Bad gas milage cant figure out why - Third Generation Forum

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Bad gas milage cant figure out why
Monday, February 11, 2013 8:03 PM
Ok 2.2 ohv i have no cat but the o2 sensor is plugged in, It seems to get terrable milage. It also runs 3 ticks under 195 on the coolent temp. I am guessing that it is dumping in a bunch of fuel since i have no cat. I cant seem to find a stock cat for the life of me. Anyone have any ideas.

Re: Bad gas milage cant figure out why
Monday, February 11, 2013 8:09 PM
Why would it be dumping gas........ because there is no cat....
Re: Bad gas milage cant figure out why
Monday, February 11, 2013 9:16 PM
Well i cant find a stock cat cuz they cut them out when the car gets to a junkyard. Would an aftermarket one work. And is that the reason my car is runnig so cool.
Re: Bad gas milage cant figure out why
Tuesday, February 12, 2013 11:15 AM
Sounds to me like your coolant temp sensor is not working, or has a bad connection, which is why you're getting horrible MPG.





i find it amusing that SHOoff has nothing better to do but follow me around & be an unhelpful dick in even cross-forum. - Jon Mick
Re: Bad gas milage cant figure out why
Tuesday, February 12, 2013 6:49 PM
I havent checked that i just figured it was dumping extra fuel and making it run cold.
Re: Bad gas milage cant figure out why
Tuesday, February 12, 2013 9:48 PM
Wes Henning wrote:

I havent checked that i just figured it was dumping extra fuel and making it run cold.


If your coolant temp sensor is bad the car will dump fuel if it thinks it's running way colder than it is. It's also possible the car is dumping fuel because of the O2 sensor getting a crazy reading because it's not getting what it's supposed to without a cat ( this is just speculation, however, but I believe the ECU will make adjustments to fuel based on the O2 sensor feedback ( and not good adjustments)).

I'm gonna go ahead and assume you're getting a check engine light because of having no cat. Get a code reader on that and see if there's another code popping up too.

As long as the catalytic converter you buy is made for OBD-II it will work.



Re: Bad gas milage cant figure out why
Wednesday, February 13, 2013 11:08 AM
It can't be dumping fuel because of a wacky O2 sensor reading from a missing cat. If it's not registering a warm enough coolant temp, then it's not going into closed loop, and thus ignoring any input from the O2 sensor.





i find it amusing that SHOoff has nothing better to do but follow me around & be an unhelpful dick in even cross-forum. - Jon Mick
Re: Bad gas milage cant figure out why
Wednesday, February 13, 2013 11:57 AM
SHOoff wrote:

It can't be dumping fuel because of a wacky O2 sensor reading from a missing cat. If it's not registering a warm enough coolant temp, then it's not going into closed loop, and thus ignoring any input from the O2 sensor.

x2. And in addition unless he has a serious exhaust leak around the manifold or has no exhaust piping after the flex pipe, there's no way the upstream sensor could know something is wrong.


"In Oldskool we trust"
Re: Bad gas milage cant figure out why
Wednesday, February 13, 2013 1:01 PM
I have hooked up a code reader, i havent got anything coolant related, just 02 sensor. Lately it hasnt even had a check engine light on which makes no sense. I just need to get a cat and see if it fixes the problem.
Re: Bad gas milage cant figure out why
Wednesday, February 13, 2013 5:18 PM
No cat and bad gas mileage had nothing to do with each other.

Your 02 code is likely a efficiently code because of no cat and the rear sensor is not reading enough of. Difference from the front sensor. Still will not affect mpgs.

You could research manual 02 simulator to fix that issue, but again will play no affect on mpgs.



FU Tuning



Re: Bad gas milage cant figure out why
Thursday, February 14, 2013 10:24 PM
I recently encountered bad gas mileage with my 2.4. It wasn't ever completely reaching 195* because it had been cold here and I was driving short distances never allowing the engine to reach operating temp. I was getting about 12 mpg city. I have since taken it on a 200 mile round trip all highway and the engine reached operating temp at 195" and It got 28-29 mpg. When the engine doesn't completely reach operating temp, the computer runs in open loop mode and in turn gas mileage suffers because it's running rich.

Re: Bad gas milage cant figure out why
Sunday, February 17, 2013 8:59 AM
Yeah mine usually always reached 195, and even on longer trips it still doesn't
peek above like two ticks down from 195.
Re: Bad gas milage cant figure out why
Sunday, February 17, 2013 10:08 AM
I would look into a thermostat as well. Could be stuck wide open. How long does it take to get engine heat in the morning?


"In Oldskool we trust"
Re: Bad gas milage cant figure out why
Tuesday, February 19, 2013 4:56 PM
update your profile

could it be a cold climate i know canada has been cold as fawk lately then gets warm then cold again but lack of info and lack of accual fuel numbers is hard to tell what an issue is



JBO since July 30, 2001
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