Nissan Forum banner

1 - 20 of 33 Posts

·
Registered
Joined
·
61 Posts
Discussion Starter #1
Can someone direct me to a site that shows you the location of the following sensors:
1) O2 sensor
2) Engine temp sensor (cylinder sensor) not the watercoolant sensor


it would help if there were pictures of it too.

Trying to DIY some replacement.

Also my car has a hard start problem and after reading 'extensively', my guess to the problem is the above 2 components.

Any expert advise is much appreciated.
 

·
Registered
Joined
·
79 Posts
If the O2 sensor is going, it shouldn't have any problems starting, but you're fuel milage will drop. Its located on the exhaust header, you should see it on the front of the engine sticking out of the metal heat shield with three wires.

Not sure about the engine temp sensor.

Aaron
 

·
Your electrical friend
Joined
·
2,177 Posts
I'll take a look in my FSM when I get home and let you know what I find. If you can't find your 02 sensor I'll take a pic of the one in my XE and post it for you. You'll need to borrow/purchase a special socket to remove the sensor. You might be able to get by without it if you remove the exhaust header heat shield and use a wrench but it's not easy to do it that way. I took one out of a '91 Tempo my wife had, that way. It was not easy.
 

·
Your electrical friend
Joined
·
2,177 Posts
Well from what I can find in the FSM the Thermal Transmittor, which appears to be what you're asking about, appears to be a single wire connector underneath the throttle body.

EDIT: Okay, well I went out and looked at my car, and there is a single wire connector that hooks up to a sensor that is just underneath the coil and this sensor is in the lower portion of the head, so it's right above the block. This would make sense then, that it would be the cylinder temp sensor you're looking for. I'd take a picture but: 1) I don't have a digital camera at the moment 2) I don't think I could get a good picture of it in the first place. It's right under the coil, you can't miss it, it's the only thing there.
 

·
Registered
Joined
·
61 Posts
Discussion Starter #6
hi,

to toolapcfan: thanx. I looked and I found one connector with 2 wires under the coil. You can see it thru the distributor. It appears to be installed into the engine block. Is this the one ?Now that seems odd as you mentioned that there is only 1 wire. How is it that mine has 2 ?

to luminus:I tried to find the O2 sensor, but didn't see any component or wires sticking out from the exhaust header. Would I be able to see it under the front middle of the car? Near thr grille

This hard start problem really has puzzled many a mechanic. Replaced the AAC valve, distributor, battery and starter motor. Had installed new fuel pumps and filter too. Including new plugs, cable and air filter. What else other than coil, power transistor, temp sensor and O2.

My mileage also seems to vary between 8km/litre to 10km/litre (sorry I dun use mpg calculation). With all other driving and road conditions being equal.

Is this a challenge to the experts or what ?
The local dealer will charge me an arm and leg for the repairs.
So better to DIY.
 

·
Your electrical friend
Joined
·
2,177 Posts
I suppose it could have been two wires, but it's a single terminal connector that connects to a single spade terminal sticking out of the head. It's clearly a sensor and not a ground clip. If the O2 sensor were a snake you'd be dead, I'll guarantee it. ;) Open your hood and look at your exhaust header, there is a thing right in the middle of it, it has a black wire that runs to a little red cone shaped plastic connector that hooks up to a thick black cable. This thing sticking out of your header is the 02 sensor. It's right on the top of the header, near where it connects to the head.
 

·
Ive got a pickle 4 an arm
Joined
·
340 Posts
i just replaced my O2 sensor. i believe that GA's only have one wire running from them. i replaced it with a bosch one. the wire was longer, wich isn't nessarily a bad thing. the holder on my heat shield rusted off so now i just tied it somewhere else.

But, i had replaced it to solve my LOW FUEL MILEAGE problem. i've been getting around 26-31mpg. really really low for a car rated at 38!!!. so far i've only put in one tank and my mileage looks to end up at 27-28. not any better at all. i wonder if my Advanced timing and 93 octane has anything to do with the mileage problem. i advanced and upgraded the fuel about a week or so b4 putting in the sensor. i still would think i'd gain at least 2mpg, but so far, didly squat! the car feels tourqier, but i credit that to the timming.

