My 93 850 is still getting bad mpg!!! So far I have replaced the fuel pressure regulator (it was bad Thanks to who told me check it!! it starts good now). The 02 sensor was replaced, although it is still throwing a code for it wtf???? it also says the idle control is bad(it maybe as it idles low sometimes) but that should have nothing to do with it right?. It gets 20mpg no matter what. Was getting 27-29. It all seemed to start when it got cold. So maybe temp issue?? Computer telling itself cold start more fuel??? all the time?? Thanks In advance IAP P.S it does smell a bit rich O2 not hooked up right??

 

Cars get worse mpg when it's cold. Thinner cold air. But shouldn't be that bad. Check and make sure you don't have a brake dragging. Have you done a stage 0?

 

If you smell fuel, you likely have a vac line loose somewhere.

 

My winter daily driver was worse than 20 MPG's when the temps dropped. Discovered all 4 tires needed air and the ATF level was down. Correcting those restored my winter time MPG.

 

cold air is actually more dense than warm air. more air = more fuel, hence the drop in mileage.

 

+1

Your mileage will always go down in the winter. Mine went down 2 - 3 miles per gallon.

 

What codes did you pull?

 

Sorry new to this.... What is a stage 0?? The code numbers.. i forgot a 7 i think... but.. I had it checked at local import shop THEY WERE NO HELP they would not give me the time of day. Seems i should have left it there at $60 an hour!!!! So he could fidle with it.. They didnt even know how to read the codes. And they didnt clear them. 35 bucks up in smoke!!! By bad smell i mean the exaust It smells rich. No vac leaks that i know of. Also The air box door is always open it dont work. Cold air all the time no pre warmed. So no temp sensor issue?? As for codes i gather that you can do this your self How?? Is there a plugin for a reader as well as the light?( a friend has a obd1 reader) Thanks Again IAP

 

AutoZone= free codes and reset

 

I don't think AZ could read pre-OBDII codes. You should be able to read codes (light-flashes) at the terminal (right front, engine compartment). Check the stickies here for how...

 

Also, not all AutoZones will check the codes for you anymore. I know in NJ, a lot of them say they can't now.

 

a bad thermostat will affect fuel mileage. might want to check into that. also check the water temp sensor right there also.

 

Yep chekin it soon... It also possibly over fueling as i changed the oil and it smelled like gas..... A week later the new oil smells like gas. No smoke. LOTS of carbon in the intake area(i think) had the injectors out... looked grim!!! Thanks IAP

 

I Liked your answer to this concerning the air temp. A really good answer is aircraft flight theory. As it gets colder, it is easier to take off. Anyway, I have a 94 turbo 850 with both the Engine diagnostic A&B and the console OBDII. Wonder why all Volvo's don't have this. It helps to determine if the fault is real.

pgu44