# Engine cuts out @ 2300rpm



## sk88er44 (Aug 18, 2010)

Hey everyone,

I have a 1993 Nissan Sentra Classic (pretty much a 1989 made in mexico until 1993, so it's got a b12 engine)

I'm running into this problem where the car runs perfect, then suddenly it will bog out, and then won't go past 2300rpm. After it sits, or if I drive under that rpm for a bit, the motor will open back up and then im good to go.

I brought it to the dealership (i know i know... sooo expensive), and they seem to think that it's the IAC valve (idle air control). Problem is this part is ridiculously hard to find, apparently it's back ordered in Japan for a few months.

Has anyone here had to change that valve before? I'm trying to find a used one, or even a new one at this point

Thanks 

Steven

Bolton, Ontatio


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## heathman (Sep 13, 2010)

With any drivability issue, I would start by scoping your oxygen sensor to see how it is fueling the vehicle..It works on a 1 volt scale and should rapidly change from.1 to .9 volts rapidly when engine is HOT and reved..take it for a drive with the oxygen sensor hooked to a fast multimeter or a vantage..etc..to see how it operates on the road under load. ... It could be an oxygen sensor stuck leanor rich.... I bought a pathfinder and the guy said it needed an IAC, and he couldn't afford the 500 dollars and sold it to me.... I scoped the oxygen sensor and found it to be stuck lean resulting in an overfueling situation afecting the base idle.... Good luck !!


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## smj999smj (Jan 1, 2006)

Having worked for Nissan for many years, I can't say that I ever replaced one on a GA16i motor, which is what I assume you have in your car. It would actually be called an AAC valve (auxilary air control) and would also incorporate the FICD (fast idle control device) and the idle-up solenoid, I also don't like it when you have a car diagnosed and they say they "think" that's what the problem is. It sounds more like a problem with the ignition module inside the distributor heating up and failing by your description, but not having worked on the car, we can only go by what the dealership says at this point.


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## sk88er44 (Aug 18, 2010)

Thanks guys, I'll mention that to my mechanic, as I don't have the tools to do this @ the moment (just moved)

should mention that I changed the oil, air and fuel filter, distributor cap, rotor and coil. It also has new wires and plugs. Obviously this did not fix this problem  but never hurts to give the motor a refreshing

man these valves are a nightmare to find


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## fairlanephantom (Feb 3, 2010)

Is it fuel injected? I still have extra sensors I'm not using anymore. At the very least, I have two b12 map sensors a spankin new vacuum control module direct from Nissan two years ago. Thing was $500 new.

I had your problem once. It was my carburetor.


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## sk88er44 (Aug 18, 2010)

fairlanephantom said:


> Is it fuel injected? I still have extra sensors I'm not using anymore. At the very least, I have two b12 map sensors a spankin new vacuum control module direct from Nissan two years ago. Thing was $500 new.
> 
> I had your problem once. It was my carburetor.


Wow thats alot of parts lying around  doing anything with them?

And yes it's fuel injected. I just picked up a haynes manual and have been reading through it.

My motor has TBI (Throttle Body Injection). From what this manual shows, it looks like what they call the "Idle Speed Control (ISC) valve", could be the IAC (idle air control) valve.

Do you guys know if they are the same thing? I'm loving this car so far, and I want to get this fixed so I cause any further problems with the motor

Thanks


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## fairlanephantom (Feb 3, 2010)

Lot of parts, just in a box because it doesn't use them anymore. 

Never messed around with TBI, hope find the part. Check car-parts.com. It'll show was scrap yards in your area might have it.


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## sk88er44 (Aug 18, 2010)

You interested in gettin rid of them?

And thanks that website is great, unfortunately this car isn't too common in my area, which i now know


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## bob89sentra (Sep 15, 2005)

This screams of MAF,
check the computer codes, if the MAF (Mass Air Flow) sensor was intermittent, the computer will limmit the RPM's to right around 2,000 RPM. 
The computer would have a code stored showing the MAF as a issue.


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## fairlanephantom (Feb 3, 2010)

sk88er44 said:


> You interested in gettin rid of them?
> 
> And thanks that website is great, unfortunately this car isn't too common in my area, which i now know


Yeah, I'm selling everything I don't need anymore. I like my car, but I'm not attached to every last piece of it.


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## smj999smj (Jan 1, 2006)

Could be MAF (or "hot wire modulator," as the Nissan parts book will call it), but usually when they fail on these cars, it's not an intermittant issue and will run bad at all times. Nissan service manual refers to the parts as the AAC valve (auxilary air control valve). The problem is terminology tends to be inconsistant between factory service manuals, parts catalogs, and non-factory service manuals, so one part can be called several differant names. The AAC valve, idle speed control, and idle air control are all terms used for this part.


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## bob89sentra (Sep 15, 2005)

smj999smj said:


> Could be MAF (or "hot wire modulator," as the Nissan parts book will call it), but usually when they fail on these cars, it's not an intermittant issue and will run bad at all times. Nissan service manual refers to the parts as the AAC valve (auxilary air control valve). The problem is terminology tends to be inconsistant between factory service manuals, parts catalogs, and non-factory service manuals, so one part can be called several differant names. The AAC valve, idle speed control, and idle air control are all terms used for this part.


