BIG gasmilage loss..please help

[WannaXP8]

I have a 98 5.0 awd, and its getting like no gas milage, I mean last night i filled up, and drove like 70 miles and i used a half tank of gas. I have mac exhaust, and a kkm, and I put a 180 thermo in it, and I have 31s, but its never been that bad on gas before, whats up..I mean I dont drive it that much cause I have a prerunner ranger I drive alot..but I need gas milage out of it, cause I drive this on my long distance trips...

 

[CDW6212R]

How long have you had the 31's on it? Those heavier wheels/tires are costing you a bunch of MPG.
You know that you are going farther than the odometer reads, yes? Calculate your MPG change just from your diameter change, by multiplying by 29/31. LOL,
Don

 

[Ryan1]

have you o2 sensors checked.

Ryan

 

[aldive]

That 180 F thermostat is costing you mileage too.

 

[svande8952]

180 tstat=less MPG? How?

 

[aldive]

180 tstat=less MPG? How?

The trucks computer is designed to functional optimally with the 190-195 F thermostat. Changing the t stat to a lower temp one confuses the readings and wastes fuel ( unless it has a chip.program designed for 180 F ).

 

[00XLS]

The trucks computer is designed to functional optimally with the 190-195 F thermostat. Changing the t stat to a lower temp one confuses the readings and wastes fuel ( unless it has a chip.program designed for 180 F ).

I concur, the lower tstat and bigger tires is probably enough to do it. You engine is sucking more and more fuel trying to reach 195* along with a larger tire that its not recognizing.

 

[WannaXP8]

well I have had the 31s on it for about 2 years now, but just changed to the 180 thermo about 2 months ago..

 

[Eneurb]

If you used half a tank of fuel in 70 miles, I would expect to see fuel pouring out of the tail pipe!!! With that kind of fuel mileage, you must have some type of driveablility or leakage symptom to go with it.

 

[IAmTodd]

I have run 31s on mine for the past few months and have recieved about 13mpg. From monitoring my coolant temp, it doesn't go above 185ish degrees. On warmer days it will, but the cold weather won't let it. So I assume thats why me and you are recieving poor mileage.

 

[metstalker]

just incase your wondering you lose 1/10 of a mile from stock to 31s i figured this out a couple days ago..... just letting you know if case you were wondering

 

[IAmTodd]

I'm actually getting better than what the odometer says I am since it going with unnoticed miles, But I'm not real concerned. Sometime its at the dealer I'll see if they can reprogram it for 30 inch tires.

 

[svande8952]

I concur, the lower tstat and bigger tires is probably enough to do it. You engine is sucking more and more fuel trying to reach 195*

I don't know about that. The computer usually monitors and regulates fuel flow with EGT and CHT, not water temp. Am I missing something?

 

[philipb123]

I bought some chrome rims, 22" with some Toyo Proxes S/T 305/40/22. Since they weigh more etc..., will I be loosing a lot of mileage? And if I take my X to the dealer can they reprogram my computer to show the right MPH on my speedo?

 

[IAmTodd]

I bought some chrome rims, 22" with some Toyo Proxes S/T 305/40/22. Since they weigh more etc..., will I be loosing a lot of mileage? And if I take my X to the dealer can they reprogram my computer to show the right MPH on my speedo?

Yes, they can correct the PCM for the different size tires. If you have it in for service sometime mention it to them. They might do it for free. They did it to our '02 when we put 245/75s on it.

 

[IAmTodd]

I don't know about that. The computer usually monitors and regulates fuel flow with EGT and CHT, not water temp. Am I missing something?

I don't know what CHT is. But Expos don't have EGT sensors, so it can't really go by that. I do remember Al(think it was him) was having problems with his, and changing a bad thermostat corrected it. I think it was idling high, hence the motor was trying to warm itself up. I do think coolant temp has a lot to do on how the motor runs.

 

[philipb123]

Well I'm gonna take it there to mount the rims so I'll just tell them then. These tires will fit right? I know the rims will but I went to Discount Tires website to see what tires fit the X, and this particular size of 22's didn't come up?