# '89 Sentra B12 has me baffled!!



## pedroelmalo (Jul 3, 2012)

Hello, I'm a first time poster, but I have been lurking for a while. Well, the issue I have is as follows; a couple of months back I bought a '89 Sentra 4 speed, the clutch needed to be replaced and since I had already done one in a '93 model I knew I could tackle that. I drove the car about 15 miles with the old clutch slipping, but I had no other way to get it home. Anyway, the clutch was replaced with a Luk unit, after the cable got adjusted and all it ran fine. The issue I have now, is that I have no gas going into the Throttle Body, if I pour gas down it, like a carb, it will run for a second or two. 

It happened all of a sudden though. I test drove the car after clutch was replaced. The sentra would start fine, then the second day it started and it would buck while i was driving if I held in gear too long, like if I went over 20 on second gear for example. I had trouble like that before in a friend's car and it was a sensor that had dirty connectors, so I went and cleaned the MAF connector and the bucking stopped. Along with the power loss. 

The next day I started the car up again, and while idling in my driveway it just up and died. And I cannot get it going. Is really frustrating, I mean, I'm not a certified mechanic, but I have a pretty good idea of what I'm doing,(or thought I did). It has been 3 days since this happened, I have tested the fuel pump, a friend has a gauge, it read 36, distribuitor cap along with plugs and wires and rotor was replaced at the time the clutch was replaced, as it was the oil filter and oil. 

I apologize if this has been asked before, but I need help!!! Has anybody ran into this problem before? When I bought the car it had been sitting like 8 months and I went ahead and replaced the old gas with new gas in the tank, as well as the gas filter. If I run a ground to the injector it works, I guess is just not getting current while it needs it? Please help!!!


thanks, I will keep you updated and will follow the advice provided....

:newbie:


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## rogoman (Dec 16, 2004)

When you replaced the clutch, in the precess, you may have disconnected one or more engine electrical grounds and failed to tighten them afterwards.


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## pedroelmalo (Jul 3, 2012)

will check all my grounds this afternoon after the sun lets up a bit is 103 in the shade today


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## pedroelmalo (Jul 3, 2012)

Well, I checked and cleaned and retightened all the grounds that I could find and even added one just to be on the safe side,(I went to the junkyard this morning and found a sentra like mine, and at some point my original ground cable was cut and a new terminal put on, so it was missing the part that connects to the fender.) 

Anyway, I tested the pulse to the injector with a test light (hope I did it right) went to a power and tested on the motor for ground and worked, and then, took the little cover for the injector and went to the negative side with the light, and had my daughter crank the car. The light barely lit up. Also I noticed that my temperature gauge moves all the way to the top, like the car was overheated... could that be the problem? :? I know for a fact that some cars wont start while overheated, only that my car has not run for like 4 days now... So now what?

And, where is the temperature sensor located? if indeed that is the problem? thanks again for the help

:newbie: :loser:


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## dreamteam (Jul 29, 2005)

Well, Pedro, I think you might have pinched the wire running to the temp sensor.
The sensor works as follows: high resistance when cold, low resistance when hot.
IN other words, the hotter it gets, the more it grounds out. The ground provides the path to lift the needle on your temp guage.
Therefore if the wire to the guage is making contact with metal the guage will rise.
So, it is possible that you pinched the wire when you replaced the clutch.
Look down below your throttle body for loose or pinched wires.

Two other things to check.
Make sure all the wires that ran directly to the positive and negative cables on the battery are connected.
Check the connection and the ground to the ECU.


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## pedroelmalo (Jul 3, 2012)

thanks, will do


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## pedroelmalo (Jul 3, 2012)

[/IMG]

Are these the ECU grounds?


and what are these connectors to?








[/IMG]

I ask this because the top connector was chopped from some other car I thinks, and two wires I know connect to something, one to the oil sensor, the other one I have no idea to what, but is hooked up. Three wires were cut and are not hooked up to anything. I have no idea what that connector does, in the picture is the one with the spliced wires.








[/IMG]

THis is the engine temperature sensor right?

I checked the connections and they look good, still I unplugged it and temp gauge still jumped all the way to the top and car still will not start  What else can I do now? Ignition Module Control? I swapped the relays by the firewall and the one by the battery, two blues and a brown, I don't know if that is going to fix anything, is just that on my way from the junkyard they came home with me, they figured I was lonely 



a couple of more pics of the offending Sentra...








[/IMG]








[/IMG]

:newbie:


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## dreamteam (Jul 29, 2005)

OK, those are grounds, and they look good.
Not what i was referring to though.
The ECU is located under the passenger seat.
Check to see that it is plugged in and making good contact.
Second picture......oh,oh.
Pink ladies, those nasty little wire connectors.
Don't trust them,cut and splice those wires back together.
Third pic, No.....that's not the temp sender. It is the thermoswitch
that turns on your radiator fan.
The engine temp sensor is located below the throttle body( in a really shitty place)
in a coolant passage in the head.
Now, I am going to walk out to my shop at two in the morning to look at those connectors.(yawn) Well, that was interesting. Those relays are supposed to have a cover over them that lists what the relay is for. The one by the strut is for horn, middle one is lamp check and auto choke, next one is rad fan

Synopsis.......I still think this is a wiring problem. Cut out those pink ladies and match the wires color to color.