I have seen the MAF do that, but with the AAC I only have seen problems at idle. The AAC, FICD, and Idle up solenoids are there to increase amounts of air going into the engine under circumstances where there is more load like A/C, power steering, and when the engine is colder to help suppliment the wax pellet filled cold idle cam. Even if they all were stuck closed, or unplugged the engine still runs (I have done it) the big drawback is it does not want to idle unless you open the warm idle adjust screw.
The other things that comes to mind with those symptoms are a spark coil, or IGN module going on it's way out.


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## blownb310 (Jun 10, 2002)

I agree with Bob. The MAF sensor would be first on my hit list for this problem. I've changed a few back in the day.

Mike


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## sk88er44 (Aug 18, 2010)

hmmm... thanks for the replies guys, I'm gonna look into the MAF

smj999smj said that usually MAF problems are constant. The thing with my car is when its not acting up, it runs like a little sports car, then it bogs out randomly

also it seems that lately it doesn't want to stay running when the engine is cold, sputters like no tomorrow

Once it warms up, it'll run fine (aside from the previous mentioned 2,300 rpm problem)


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## sk88er44 (Aug 18, 2010)

So I ordered a IAF valve and an oxygen sensor, so I'll let you guys know how that goes. Should be here on tuesday


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## Crazy-Mart (Jul 14, 2002)

MAF sensor X3 .... changed a few on the E16i... your canadian 93 is actually an e16 engine ... got a whole TBI here without maf taught ... ill have to look further cuz i doubt ive sold it yet


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## sk88er44 (Aug 18, 2010)

Crazy-Mart said:


> MAF sensor X3 .... changed a few on the E16i... your canadian 93 is actually an e16 engine ... got a whole TBI here without maf taught ... ill have to look further cuz i doubt ive sold it yet


Can you please look into this? I need this fixed asap as this is my car i drive to work every day

thanks


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## sk88er44 (Aug 18, 2010)

I'm loosing my mind trying to find this IAC valve lol

The Haynes manual calls it an ISC (idle speed control) valve

In the following pictures, is this the IAC valve??

Thanks 

http://sphotos.ak.fbcdn.net/hphotos..._433224438405_505078405_5079427_4814564_n.jpg

http://sphotos.ak.fbcdn.net/hphotos..._433224423405_505078405_5079426_6951497_n.jpg

http://sphotos.ak.fbcdn.net/hphotos..._433224238405_505078405_5079413_2225447_n.jpg

http://sphotos.ak.fbcdn.net/hphotos...9_433224168405_505078405_5079411_169683_n.jpg

http://sphotos.ak.fbcdn.net/hphotos..._433224423405_505078405_5079426_6951497_n.jpg


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## bob89sentra (Sep 15, 2005)

In the 2nd picture that is a ISC valve. I am positive that it is not your issue though, your problem is either in the IGN circuit, or in the MAF. 
Anyhow you can take some carb cleaner and clean up the passages on the ISC, and ensure proper flow. Also you can jumper the valve to 12V and verify that it clicks open and closed properly.


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## sk88er44 (Aug 18, 2010)

bob89sentra said:


> In the 2nd picture that is a ISC valve. I am positive that it is not your issue though, your problem is either in the IGN circuit, or in the MAF.
> Anyhow you can take some carb cleaner and clean up the passages on the ISC, and ensure proper flow. Also you can jumper the valve to 12V and verify that it clicks open and closed properly.


When I took the ISC valve off, I got my friend to turn on the ignition and the valve just vibrated. Is that because it's stuck? or because it's opening and closing very fast?


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## bob89sentra (Sep 15, 2005)

It could be stuck, though the computer does flutter the valve while it is running to change the amount of flow. Try blowing through the passage with it on and off you should be able to notice a difference in flow from one state to the other.


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## sk88er44 (Aug 18, 2010)

You mean blow into the valve with the car on and off?


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## dreamteam (Jul 29, 2005)

*bog*

Sounds like a MAF, here's a few more to think about.
Plugged cat or restricted exhaust.......alternator weak and or bad battery connections.......fuel delivery, as in plugged filter, low fuel pump pressure,restricted fuel line.


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## bob89sentra (Sep 15, 2005)

sk88er44 said:


> You mean blow into the valve with the car on and off?


Yes, with the key on and off. I usually just unplug the sensor, and jumper it to the battery to eliminate any other confusion though.


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## sk88er44 (Aug 18, 2010)

Hey everyone, thanks for all your help 

Good thing I didnt do what the dealership said and buy an IAC valve, as it was not the issue. I ended up buying an entire parts car with an GA16i motor in it, and one by one, changed parts till the issue was resolved.

It ended up being the "air flow meter" as the haynes manual calls it. Is this the same as the Mass air flow sensor that you guys were talking about?

Once again, thanks alot  Definitely going to be using this forumn alot

Steven


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## blownb310 (Jun 10, 2002)

You're welcome Steven, and thanks for following up and letting us know. Too many times people don't bother to follow up and many threads go cold with no result. 

Glad you got to the bottom of it. 

Mike


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