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1996 LS400 MPG issue?

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Old 02-07-17, 08:09 PM
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winter4w
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Default 1996 LS400 MPG issue?

So I went to see how good of MPG I get and I guessed around 13 MPG. I need to refill my tank up after I hit 275-300 miles. The reason I know this is because evert time I fill up gas I reset the Trip A. Is this normal or is there something wrong. Google says I should be getting 19 city / 26 highway.
Old 02-07-17, 09:37 PM
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Banshee365
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Any codes? Does your exhaust smell like rotten eggs?

A few things that can cause mpg loss are stuck thermostat, bad coolant temp sensor, dragging brakes/parking brake malfunction, etc...
Old 02-07-17, 10:05 PM
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RA40
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Vacuum leaks too.

Just did a San Diego run and with 90% highway ours did 23.8 MPG.
Old 02-07-17, 11:45 PM
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winter4w
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Originally Posted by Banshee365
Any codes? Does your exhaust smell like rotten eggs?

A few things that can cause mpg loss are stuck thermostat, bad coolant temp sensor, dragging brakes/parking brake malfunction, etc...
No lights are on. I dont have a code reader (any recommendations off amazon I'll buy ). How will I be able to check the temp sensors or thermostat? And no brake dragging. the car moves on idle in drive.


Originally Posted by RA40
Vacuum leaks too.

Just did a San Diego run and with 90% highway ours did 23.8 MPG.
Yea something might be wrong with mine if I am getting 13 MPG. So far unaware of any vacuum leaks.
Old 02-08-17, 03:50 AM
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Losiracer2
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I get about 20.5mpg on my 97', about 400 to a tank when the light comes on. So 13 is pretty miserable.

Change the coolant temp sensor. You can get a replacement one at O'Reilly Auto for a decent price. 17-1408 is the Part Number. I paid about 17 bucks for mine I believe. It was literally the first maintenance item I replaced aside from light bulbs, air filter and an oil change on my car when I purchased it since I knew mine hadn't been touched.
Old 02-08-17, 08:59 AM
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winter4w
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Originally Posted by Losiracer2
I get about 20.5mpg on my 97', about 400 to a tank when the light comes on. So 13 is pretty miserable.

Change the coolant temp sensor. You can get a replacement one at O'Reilly Auto for a decent price. 17-1408 is the Part Number. I paid about 17 bucks for mine I believe. It was literally the first maintenance item I replaced aside from light bulbs, air filter and an oil change on my car when I purchased it since I knew mine hadn't been touched.

Yea last night I was reading some post on here and a lot of people with MPG issues said to replace it. I'm probably going to go with a OEM one since I like OEM parts more and will likely not have a issue with them OEM Part number: 89422-20010. The post I found that info on was here ()

Just to confirm the is the sensor near the front passenger side under that plastic casing that holds those cables?
Old 02-08-17, 11:07 AM
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Originally Posted by winter4w
Yea last night I was reading some post on here and a lot of people with MPG issues said to replace it. I'm probably going to go with a OEM one since I like OEM parts more and will likely not have a issue with them OEM Part number: 89422-20010. The post I found that info on was here ()

Just to confirm the is the sensor near the front passenger side under that plastic casing that holds those cables?
Good idea with the OEM part. And yes, that's it.
Old 02-08-17, 12:02 PM
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Originally Posted by Banshee365
Good idea with the OEM part. And yes, that's it.
Ok I am a bit lost on how I am supposed to remove that plastic piece that's in the way. Mine is broken in half so it looks like I only need to take that cover off the left side however I am unable to get a good grip of the bottom left bolt unless I take apart some other things.

I guess Ill just take it to my mechanic to get it replaced if it comes to that.
Old 02-08-17, 10:18 PM
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Losiracer2
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Originally Posted by winter4w
Ok I am a bit lost on how I am supposed to remove that plastic piece that's in the way. Mine is broken in half so it looks like I only need to take that cover off the left side however I am unable to get a good grip of the bottom left bolt unless I take apart some other things.

