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Discussion Starter #1 (Edited)
hey i have a 91 sentra xe 1.6l 5spd
when i start the car it starts right up, then immediatly dies. if i start it and give it gas for a few seconds then let off it will idle, but barely (around 400 rpm)it will not die any time after this, only AT start up. a buddy told me it could be the idle air control valve. i just changed the spark plugs and fixed a hole in my exhaust. any ideas.
thx
OK i just went to my shop at work and took out the IACV and cleaned it out thoroughly, and still, start=die./start+gas= run?!?! any ideas?!
 

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Discussion Starter #3
well if ANYONE has ANY suggestions, please let me know. also, car has an aftermarket ractive tach installed from owner before me. the only problem with this is that it only works when you turn on the headlights.( hence he wired it to the dash lights or something,) anyway i dont care about the tach so much as it does not effect the performance of my car, i would however like it to start without assistance so PLEASE ANYBODY please help thank you
 

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A few possibilities I can think of would be O2 Sensor could be bad, Idle speed control unit... Have you checked around the engine to make sure there aren't any loose connectors or especially air hoses? Also you may want to change your fuel filter and take a look at the air filter, the air filter would have to be pretty clogged for that much trouble though... Has it been running poorly like this since you got it or did it just start happening. I'll look through the FSM and post again if I think of anything else. Let me know if any of the things I mentioned helps. Good luck
 

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I just had another thought, it's quite possible that the cold start valve isn't working properly also. I don't have the specs for it but if you have the manual and a meter you could test that. Aside from loose hoses or connectors or fuel filter, that's probably what I would check first.
 

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well i am bringing it in to the truck shop i work at tomorrow to change the oil. i know its not the air filter but will double check. the fuel filter looks like it was replaced,but whoever did it cut the hose or something because you can see this little plastic deal in between the now 2 sections of hose with a hose clamp that is way to big on either side...could be an issue of not enough fuel from there i guess, but why only affect at the start up of vehicle?
 

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I just had another thought, it's quite possible that the cold start valve isn't working properly also. I don't have the specs for it but if you have the manual and a meter you could test that. Aside from loose hoses or connectors or fuel filter, that's probably what I would check first.
Hi where is that cold start valve?

For mine the air filter is a K&N size for the factory box and it's clean. Fuel fliter is new .I'm about to change the sparks plugs. I'll Keep you update and thanks for the help.
 

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Not the easiest to get ot or the cheapest to replace but it's between the plenum and the intake manifold. It'll have an air hose, gas line and electrical connector going to it. But yea, it's pretty much in the middle of the intake, I don't know if you can get it off without pulling the plenum.
 

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Stop and Back up guys..... IAC=== Idle Air Controll ... 90% chance that if you clean it you'll fix the problem... A simple SEARCH should provide a how-to.. Or you could download the service manual that is in a Sticky (Do a search for "B13 service manual")
 

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Ok so you are talking about page 680 on Vol. 1 the IDLE AIR ADJUSTING UNIT right? also page 726 on Vol. 1 also talks about this problem

I'm in the process of taking off for cleaning. Dammit the gasket broke a little :mad:. any way a notice it pretty dirty but for all those years it could be worse.

Thanks for the heads up and i keep you posted and by the way new sparks already install
 

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The Next step I'd take would be to check the timing... If the timing is Low it could affect the idle like this... The other though is to check if the IAC is actually working, OR if its even getting the signal..

***This is all under the "ASSUMPTION" that youve got a clean air filter, Recent tune-up, And ALL vaccum hoses and Intake ducting are intact****

Which brings me to another point... It could be a Loose, Broken, cracked, clogged vaccum line...

Any recent work done Before this problem showed up???


***And just for SH!&S and Giggles.... I'D unhook the ALL the Tach wires until you remedy this... Electrical Gremlins are FINICKY creatures...***
 

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Discussion Starter #14
hey yeah, well i bought the car with this condition. so to answer your question no maintenence had been done prior to this happening. i have put new air filter spark plugs oil etc. (routine) since who knows when the previous owner has done these things. anyway, i will have to try unhooking tach wires due to potential gremlins haha. but how would you test if the IACV is working? oh all hoses seem to be going where they should and doing what they should.
thanks
 

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Well i finally found the problem. After cleaning the IDLE AIR ADJUSTING UNIT and no luck at firts try i keep searching the manual and working on the car i decide to check the engine temperature sensor and for my surprise :eek: it have water in it. I wash the motor a couple off days back :loser: clean that hole mess and now my long time working partner is starting like it use too.

Thanks againg for the help and good luck deboner whit your car
 

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a shorted temp sensor?
huh...no kiddin

before cleaning the IACV, i was gonna say tighten your throttle cable a touch...
it'd let more air in during idle *when you're not touching the pedal*

but see.. if a vacuum line is busted it just gets more air in when you're letting off the "air pedal"

vacuum lines only do certain things... cept one (on my car), the vacuum line that goes the the fuel pressure regulator. the other lines are for the egr and such.. not really needed. just lets air in. but if there's one hose that has a hole in it.. it will effect the whole vacuum system. giving it a lack of vacuum on the fuel pressure regulator.

but for it to work now, now that you dried the sensor off... wierd. though, an erroneous reading where it's shorting, giving the ecu too much voltage would tell the ecu that the engine is overheating when it's not.

like nasty nissan said.. just fix everything... tuning it all is fairly cheap. til you find a bad sensor, and that just requires a yard trip.
 

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but for it to work now, now that you dried the sensor off... wierd. though, an erroneous reading where it's shorting, giving the ecu too much voltage would tell the ecu that the engine is overheating when it's not.
Yeap ask a friend of mine that is a mechanic and told me the same thing.
 

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OHMS----Resistance is a weird thing... The water changed the resistance of the wire/sensor and the ECM went wacky....

Deboner..... You'll need a volt/ohm meter (Digital) and the Service manual. The manual should have testing procedures and specs for the voltages. You should probably check the temp sensor as that could possibly do it also..

If you know a good shop you can have them "Smoke test" the vaccum system. (But NORMALLY a vaccum leak will let it idle high) I say normally because a there is ALWAYS an exception to the rule. DOes this car have an aftermarket filter??

There is a large (5/8 to 1 inch hose) that hooks to the intake tubing near the TB. This is the one that runs behind the engine. This the line for the IACV. You might want to make sure its not plugged/ loose/ broken.

Thats all I can think of for now..
 

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Discussion Starter #19
air intake system is stock, original. well yesterday my brakes went out. thank god for manual transmission. anyway took undercairage plastic protecter deal off( halfway down driver side of car beacuase that was where leaking brake fluid was coming from. there are 5 or six metal lines, couldnt tell which one was leaking so tried to take the clip holding all the lines together closest to the leak, screw head broke off (rust/wetness) took a screwdriver and hammer to try and quick rig a way to get screw out. wellflathead went through clip and hit what is apparently a fuel line. so now i have gas AND brake fluid dripping out of about the same spot. long story long, are those 5 lines =3 gas, and 2 brake? oh i guess having to step on the gas pedal to get my sentra to sstart wasnt so bad haha.....
 

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You could clean your throttle body while your at it. That always helps the car idle better, especially if you buy cheap gas from walmart or whatever grocery store. shell gas FTW!!
 
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