BTW nice to see a rust free B-12.


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## pedroelmalo (Jul 3, 2012)

thanks, I'll be going under the sentra this afternoon to find the engine temp sensor...


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## dreamteam (Jul 29, 2005)

*Wire it first*

The sensor may not be the problem.
Here is a picture and definition of the factory wiring.



























picture two:
Front of connector that faces back of headlight,
fender side/top to bottom.
Pin 1 yellow/green stripe
Pin 2 green/black stripe
Pin 3 red/black stripe
Engine side/top to bottom.
Pin 1 black
Pin 2 brown
Pin 3 red/blue stripe

picture three:
Back of connector that faces firewall.
Fender side, top to bottom.
Pin 1 yellow/green stripe
Pin 2 green/black stripe
Pin 3 red/black
Engine side/top to bottom
Pin 1 no wire
Pin 2 brown
Pin 3 red/blue stripe.

OK, so much for the details.
You can see by the description that the wires 
need to match each other.

I would do this before changing anything else.
I am pretty sure once the wires are matched up,
the other problems will be solved.

Heck, you could even just cut the connector out
and match the wires up directly to each other.


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## pedroelmalo (Jul 3, 2012)

Thanks, I re-spliced the wires, but like I said 3 don't hook up to anything, they are cut at the end. One goes to the Oil Sensor, the other one goes to something else that I can't see, I will go under the sentra one more time this afternoon, when I get home, and see if I can figure out where that goes, or maybe I can figure it out looking at the manual, the electrical wiring diagram or something.


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## pedroelmalo (Jul 3, 2012)

With the wires re-spliced I have a true reading of the temp gauge now, I figured out the other wire was running to the sensor under the intake... but not running still...I noticed that when turning the key I get just a click, not a crank of the starter, just a click, like when there is no power left in the battery. sometimes though, sometimes I do get a good crank. Can it be the ignition switch??? still dead in the driveway!!


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## dreamteam (Jul 29, 2005)

OK, check the color code of the wires that are not hooked up.
let's see if we can figure out where they go.
Next, yeah ignition switches can fail,I suspect something else is also
going on here.


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## pedroelmalo (Jul 3, 2012)

Ok, the wires that are cut are as follow, Red/blk, red/blue and brown. But like I said before, the car ran, it was just while sitting in my driveway idling that it died. This is so frustrating for me and my wife nagging me about the car that I'm thinking of putting it up for sale if I can't figure out what is wrong, could it be a timing issue? I mean would the distribuitor have something to do with the injector pulse? If i need a new distribuitor I can go and source one at the junkyard before I buy a new one... 


and thanks for all of your help


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## dreamteam (Jul 29, 2005)

Yeah, if I was there, I'd probably buy it!
But then my wifes not too happy about the dozen or so
cars I already have.
Back to the problem: look at post #10.
The wires you describe are on both sides of the connector.
Peel the tape back on the other connector and you will
see what I'm talking about. Match these wires up and splice them together.
Also, show me a close-up shot of your battery and cables.


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## pedroelmalo (Jul 3, 2012)

I will cut and splice, but on the back (pic 2) is where they are cut and dont go to anything, I will also take some pics of the battery and the wires and post it later on, and yeah Im hoping I can get it running soon or Im gonna be sleeping in the garage


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## pedroelmalo (Jul 3, 2012)

sorry, I meant pic 3


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## pedroelmalo (Jul 3, 2012)

The update!!!!! Finally!!! this morning I made a trip to the local pic a part, and after much hunting I found a 4 spd Sentra, I decided to swap out my computer and my distribuitor since I thought those were the only two things I had left to change, so I picked up both, for 27.50 a piece (plus a core charge on the computer would you believe? junkyards charging for cores... oh well...) 


Anyway, I got home and it was hot as hell, so I waited til about 6 this afternoon and decided to tackle the Sentra one more time, or I would have had to sell it not running... I had the battery charging with a slow charger that I had picked up for 2 bucks at a local second hand store, (always great tools there). I went for the computer first, it was faster and I had no battery on the car anyway, I hooked the battery back up, and damn if it didn't start at the third crank!!!! I'm so stoked!!!!


The idle is a bit faster than I like but everything is working as far as the engine. I guess the speedo cable got loose or something because now I don't have a speedo reading, but I figured I can drive with no speedo back and forth to work, and get me a sweet 35 mpg at least.

Thanks to everyone who pitched in, and one last thing. Does anybody know how to lower the idle? Is not like a carburator is it?

:givebeer: :newbie:


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## uudfourty (Jul 11, 2012)

Did you get your idle figured out?


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## pedroelmalo (Jul 3, 2012)

no, not yet, also it takes a bit to start in the mornings, when its been sitting overnite, does it have a choke? like a manual choke?


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