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Discussion Starter · #1 ·
the haynes tells me to run the engine to warm, then backprobe one of the terminals of the AAC and that i should see 4v-8v dropped. was wondering if you did this before, cause im not sure im doing it right. im backprobing with the (+) probe and grounding the (-) probe to ground... this correct? cause i'm showing a full 13...volts. also, i think i remember if you unplug the AAC while the engine's on, you should hear some change in RPM.... but i dont hear any difference now. hayne's says if the above volt test dont work, to have the ECU inspected... hmm... or i wonder if my AAC is bad?

been having loping/slightly rough idle, and so far i've come to this... although im still looking for something else that might be causing it to not work.

any ideas?

just replaced:
some hoses - no leaks that i can tell.
fuel injector - no leaks external or from O-rings
PCV valve
plugs - NGK (show slight whitish color, base is dry black)
Oil flush
 

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Mofo
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Try manually pulling the error codes from the ecu. That should help, if there is a code stored. Cause the way it sounds your check engine/ service engine light isnt on.
 

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Cleaning my IACV helped stumbling and hesitation, but idle was OK otherwise. My problem was carbon build up. It is easy to remove on this car, to check, or clean. I posted pictures of the cleaning and the test for resistance. Not familiar the procedure from Haynes. I used Alldata. Don't know that a bad IACV will set a code. Mine did not set a code, but it was only dirty. Do a search for what I did. Maybe it will give you some ideas
 

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it will not set a code if it is bad all the time. Mine didn't. It's a $135 part. If you really think it's bad, it's easy to replace. 2 Screws.
 

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Discussion Starter · #5 ·
christ, $135? -_- well, i cleaned it out but it didnt help. the idle was loping before but seems to have stopped. but the idle still feels rough.

normally, if you unplug the aac, does the idle change?
 

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Discussion Starter · #6 ·
well loping is still there, bounces between 600 and 900. resistance test checks out, the voltage back probe i havent done, since haynes doesn't really make it clear which wire to test, and i dont wanna test the wrong one and end up screwing something up. the idle is supposed to change when you unplug it, and i get no change what-so-ever. not sure if its the aacv or knowing my luck, the ECM/ECU. oh well.

i might get another aacv for the hell of it, any brand i should/shouldn't get? the store listed several on their comp (bosche makes one, but i think i should stay away from em given their rep with the sentra). i might also just try grabbing one from a JY.
 

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absolutely classic
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Solidox2k said:
well loping is still there, bounces between 600 and 900. resistance test checks out, the voltage back probe i havent done, since haynes doesn't really make it clear which wire to test, and i dont wanna test the wrong one and end up screwing something up. the idle is supposed to change when you unplug it, and i get no change what-so-ever. not sure if its the aacv or knowing my luck, the ECM/ECU. oh well.

i might get another aacv for the hell of it, any brand i should/shouldn't get? the store listed several on their comp (bosche makes one, but i think i should stay away from em given their rep with the sentra). i might also just try grabbing one from a JY.
Did you clean the Throttle Body? I mean really clean it so all the smaller holes are clear. If not, I would try that, it may help with some of your problems.
 

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Discussion Starter · #8 ·
Kindfiend said:
Did you clean the Throttle Body? I mean really clean it so all the smaller holes are clear. If not, I would try that, it may help with some of your problems.
well, true, i never tried really cleaning it out. i just cleaned out the chamber and plate. i checked it already, rather clean, but then again i never tried cleaning out all the smaller holes... mainly cause i didn't wanna bother with ordering the gasket and waiting.... but i'll try it when the car gets back.

i left it with a small shop to do just a diag on it.... not really my idea, but there's no arguing (sp?) with my pop who insisted. his money, so~..... i just hope they dont screw it up or something...or just retard the timing instead of finding the real problem. my pop knows the guy, but i dont.

thnx for the advice, gonna see what happens. if i find a solution i'll update (lot of search results on idle probs end with suggestions, but only a few update and say what fixed it, or if it got fixed.).
 

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Respek Knuckles
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look in the fsm.
 

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Discussion Starter · #10 ·
krylonkoopa said:
look in the fsm.
ok, i've been seeing this abbreviation for a while.... didnt ask cause i didn't wanna sound dumb, but.... FSM = Factory Service Manual ????

isn't that the same they use at the stealership? expensive?
 

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Discussion Starter · #13 ·
hey, after i remove the TB to clean it, am i going to need to put any sealant with the new gasket, or can i just torque it on dry???
 

