Gas mileage sucks in my 89 Exi automatic

[MoDawG]

I get 300 out the whole tank if im lucky..Do I need a tune up?

[carotman]

300 miles or 300 kms?

[MoDawG]

300 miles or 300 kms?

sorry km

[labeledsk8r]

300kms out of a full full tank? then yes i would say a tuneup would help, do you drive conservitive or flooring it all the time?

[MoDawG]

300kms out of a full full tank? then yes i would say a tuneup would help, do you drive conservitive or flooring it all the time?

I drive conservative, i floor it here and there

[MessyHonda]

yeah tune up and a oil change...when i changed my dirty 5k oil i got a 2-3 miles per gal bump.

[carotman]

I would suspect the Engine Coolant Temp sensor. 300km is really too low.

[MoDawG]

I would suspect the Engine Coolant Temp sensor. 300km is really too low.

How would that one affect fuel mileage? The fan does not turn on so I recently rigged up a switch to turn it on. The fan thermoswitch is fcuked

[Hauntd ca3]

if the coolant temp sensor is a bit funny
it'll tell the ecu the motor is cold and it will keep feeding it a rich mixture
dont know much bout the amount of sensors on the exi, but alot of modern cars have two temp sensors
one for the computer and one for the gauge

[MoDawG]

Hmm, I know my thermoswitch sensor is fucked, the car over heats now and then I rigged up a switch to turn it on manually when the temp is getting a lil high

if the coolant temp sensor is a bit funny
it'll tell the ecu the motor is cold and it will keep feeding it a rich mixture
dont know much bout the amount of sensors on the exi, but alot of modern cars have two temp sensors
one for the computer and one for the gauge

[mbc]

MoDawG,

I've been reading up alot recently on this subject. From what I gather, aside from a tune up, Check and adjust the ign timing. If you advance it, you'll see better fuel economy. Also, check to make sure that your distributor vacuum advance is working properly. Check that both vacuum hoses going to the diaphragm on the dist have suction when required.

Hondas were designed to run hot. This reduces emissions and helps improve fuel economy. Make sure that your thermostat is rated at the proper temp. I think that it's 195*F. The advice you have recieved is correct, if the coolant temp is too low, the A/F ratio will richen. One thing to consider is that cold temps and winter blend gasolines are arriving. Use 30W oil to reduce drag on the moving parts, check tire pressures, reduce vehicle weight, and use Honda ATF to optimize transmission function. I'm sure there are more things, but it's Friday and I started drinking.

[redaztec]

It also occurs to me to ask, are you driving it for longer or shorter trips? When I drive my 3G on a lot of short trips (which is how I usually drive it), it'll get very poor mileage like what you are describing. However it'll do 30+ mpg on the highway.

[MoDawG]

It also occurs to me to ask, are you driving it for longer or shorter trips? When I drive my 3G on a lot of short trips (which is how I usually drive it), it'll get very poor mileage like what you are describing. However it'll do 30+ mpg on the highway.

Yah it is mostly short trips actually

[carotman]

Actually, there are 3 thermo switch. One at the bottom of the radiator to control the fan, one for the gauge and one for the ECU.

The one for the ECU is located on the thermostat housing and has 2 wires going to it.

[Estimated Prophet]

The one for the ECU is located on the thermostat housing and has 2 wires going to it.

How do you verify their functionality? Especially curious about the ECU one on the thermo housing.

[2oodoor]

How do you verify their functionality? Especially curious about the ECU one on the thermo housing.

hey long time no see !
interface with scan tool is the only way I know of for certain, to check the actual temp.
Or do you mean how to tell which one is guage and which one is ECU?

The on on the thermo housing is for ECU most of the time.

[Estimated Prophet]

I was curious if it was something you could test the ohms on a multimeter.

[2oodoor]

yes you can test the sensor itself , disconnect the wire and measure resis. between the sensors terminal, should be between 200-400 ohms. .

[LXlimited]

my gas mileage sucks too. i have an 87 accord with carb that gets 20mpg mix driving. i did a full tune up(air filter, gas filters, oil change, spark plugs and wires, pcv and hose. my choke was also recently changed. i spray some carb cleaner in the carb but it did not help. i do have an oil leak in the rear main seal. could that cause the problem? what else could be wrong? thanks in advance!

[turabaka]

Actually, there are 3 thermo switch. One at the bottom of the radiator to control the fan, one for the gauge and one for the ECU.

The one for the ECU is located on the thermostat housing and has 2 wires going to it.

what color are the two wires?

[MoDawG]

I changed the plugs/wires., did an oil change and ran seafoam through my system.. The gas mileage got a little better I guess.