So I did the ECU temp sensor swap in hopes of getting better gas mileage. I bought an after market sensor from the local parts store and now my 97 is getting worse gas mileage. I reset the ECU by disconnecting the neg batt cable for 20min. Is there an adaption period for the ECU or could the after market part not be as sufficient as an OEM part? thanks for the help guys!

 

same thing happened to me and i just got these answers:
Change the o2 sensors down by the cats, of course i haven't change them. I am going nuts because is giving me about 13-15mpg combined highway and city. I dont know what to do..

 

I actually thought about the O2 sensors today, but why would they go bad instantaneously when changing a temp sensor is beyond me. Did you swap yours with an OEM part or after market?

 

YES, IT WAS OEM. I GOT IT FROM WORLDPAC, A OE PARTS DISTRIBUTOR HERE IN CENTRAL FLORIDA. I' VE DONE CAPS/ROTORS/SPARK PLUGS AIR AND FUEL FILTER AND IT DID GOOD ABOUT 17MPG BUT IT WENT DOWN AGAIN...

 

dang man. I was getting 18-21 consistently, changed it out and the next day went to like 15-17. I am almost tempted to buy a Lexus part but its hard to believe that such a simple part would have that much discrepancy..

 

I'VE NEVER GOTTEN PASS 17MPG'S. I READ ABOUT 21+MPG AND I SAY WAO. BUT I DONT KNOW REALLY WHAT THE HECK TO DO.

 

no need to shout, mpg is all relative to driving style what gas you use and even tire pressure

 

true that, I am a grandpa behind the wheel in these austin hills. the only thing that changed other than the temp sensor is some pretty hot *** weather for this time of year.

 

I drive 8 miles a day round trip and I rarely drive on highways and drive like a old man. The tire pressure is at best and the only thing to change are the O2 sensors and what else, the car has 91k miles right now...

 

8 miles a day, and you're worried about fuel mileage? That's about a tank every month and a half. 17 MPG isn't bad at all for all city driving. I get about 12 MPG now b/c the car needs to warm up with this cold weather, but I don't mind b/c I drive even less then you. Last week I drove 16.7 miles, $5.

 

the hot weather could be a large factor tbh

 

thought i chime in cus after i changed ect sensor, new thermostat, pcv, and with lil below half tank, i clocked in 224 miles. which means average of 20.3 mpg. before that it was getting about 170 miles a half tank. now with 32 oz of lucas fuel injector cleaner in the tank, hope to increase it bit more.

 

Do you have CEL light on?
i recommend you to scan your car and post oxygen sensors readings on idle.

 

You better diagnose the parts before buying new parts!!

 

I changed mine last week with an aftermarket one I purchased at Autozone. I don't remember the brand. I live in Odessa,Tx and had a trip to El Paso which is about 286 miles. I only make a stop in Van Horn for gas. When I left I had 3/4 tank and 80-20 city/hwy driving on it. I got 22.11mpg. On the return trip I filled up and drove to Van Horn where I filled up again even though I only used a 1/4 tank and got 31.3mpg. This is driving mostly 65 miles per hour because I was driving at night both ways. I havn't tested what I will be getting around town but I would average 18.04mpg before I changed my sensor. I would average about 20.5mpg on hwy before I changed it.