hello.96 850..87k . i am getting crap gass milage, around 11mpg city. i pulled a plug and it was a little browner that i like. also it was wet with gass. this tells me that the o2 sensors are shot, but i have no check engine light. i replaced all the vacuum lines and put a bottle of the cat cleaner in. any one else have any ideas of what to do. also is there a emitions thingy that puts air down the exhaust. if so could this effect gass milage.
thanks

 

Do you mean EGR?
Your might have it you would have to look.
The mass flow or coolant temp sensor could also be bad causing the same thing.

 

the egr looks new. a maf usually doesn't give a false reading, it just breaks. the coolant temp could be bad, if so how do i diagnose it.

 

Usually by reading the temps from OBDII.
A mass flow can give the false readings I see it all the time and it doesn't always throw codes.

 

the only time i had a maf go bad is when i sucked water up a cai and it broke the hot wire. however, if you are correct, what values do i look for in the obdII code reader. i am assuming that it will give you values, but i have only use them to pull and erase codes. also if it is the head temp sensor, what values should i look for.
thanks

 

incorrect. maf sensors CAN and DO give false readings, causing your car to sputter/hesitate without reason or cause...my Lincoln town car had this problem. R&R'ed MAF and check engine light never came back on and car purrs again.

 

If your OBDII reads it see that the temp about matches the coolant temp.
Looking al the mass flow correction value I believe it should be like 3 volts.

 

I too believe you are on the right track checking the MAF and the coolant temp sensor. However, when our coolant temperature sensor went bad, it threw a code (1-2-3) and the check engine light came on.

When you say you have no check engine light, are you sure the light is not burned out (i.e. comes on when you first start the car) I know it is a long shot, but it IS a light bulb and I have seen them go out.

Good luck

 

Mine was on so much that it burnt out. When I had the intrument cluster out I switched the Service light to the CEL spot. Now I never have to look at the Service light again, and of course the CEL is always on.

 

the bulb is ok. it turns on when the key is in the #1 position. i put a can of "solder" in the tank. its boasts to clean the cat and o2 sensor the rotten egg smell went away, and alot of water now comes out the tail pipe. will let you all know what happens.

 

i rented a obdII code reader from auto zone today. unfortunately it didnt give me valueson the sensor voltage. what kind of obd reader do i need. the auto zone is a actron. also i can read the o2 for error but they never got upto temp after 15 minuted of driving and 40 min of idle. any ideas

 

Actron should make a model that will give real time values.

 

ive got a scan gage II in my subaru will that work. the subaru has a map not a maf. will the maf be displayed in volts? the map is in bars

 

Not sure the only way to know for sure is to try it.

 

FYR.


JPN

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