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Rough idle when cold - Running rich


Pochie45566

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I am going to arm myself with a can of carb cleaner and go vacuum leak hunting. I have replaced the PCV valve and hose, the old hose had cracked and was falling apart. If I'm correct, a vacuum leak after the throttle body causes low and lumpy idle. Before it causes a high idle. So I am most likely looking at oil pan gasket, dipstick, front seal, stuff like that. Also going to check out the charcoal canister. 

Would the carb cleaner trick work down on the oil pan? I don't see why not just making sure. 

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If the AAR valve is only open a sliver when cold then it is not working properly. The thermotine switch is a ground for the AAR so it has to work correctly . Do not put AAR in any water . The AAR should be fully open when cold and close slowly with voltage . Ohms tests with the EFI bible will show this. 

Sounds like you also have a vacuum leak

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5 minutes ago, Pochie45566 said:

I am going to arm myself with a can of carb cleaner and go vacuum leak hunting. I have replaced the PCV valve and hose, the old hose had cracked and was falling apart. If I'm correct, a vacuum leak after the throttle body causes low and lumpy idle. Before it causes a high idle. So I am most likely looking at oil pan gasket, dipstick, front seal, stuff like that. Also going to check out the charcoal canister. 

Would the carb cleaner trick work down on the oil pan? I don't see why not just making sure. 

Disconnect your brake booster and purge canister also looking for vacuum leaks 

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1 minute ago, madkaw said:

If the AAR valve is only open a sliver when cold then it is not working properly. The thermotine switch is a ground for the AAR so it has to work correctly . Do not put AAR in any water . The AAR should be fully open when cold and close slowly with voltage . Ohms tests with the EFI bible will show this. 

Sounds like you also have a vacuum leak

It runs the same without the thermo time switch plugged in. The switch doesn't seem to be working anyway, the contacts are quite corroded and every sensor in that housing is new except the switch. But wouldn't that only prevent it from closing not opening? The problem here seems to be not enough air at idle. On the average morning when I pull the AAR out it is only a sliver open. Once I throw it in the freezer it is about half open. 

My AAR reads 60 ohms for the heater, which is what is labeled on the unit itself

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The thermotime switch is on the circuit for the cold start valve.  But the AAR shows a ground through the ECU, pin 34.

1 minute ago, Pochie45566 said:

On the average morning when I pull the AAR out it is only a sliver opoen. Once I throw it in the freezer it is about half open. 

Both madkaw and myself have mentioned that the AAR should be more open than a sliver.  I can't remember what it looks like but Nissan provided a drawing.  Pinch that hose when it's cold.  If it splits fix it with a piece of heater hose.  Then you'll know.  But you still have vacuum leaks.

image.png

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12 minutes ago, Pochie45566 said:

On the average morning when I pull the AAR out it is only a sliver open. Once I throw it in the freezer it is about half open. 

Per the instructions I copied, your AAR is out of adjustment.  Adjust it so that it is open on the average morning.  It moves, which is good, but it's starting from the wrong spot.  And you still have vacuum leaks.

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I followed adjustment instructions from this website, http://www.hiperformancestore.com/Ljetronic.htm, and put it back on the car, idled much better but idle got too high after a while because it was not closing. I had my idle sitting at about 1000 when cold which is where id like it if not a bit high. But once I was up to temperature, the AAR was still open about half way. Going to apply 12 v I know is good then see if it closes then. 

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16 minutes ago, Pochie45566 said:

 Going to apply 12 v I know is good then see if it closes then. 

The AAR has 12 volts at all times when the engine is running.  You could put it on a switch if you want to test it as it's supposed to work.

Have you tested for continuity to the AAR plug from pin 34 at the ECU?  Maybe the ground circuit is missing.

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I think you need to just open your wallet and get another AAR valve. I didn’t know you could adjust them, but yours does not seem to be working correctly. It sounds like there isn’t proper movement of the valve - as in , not enough, which might not be adjustable . 1000 rpm cold is not too much- if not enough really. 

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