as a hint to change the o2: my uncle had to modify an old wrench to fit into the gap in the header, shaving the outside of the wrench, and cutting the handle in half. the size for the GA is 22mm. and it helps to try to REMOVE WHEN THE ENGINE IS WARM. just grab an old pot holder, your wrench, a small hammer, and a screwdriver. put the wrench in place, use the screwdriver to hold it in place, so you don't have to touch it, it will get hot very fast. then hit the wrench with the hammer. after a few taps the sensor should come out with no problems.!!! after a few taps you can take the pot holder and just unscrew the sensor the rest of the way. oh yea be sure to unplug the wire first, jsut move the boot out of the way and wiggle the wire away, don't worry about breaking the boot, the new sensor has one with it. PLUS it include some anti seize on the threads, DO NO REMOVE, or else you will have an even harder time to remove next time, like if your buying a header or whatever.

remember HEAT HELPS!!!

i'd post a pic but the rules say that i can't post attachments, and i have no idea how to do it any other way i could AIM it to ya, but we'd have to be connected
 

·
ex-Super *********
Joined
·
1,410 Posts
Ill try to help here.
On my B14 with a GA, which is probly the same as your car. There are 2 temp sensors. One is for the gauge and it is a one-wire sensor. The other is for the ECU, this is the one I assume you need to locate. On My GA the one under the distributer is a one-wire, thats the one that runs the gauge(I have confirmed this). the 2 wire one is on the intake manifold side(rear) of the engine. If you look behind the oil fill cap down twords the intake manifold thats where it is, dont quote my on this, but i belive the wire colors are brown/yellow and black(this is on a B14 yours may be different.) A B13 MPFI GA should be set up the same as a B14 MPFI GA. Ill take a look around my car tommorow(pics too)

BTW they are both water temp sensors

The O2 sensor(s) will be the only thing screwed into your exhaust with wires coming out of it. If you need help with testing these thing give me a holla. One more thing.. If you are having trouble with your car starting its probly not the O2 sensor. The ECU doesnt give a $hit what the O2 sensor says at start-up.
As for the temp sensor causing it.. again probly not, but it would make your ecu either dump too much or too little fuel at start-up.
If you are still suspecting these though, like I said give me a holla and I will help you with how to test them.
Why excatly is your car a hard start.. does it crank but not start of does it not crank at all some times?
 

·
Ive got a pickle 4 an arm
Joined
·
340 Posts
PatScottAKA99XE said:
Ill try to help here.
On my B14 with a GA, which is probly the same as your car.
his profile says its a B13. i know my B13 has only one o2 sensor, in the header. i even got the Haynes manual to back me up on that one, it mentions only one sensor in the header. i hear others speak of two in B14s

sorry i read your post two fast, i've edited it like 4 times already
 

·
Registered
Joined
·
61 Posts
Discussion Starter #12
Hi guys

third time I'm posting .. some problems with the BB that keeps saying I'm an unregistered guest even after logging on.

Thanx to all for the valuable advice.

I found the temp sensor that I think goes to the gauge. It's a single wire. I cleaned the contacts but my problem still persisted.

Will look next for the other engine temp sensor.

Still have yet to find the O2 sensor. Do I have to remove the engine guard (plastic cover) under the front to see the O2 ?

My hard start problem begins like this:
In the morning, it takes about 3-4 cranks to get the engine to run.
Or I could crank at one go for ~5secs to get the engine to run.

Once it runs, no peoblem.
When I stop the engine and crank it within 10 mins, it'll be normal and ok.
Have to leave the engine to cool down totally in order to replicate the problem. SOmetimes 30 mins, sometime 6 hrs.

It doesn't help that I dun have a diagnostic computer nor the technica l manual. And mechanic costs here are really expensive.

I've actually narrowed down the problem to a few components:
coil, power transistor and engine temp sensor.

Does anyone know the part number or OEM parts that can be used?

Hope I can solve it soon.
 

·
Ive got a pickle 4 an arm
Joined
·
340 Posts
i was getting the same problems loggin in. in fact still have trouble with it from time to time. at one point it got so bad that i couldn't go anywhere at all. i hit any link after logging in, and i'm suddenly logged out. even trying to get to my user profile would log me out again! i had to turn off the use of cookies and now i need to log in everytime i visit the site.

i'm still puzzeled that you can't find the o2 sensor. pop up your hood, then look down at the engine. on the front of the engine, which should be in plan sight, is the header. unless you had someone install a new aftermarket header, there should be sticking up, a goldish colored thingy plugged into the header. with a single wire leading out the top of it. see if you can find it in this pic:


if your engine doesn't look anything like that, well i'm stumped. this image is out of an NX from the first NPM issue, but the engine is the same.
 

