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Fuel mileage for a lifted WD21 with M/Ts


JamesRich
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Just a quick Blurp about the O2 sensor. I know you said its a direct replacement from Autozone, but is it the actual Nissan O2 sensor. I remember people mentioning that the many aftermarket options for O2 sensors sometimes don't work the way they are supposed too. I think I recall Alkorahil mentioning the same thing and if I recall correctly then it might warrant more investigation before spending more cash elsewhere.

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My truck has a 5 speed trans. The O2 I got from Rock auto. I replaced it just because it was old, part of the tuneup. The original was still working correctly. I checked it with my old Snapon scanner. It gives me live reading on the O2 sensor and a few other sensors but nothing like an OBD2 system. I can watch the O2 switch from lean to rich and compare it to the mixture compensation. Mine are both switching at the same time which means its working correctly. When I unplugged the coolant sensor it stayed lean and would not switch back and forth. So you guys that were burning a lot of fuel with a bad coolant temp switch must have had a shorted switch to make it stay rich. My sensor is changing as the temp comes up but the impedance is to low. I verified the temp with a inferred thermometer.

Once I get to change it, probably Thursday, I will let y'all know how it does. I will probably compare the impedance readings with them side by side before installing the new one.

James

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I got the sensor changed out. This is definitely one of those things you should change when changing the timing belt! I ohmed the two sensors on a bench in my shed and there is a 200 ohm difference between the old and new one. These things are extremely sensitive, if I held it in my hand I could see the impedance change. My old sensor seems to sweep correctly even though the resistance is off but it might open or short when it gets too hot. When I pulled my 20 foot trailer the temp got up a little more than it usually runs and the truck started running like crap, it had a major hesitation. Now it seems to be running even better than it did before and no codes after the test drive, and I ran the hell out of it. Now I will fill the tank and see if it made a difference with my mileage.

If anyone else is interested I have an excel spreadsheet that keeps track of your mileage. You must enter your mileage and gallons used at every fillup though

James

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....

This truck could seriously use some ground cables. ...

 

 

I recently ran 4ga. grounds from the batter to the frame and the body.

It helped a lot with alternator whine in the stereo, fuel gauge reading correctly and many other little things.

I strongly recommend it.

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This sensor makes a big difference The truck runs much better. It has better throttle response, seems to have a little more acceleration, and doesn't sound like its straining just to keep highway speed anymore. Hopefully the fuel mileage come up too.

 

I put a grounding kit on my Titan now I see this one can use one too. If anywhere that is supposed to be a ground shows resistance to the negative post on the battery it needs a better ground wire. Just don't get carried away with enough cables to hold the motor up without the motor mounts!

James

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This sensor makes a big difference The truck runs much better. It has better throttle response, seems to have a little more acceleration, and doesn't sound like its straining just to keep highway speed anymore. Hopefully the fuel mileage come up too.

 

I put a grounding kit on my Titan now I see this one can use one too. If anywhere that is supposed to be a ground shows resistance to the negative post on the battery it needs a better ground wire. Just don't get carried away with enough cables to hold the motor up without the motor mounts!

James

 

Yeah, the sensors can cause some serious trouble, especially on 300ZXs (known as the Cylinder Head Temperature Sensor by the Z crowd) and MPFI Pathfinders. They seem to be a bit more reactive to the failing sensors than our (oops, your) TBI is. Glad to hear it's running better. :beer:

 

I keep forgetting to make some serious ground cables for mine, I've got way too much wiring laying around. Also, sometimes a significantly better ground with advance your timing a little so it might be worth it to double check that once you do it. :aok:

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Dang, there is a lot of variation as far as mileage goes.

 

I'm runnin 33's with an ARB and Steel rear bumper, and i'm getting around 16-17 all city driving, and when im strictly highway 19-22. Im finishing my tune up now because of my rough idle, so hopefully i'll see an even greater increase once i'm finished!

 

-Zepp

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IMHO Replacing the Engine Temp Sensor is something everyone should do on a WD21 if it has not been done before. The ECU get a lot of information from that sensor. There are probably a lot of people out there driving around with a bad one/not functioning properly and dont know it.

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Woohoo first tank with the new sensor is almost 17mpg in town. That way up from the 14mpg I was getting before. Hopefully the highway is better too.

James

 

Is that the same as the Coolant temp sensor?

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And it's a bitch to replace, that's for sure! I replaced mine when I put the new motor in and had the entire top end taken apart. Cheap insurance, even if the sensor only had 102,000 miles on it. 17 is definitely better than 14!

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And it's a bitch to replace, that's for sure! I replaced mine when I put the new motor in and had the entire top end taken apart. Cheap insurance, even if the sensor only had 102,000 miles on it. 17 is definitely better than 14!

That's an understatement! It's worse than replacing the timing belt because you have to dig deeper. I'm looking for round tooth sprockets for mine for when I change the timing belt. When I do I'm replacing this sensor again. For $19 bucks you can't beat the insurance. My truck only has 108k on the whole thing and the sensor has been crapping out since before I bought it. It wasn't out completely just reading around 300 ohms off. I guess telling the computer it was colder than it was. So even if its running fine change the sensor when you change the timing belt.

James

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Yeah it is really hard on the older ones. On the mpfi pathys is right in front of you and takes 5 min to change. I have 200k miles and mine is original. Maybe I should change it.

My wife drives an 01 Quest with around 130k. We bought it new so I know the temp sensors never been changed. If its that easy to change on the quest I will swap it just because.

James

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Yeah it is really hard on the older ones. On the mpfi pathys is right in front of you and takes 5 min to change. I have 200k miles and mine is original. Maybe I should change it.

Yep, exactly. Yet another superior feature on the 4 door... :tongue:

 

B

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Yeah it is really hard on the older ones. On the mpfi pathys is right in front of you and takes 5 min to change. I have 200k miles and mine is original. Maybe I should change it.

 

Mind posting a pic of where it's at?

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Yep, exactly. Yet another superior feature on the 4 door... :tongue:

 

B

Mind posting a pic of where it's at?

 

See what you got yourself into Mr "superior feature" Now go get your camera! :tongue:

James

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Mind posting a pic of where it's at?

Sure. It one of the two sensors in the housing after the upper radiator hose. I believe it is the yellow, rear most one...

DSC_0580-Copy.jpg

 

See what you got yourself into Mr "superior feature" Now go get your camera! :tongue:

James

I did, it just took a while because my mom stopped by and I Rainex'd her windshield and replaced her wiper blades.

Have you found your superior feature round tooth sprockets yet?? I believe those come off of 4 doors also... :whistle:

 

:lol:

 

:itsallgood:

 

B

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Interesting to see the sensor on the later MPFI WD21s actually being true to the name of "coolant temperature sensor" as it actually measures the temperature of the coolant. The earlier TBI Pathfinder sensors have nothing to do with coolant because it measures the temperature of the cylinder head, and it's proper name is the Cylinder Head Temperature Sensor or CHTS. They all basically mean the same thing, just loose terminology gets thrown around.

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I did, it just took a while because my mom stopped by and I Rainex'd her windshield and replaced her wiper blades.

Have you found your superior feature round tooth sprockets yet?? I believe those come off of 4 doors also... :whistle:

 

:lol:

 

:itsallgood:

 

B

Ok you got me there! I'll shut up now. :hide:

James

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