of the sensor.
A lazy sensor will not cause an extreme change in fuel economy though, I have experienced it before and lucky enough to have a Tech down the road with a Snap-On diagnostic graphing scanner. What that means is you can watch these various sensors in real time as they plot a graph for you and you can see how they operate during different throttle maneuvers or just at idle, etc.
Any of the other tuning software will pick it up as well, such as HPT and DHP.

I don't like replacing parts unless I can test them and determine they are actually bad. Replacing parts "Just Because" is too wasteful and doesn't get you any closer to finding the real problem, not to mention that one of the replacement parts can be bad out of the box, new, and really screw you up. I had that happen with 3 oxygen sensors in a row.
The guy at the parts store would have been very apprehensive taking all these sensors back and tagging them as bad had it not been the reputation of the people and test equipment involved.

An air leak after the MAF will make run lean, then based on lean O2 readings, the PCM will correct by adding more fuel. This could be one cause for it.

Alternatively, have you been filling up with E-15 or E-20 instead of E-10? E-85? This will also cause you to use more fuel. I recently heard they are contemplating regulations forcing the change from E-10 to E-15 in our area.

In my case I'm just replacing it because it's never been touched and I've seen improvements in mpg on past cars from just changing an old O2 with a fresh one. I consider it routine maintenance that should be done after 100K miles (plugs, wires, fuel filter, air filter, etc). The Regal's mpg went up considerably (not drastic but enough to justify) when I changed over to a Denso. It also helped eliminate KR when the car was stock. I've seen O2 sensors get old and not read as accurately without tripping codes.

Rickw wrote:

Rick, even a lazy O2 will trip the light. That happens long before a failure of the sensor.
You have to be able to watch the operation of the O2 sensor, preferable in a graphing mode, and then you can see the lazy operation of the sensor.
A lazy sensor will not cause an extreme change in fuel economy though, I have experienced it before and lucky enough to have a Tech down the road with a Snap-On diagnostic graphing scanner. What that means is you can watch these various sensors in real time as they plot a graph for you and you can see how they operate during different throttle maneuvers or just at idle, etc.
Any of the other tuning software will pick it up as well, such as HPT and DHP.

I don't like replacing parts unless I can test them and determine they are actually bad. Replacing parts "Just Because" is too wasteful and doesn't get you any closer to finding the real problem, not to mention that one of the replacement parts can be bad out of the box, new, and really screw you up. I had that happen with 3 oxygen sensors in a row.
The guy at the parts store would have been very apprehensive taking all these sensors back and tagging them as bad had it not been the reputation of the people and test equipment involved.

agreed.

still wanna know if you scoped the o2.

DEMonte1997 wrote:

In my case I'm just replacing it because it's never been touched and I've seen improvements in mpg on past cars from just changing an old O2 with a fresh one. I consider it routine maintenance that should be done after 100K miles (plugs, wires, fuel filter, air filter, etc). The Regal's mpg went up considerably (not drastic but enough to justify) when I changed over to a Denso. It also helped eliminate KR when the car was stock. I've seen O2 sensors get old and not read as accurately without tripping codes.

Actually, this depends also on when you had your car dealer serviced. There is a TSB (don't know number) to flash the PCM to compensate for aging o2 sensors. Although weakening, the OE o2 sensor can last a *very* long time if you never misfuel the car or use additives over time.

Albertj

deekster_caddy wrote:

An air leak after the MAF will make run lean, then based on lean O2 readings, the PCM will correct by adding more fuel. This could be one cause for it.

Alternatively, have you been filling up with E-15 or E-20 instead of E-10? E-85? This will also cause you to use more fuel. I recently heard they are contemplating regulations forcing the change from E-10 to E-15 in our area.

The Gov't is still talking about the mandating of E15, not just for New England and a select few other areas of the country but this time it will be 49 State wide. It is still being discussed and studied, but you can bet as soon as they get through whatever hurdles they have to it will be LAW.
I say 49 state's because CA has there own special arrangements that are sanctioned by the Energy Dept and the EPA. So they get to screw their residents as they see fit and make laws that affect all the cars manufacturers, thus affecting all the states by the "Technology" they force on the car Mfg's.

BCS = boost control solenoid.
...........and WTF do i know?

albertj wrote:

DEMonte1997 wrote:

In my case I'm just replacing it because it's never been touched and I've seen improvements in mpg on past cars from just changing an old O2 with a fresh one. I consider it routine maintenance that should be done after 100K miles (plugs, wires, fuel filter, air filter, etc). The Regal's mpg went up considerably (not drastic but enough to justify) when I changed over to a Denso. It also helped eliminate KR when the car was stock. I've seen O2 sensors get old and not read as accurately without tripping codes.

Actually, this depends also on when you had your car dealer serviced. There is a TSB (don't know number) to flash the PCM to compensate for aging o2 sensors. Although weakening, the OE o2 sensor can last a *very* long time if you never misfuel the car or use additives over time.

Albertj

dealer and service aren't part of my vocabulary. just kidding... well not really. i wasn't aware of this TSB.. interesting. now that i have the powrtuner i can just scan and write to modify tables as necessary.

Quote :

There is a TSB (don't know number) to flash the PCM to compensate for aging o2 sensors. Although weakening, the OE o2 sensor can last a *very* long time if you never misfuel the car or use additives over time.

I strongly disagree with this type of "fix", unless it could be shown that installing a brand new O2 sensor, along with the flash compensation, would not compromise performance. If this were the case, it means the tune was wrong from the beginning, but I would think compensating for a bad O2 with flash tune would not give the best results.

This has to be it.
My Boost Bypass pulled the valve past center, and it got hung up in the open position. (or closed position. whatever.)
I adjusted the the canister just a little bit lower so it can't do this again.
It was about a week ago that I flogged it through the gears a couple times.
That's when it got hung up I bet.

To answer other's questions, I don't own an OBDII scan tool. I know, I know, It's one of those tools that has been on my list forever, but for one reason or another just haven't got around to buying. I also haven't been willing to buy a cheap one.
I suppose I could get the codes manually counting flashes of the Service Engine light but I hate doing it that way.
When I bought the car, I went through and replaced the 02 sensors at the same time I did plugs, wires, filters, etc. So, while there are no guarantees, odds are after less than 10,000 miles they are probably still ok.

Thanks for the replys!

^^ I'm not exactly sure I understand what you are saying. When I first bought the Regal some people were saying that you could adjust the boost bypass solenoid by loosening the three nuts that hold it in place. By putting it all the way down, you would build boost quicker so the car would be a lot more torquey around town. But that also meant you risked possibly getting burst knock if you romped on it quickly. Is this the same thing you are talking about?

In any event, I hope this was your issue and it's all fixed now.