I guess Ill just take it to my mechanic to get it replaced if it comes to that.
You need to remove the passenger side plastic cover for the camshaft and then move the spark plug wires and plastic routing for the wires out of the way a bit to be able to see it. Once you do this, I think you'll need either a 19mm or 22mm deep socket to remove the sensor after unclipping it from the connector. Took me about 15 minutes to do on a brand new to me car at the time. Look for a green connector, that's the coolant temp sensor.

My Import Direct sensor was manufactured in Brazil and is working fine over a year and a half later. Improved my mpgs from 19 to 21 for the trips I was doing for work. If it breaks, it has a lifetime warranty and is readily available at any O'Reillys so I won't have to special order it at Lexus.

Last edited by Losiracer2; 02-08-17 at 10:21 PM.
Old 02-08-17, 10:59 PM
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Originally Posted by Losiracer2
You need to remove the passenger side plastic cover for the camshaft and then move the spark plug wires and plastic routing for the wires out of the way a bit to be able to see it. Once you do this, I think you'll need either a 19mm or 22mm deep socket to remove the sensor after unclipping it from the connector. Took me about 15 minutes to do on a brand new to me car at the time. Look for a green connector, that's the coolant temp sensor.

My Import Direct sensor was manufactured in Brazil and is working fine over a year and a half later. Improved my mpgs from 19 to 21 for the trips I was doing for work. If it breaks, it has a lifetime warranty and is readily available at any O'Reillys so I won't have to special order it at Lexus.
Yea I am having an issue trying to remove the cover off the passenger side. Are there only two bolts holding it on because I see one at the top and other at to bottom? However I don't have any tool to get the bolt at the bottom since the air intake pipe is in the way and I am too nervous to remove it lol.
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Old 02-08-17, 11:59 PM
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Originally Posted by winter4w
Yea I am having an issue trying to remove the cover off the passenger side. Are there only two bolts holding it on because I see one at the top and other at to bottom? However I don't have any tool to get the bolt at the bottom since the air intake pipe is in the way and I am too nervous to remove it lol.
you mean that big surfboard looking thing in the front? Haha, it's just held on with one 10mm bolt and slide it to the right about 3 inches and it'll come off.

Once you remove that it should give you more access to get the passenger side cam cover off
Old 02-09-17, 12:08 AM
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Originally Posted by Losiracer2
you mean that big surfboard looking thing in the front? Haha, it's just held on with one 10mm bolt and slide it to the right about 3 inches and it'll come off.

Once you remove that it should give you more access to get the passenger side cam cover off
No l was able to get that off, I am haveing trouble with the cam cover. I posted an image of the bolt I can't reach. What did you use to take it out?

Old 02-09-17, 06:36 AM
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Originally Posted by winter4w
No l was able to get that off, I am haveing trouble with the cam cover. I posted an image of the bolt I can't reach. What did you use to take it out?

oh, that bolt. Looks like you can use a 1/4" 10mm socket with an extension for that. I think ended up removing the inatje system all the way to the throttle body to give me more clearance as well. Only took another 5 min of undoing hose clamps
Old 02-09-17, 07:06 AM
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There are a total of 4 bolts with 10mm head heads holding on each top timing cover. Two across the plug wire area and two up front. The drivers side is easily removable in about 30 seconds. The pass side requires removal of the air intake connector to the throttle body to access the two bolts over the plug wires. The wire holder blocking the ECT sensor is also supposed to be held down by a studded bolt that fastens into the coil bracket.

Dont take all your car to a mechanic for this man, use this opportunity to learn something about your car. If you need to buy a couple of new tools, big deal. You'll always use them later. On the drivers side, with the air intake connector and such all of the bolts are easily accessible with a 1/4 drive 10mm socket and extension.
Old 02-09-17, 08:09 AM
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The air intake needs to be remove to get at that bolt


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