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MY PIRANNAS ARE BITTING
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Say ya I've been searching for weeks now trying to get to the bottom of this stalling my car has once I'm driving and coming to a stop or slowing down, I push in the clutch to down shift when my rpms goes up and stays there for a lilthen drops. Sometimes it goes up and down, up and down when coming to a stop or when slowing down with the clutch in. I've cleaned the IACV, heck I've even tried the one my cuzin has on his 200sx still same thing happen. Next I've check the vacuum lines all where fine, push the egr up and down to see is the car bogs and it almost died so I guess is not sticking. Clean the tb several times already within the last 2 months thinking that was the problem.
I've yet to check the timing with a gun ever since I put in a UR pulley do ya think that might be the problem. I didnt want to ask at first thats why I've checking the old threads and post but still the car does this, any input on this will be helpful, NF nerds? j/j
 

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absolutely classic
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off_da_meter said:
Say ya I've been searching for weeks now trying to get to the bottom of this stalling my car has once I'm driving and coming to a stop or slowing down, I push in the clutch to down shift when my rpms goes up and stays there for a lilthen drops. Sometimes it goes up and down, up and down when coming to a stop or when slowing down with the clutch in. I've cleaned the IACV, heck I've even tried the one my cuzin has on his 200sx still same thing happen. Next I've check the vacuum lines all where fine, push the egr up and down to see is the car bogs and it almost died so I guess is not sticking. Clean the tb several times already within the last 2 months thinking that was the problem.
I've yet to check the timing with a gun ever since I put in a UR pulley do ya think that might be the problem. I didnt want to ask at first thats why I've checking the old threads and post but still the car does this, any input on this will be helpful, NF nerds? j/j
Yeah, I had this same problem. I couldn't find it either and I cleaned the IACV, throttle body, EGR, timing to 13*, and I could not figure out why the car did that. Only did it when it was warm though. The only thing I could think of that I didn't replace was the throttle cable. Try taking it off and letting WD40 run through the inside and see if it changes anything. It's cheap and you may get lucky.

Solidox2K: I didn't use anything on the gasket, there didn't look like there was any old RTV on there anyway. Sealed up fine and didn't leak as far as I could tell listening with a length of hose.
 

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MY PIRANNAS ARE BITTING
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N.e. 1 else? Still cant figure it out when driving my car and when slowing down or coming to a stop and I push in the clutch thats when the idle starts to go up then when I seem to release the clutch the idle drops. Searching for weeks now, clean everything imaginable from IACV(even tried a different one), replaced the PCV, clean TB, ckd all vac lines replaced 1 that looked funny, spark plugs, cable, dist cap, only thig is I cat pull off the old rotor after uscrewig it? Could I blame this o the rotor evethough I have o prob startig my car? I kow theres a billion of post covering this but It hasnt help me out as of yet.
 

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OK, let me take a stab at it. I go to a Saturn forum, and one of the Techs had a great explanation of how the IACV, PCM, and Throttle Position Sensor interact. I know it may be a little different on a Nissan, but I am thinking they use similar principles.

The IAC valve is a step motor and will hold the last postion commanded by the PCM until it is commanded to do otherwise. It ONLY comes into play (varies adjustment) when the PCM recieves a signal from the TPS (Throttle position sensor) that the throttle is closed. It will then make gradual and incremental adjustments based on PCM commands in (in responce to whether the car is still moving etc..) to maintain proper idle or deceleration throttle (idle) speed settings. It is this behavoir that keeps the idle speed UP on manual cars when the car is MOVING and likewise performs a similiar function on the automatics (if the car is MOVING and the shifter is placed in nuetral) The valve (IAC) itself is NOT a simple solenoid, it is a step motor, capable of many incremental adjustments between wide open and fully closed. The airflow through the IAC even at off idle throttle postions is actually there to help PREVENT hesitation. Hesitation indicates a problem with fuel enrichment or poor ignition.
It may be good to check the Throttle Position Sensor. Easy to do on a 93 Sentra with the 1.6 motor.

1. Disconnect throttle sensor connector.
2. Using an ohm meter, check resistance across terminals A and B. Resistance value should change smoothly, without any glitches, from approximately .5 to approximately 4 ohms as the throttle is moved from idle to Wide Open Throttle (WOT). Replace sensor if it fails the above test.

There is probably a picture of this in the B14 FSM to show terminals A and B.
 

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MY PIRANNAS ARE BITTING
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Catman said:
OK, let me take a stab at it. I go to a Saturn forum, and one of the Techs had a great explanation of how the IACV, PCM, and Throttle Position Sensor interact. I know it may be a little different on a Nissan, but I am thinking they use similar principles.



It may be good to check the Throttle Position Sensor. Easy to do on a 93 Sentra with the 1.6 motor.

1. Disconnect throttle sensor connector.
2. Using an ohm meter, check resistance across terminals A and B. Resistance value should change smoothly, without any glitches, from approximately .5 to approximately 4 ohms as the throttle is moved from idle to Wide Open Throttle (WOT). Replace sensor if it fails the above test.

There is probably a picture of this in the B14 FSM to show terminals A and B.
Thanx for the knowledge, now I gotta go out and get me one of those dam meters. BTW my ride is a 99 1.6 and yes I know it should be the same :rolleyes:
 
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