·
ex-Super *********
Joined
·
1,410 Posts
ace,
Here is a pic of the ECU's water temp sensor on a GA:



For reference, you can see just a bit of the oil cap in the lower right hand portion of the pic.
 

·
Registered
Joined
·
61 Posts
Discussion Starter #15
Hi, thanx guys for the pix.

that really helped alot. Now I know why I couldn't find the O2 sensor, coz there's this metal plate (shield or guard) that covers that portion. In addition I've been trying to look at the sensor from under the car.. from my experience with continental cars.

As for the engine temp sensor, I did a quick check and found it too. Lot's of grime and soot. And the connector's a little bit broken. Guess the heat in the engine compartment may have caused the plastic to breakdown.

Can anyone tell me the part number of the items so that I can get it at the local auto shop ? Can any O2 sensor or temp sensor do ?

I've decided to get an after market coil. May have to do some modification to the wiring and connector.
I've replaced the plug cable from coil to distributor, but still the problem persists.

Got to remove the engine cover and sheesh.. looks like the engines got lung cancer or something...all the gunk and thick goo. Can this result in hard starts ? Any meands to flush all of that gunk out without having to put new engine seals or grind the cylinder heads ?
My local mechanic advises against pouring additives or flushing the engine. An 11 yr old car might give off white smoke after that. According to him.
 

·
Your electrical friend
Joined
·
2,177 Posts
Ace, I thought you wanted the cylinder temp sensor? That's the one under your coil. The one Pat took a picture of is the water temp sensor.

Originally posted by ScarCrow:
"...see if you can find it in this pic:"


I found it! What did I win? :)
 

·
ex-Super *********
Joined
·
1,410 Posts
toolapcfan said:
Ace, I thought you wanted the cylinder temp sensor? That's the one under your coil. The one Pat took a picture of is the water temp sensor.

For clearification:
They are both water temp sensors.

The one under the dist. is only for the dash temp qauge.

The one in my pic is where the ECU gets its temp readings from.

The one under the dist. has absolutley no affect on how the engine runs.

The one in my pic has an affect on how the engine runs.
 

·
Registered
Joined
·
61 Posts
Discussion Starter #18
Hi,

yep. I need to know the sensor where the ECU will take readings from.

My hard start problem seems to be getting worse.

Takes more cranks and a longer time to get the engine running.

Do any of you guys think that by resetting the ECU will help ? Or does the ECU actually reset each time you crank the car.

I've read somewhere that the ECU updates the last 50 cranks for diagnostics. Not sure if the ECU gets 'affected' by the history of problems.
 

·
ex-Super *********
Joined
·
1,410 Posts
Then you need the one in my pic.
History problems will not affect the running of your engine. It stores them for guys like me(technicians), so that we can see if it has been a recurring problem. Resetting probably wont work.
I know GM's reset(clear history problems) after about 40 key cycles. If and only if the problem doesnt happen again during that 40. I dont know what Nissan cycle number is.

I cant do metric conversion either, but is your gas mileage(Km'ige?) worse than normal?
Have you noticed any other drivability problems? Even little things
Does this hard start happen all of the time?
just trying to get some info.
 

·
Registered
Joined
·
61 Posts
Discussion Starter #20
Had the chance to look into the bonnet yesterday and guess what I found ? Nothing.... the O2 sensor wasn't even close to where the picture was. None on the header, none under the header.. very puzzling !! No wires were seen coming out from anywhere near or in the exhaust header. Did I miss something?
I didn't see any longish sensor that we recognise as an O2 sensor.
Is the sensor only used in manual cars ? Mine's automatic.
A challenge to you experts out there ?

Yes the hard start happens all the time. Previously I could start the engine without problems within an hour after shutting the engine. But it seems like even 30mins after shutting down, I need at least 3-4 cranks to get the engine to kick in.

I sprayed the contacts of the power transistor and coil with contact cleaner and that seemed to work. But only briefly. What I can describe is that there is a difference in the cranking sound produced for a hard start versus a good one time start. A good crank produces a low frequency crank and vroom sound. Whereas a hard start produces a weaker cranking sound as if the battery had no juice.

Also, is there a fuel pressure regulator / valve or sensor that determines the fuel pressure around the fuel lines ? I thought the fuel line only consists of the fuel pump and filter. Any components around here ?

My gas mileage goes between 8-10 km per litre. Same conditions in driving.
 
1 - 20 of 33 Posts
Top