8 Mpg In My 93

[killerFatty]

Lately I have been doing more consistant driving and have found that I have been getting aroun 8 or 9 mpg even though i rarly go past 2800 rpm. Most all of my driving is city, but still I would like to think that I could get at least 12 or 14. My LS is in good mechanical condition. It had a major tune up at the dealer about a year ago, air filter is still good. The coolent temp. sensor was replaced about 6 months ago. The only thing I can think of is the PS pump leaking a tiny, tiny bit into the block. I check the ps fluid every month and have never had to add any so I dont think its major at all. My rotors are a little warped, but I dont feel any break drag or pull when I drive. BTW I tried searching the forum, but I couldn't find anything else. The search function needs some help. Any input would be great. Thanks guys.

[curiousB]

Lately I have been doing more consistant driving and have found that I have been getting aroun 8 or 9 mpg even though i rarly go past 2800 rpm. Most all of my driving is city, but still I would like to think that I could get at least 12 or 14. My LS is in good mechanical condition. It had a major tune up at the dealer about a year ago, air filter is still good. The coolent temp. sensor was replaced about 6 months ago. The only thing I can think of is the PS pump leaking a tiny, tiny bit into the block. I check the ps fluid every month and have never had to add any so I dont think its major at all. My rotors are a little warped, but I dont feel any break drag or pull when I drive. BTW I tried searching the forum, but I couldn't find anything else. The search function needs some help. Any input would be great. Thanks guys.

Well the way to test if your brakes are dragging is to go for a ride where you won't need to use them and then glide to a stop and then go feel wheel to see if they are hot. If brakes are dragging they'll be plenty of heat.

Other than that maybe Fuel Injection problem where engine is running open loop which is wasteful of fuel.

Also how did you compute your mileage? Did you start with a full tank, go for drive that used at least 1/2 tank then divide distance travels by gallons needed to refill tank.

[killerFatty]

Thanks. I'll try your break test tomorrow. What exactly happens when the engine is in open loop mode. It sounds familiar, but I'm not sure what it is. The better question is how do I fix it? Thanks.

[curiousB]

Thanks. I'll try your break test tomorrow. What exactly happens when the engine is in open loop mode. It sounds familiar, but I'm not sure what it is. The better question is how do I fix it? Thanks.

Open loop mode is when the ECU isn't controlling fuel mix based on the O2 sensors on the exhaust. It happens intentionally when you first start your car as the O2 sensors need to warm up before they have accurate signals. If there is a problem in the O2 sensors or some other type of Fuel injection problem the system reverts to open loop mode so the car will be functional. It won't pass an emissions test and mileage will be poor because to be safe it intentionally runs engine on the rich side. The way to check is to attach OBD2 reader and see if the car is stuck in open loop mode. Usual cause is the O2 sensor but it can other things like too high fuel pressure (fuel regulator not working right), engine temp sensor faulty, and so on. Most failures will log an error code and light up the check engine light.

[killerFatty]

Can I attach a obd II to a 93? I thought my car was OBD I only. I dont have a cel. My trac light has been on since i got the car. I think it has to do with the TPS. Would that cause open loop mode? I checked my brakes like you said, and they were fine. Is there a way to test O2 sensors even if they are not throwing codes?

[Jeffstpetebeach]

If you have an ohnmeter you can test them. here is a file to shoow you how. good luck hope this helps your searcho2sensor_check.pdf