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Discussion Starter #1
Anyone know which fails first, the actuator assy-ascd (nissanpartsdeal # 18910) or the pump-vacuun ASCD (nissanpartsdeal #27084P)?

I injured my right leg driving almost cross country from a marathon in 1990. A nerve involved with gas pedal control. It didn't heal until I started using the Altima cruise control. I love the cruise control and use it often.

The speed control was very good until lately. Now I'm cruising at 55 mph, steady speed, engage the cruise control and the speed goes up 5 mph then the acceleration stops abruptly. The velocity seems to hunt, high, low, high, low. It never use to do that. In the past, cruising at 45 or 55 I'd engage and it would maintain the speed. Perhaps not in cold weather, as in cold weather it seemed to take longer to find its speed but once in, it worked fine. Driving without cruise control, it seems okay. I can manually maintain a steady speed.

I see the pump-vacuum is a 4 wire device and wondered if it's a stepper motor controlled by the ECM.

I saw there was a slight crack in the hose from the pump-vacuum to the actuator assy so I taped it up and used silicon to fully seal the hose to the actuator. Didn't fix the problem.

I'd appreciate it if anyone who's encountered this problem and found a solution would post. Thanks

BillJ
 

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09 Altima 3.5SE 6MT Sedan
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maybe replace all the vac hoses in the system before you go crazy replacing actual parts...which at two and half decades will no doubt be challenging! Hose is cheap, standard and easy to do. Check the ID (interior diameter) and grab a few yards from your local supply. The hose, a pair of scissors, some pliers and a beer should be all you need.
 

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Discussion Starter #3
Taking your advice Doug, I found some 4.8 mm fuel line that fits perfectly. Found the old just a bit frayed at the vacuum pump end that I previously missed.

Also, ordered some 4 mm silicone vacuum line to replace the EGR solenoid tubes that might address some performance issues. Will get back to you in a few days after I see how it runs. Thanks.
 

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Discussion Starter #4 (Edited)
Drove it today with the replaced vacuum tube. Still the problem. Seems like it keeps accelerating then drops quickly when way above. I seem to recall two springs somewhere, on the throttle body? Then I considered that just driving it's okay. Thinking about it I remembered the cable covering was a bit damaged over the years. I looked when I got home and where the cable rounds the bend over #1 intake, the plastic was gone and the metal coil showed a bit of rust discoloration. The effect is like a speedo cable that has worn and parted a single strand. If a strand has parted, it's catching and resisting return. This what I think is the problem.
 

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Discussion Starter #5
Taking your advice Doug, I found some 4.8 mm fuel line that fits perfectly. Found the old just a bit frayed at the vacuum pump end that I previously missed.

Also, ordered some 4 mm silicone vacuum line to replace the EGR solenoid tubes that might address some performance issues. Will get back to you in a few days after I see how it runs. Thanks.
Replaced the 4mm EGR solenoid vacuum tubes and the car is running like a champ. I had a piece of hard PVC tubing on one of the ports to another. That passed near the EGR. When the EGR valve was passing exhaust and heating, the PVC got soft and collapsed. I notice later models of the EGR solenoid have both tubes on the 2 port side, facing in the same direction while the 1995 and earlier have the 2 at 90°. This routes the tube a little more away from the EGR. Thanks for the advice.
 

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09 Altima 3.5SE 6MT Sedan
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Yeah! We're calling this a win and cheap one at that! Here's to a few more years of troublefree motoring!
 

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Discussion Starter #7
Found another problem when it started misbehaving again - having used anti-seize compound on the EGR valve pedestal the rear nut came loose and was allowing air in. Since repaired but another problem so a new post...
 

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Discussion Starter #8
So, after fixing the vacuum leak under the EGR valve I was still having some difficulties. The cruise control was working just fine. But I would get occassional mis-fires and my mpg was low. The code reader would show I'd fail an emissions test but no codes were setting even though some of the leds on the code reader were orange instead of green. I tried a mid-octane instead of premium. Also I had changed out a bad fuel injector some time ago but only one. I half decided to change out the other 3, then replace the EGR and eventually the front O2. But I checked my hoses again. All the 'vacuum' hoses had been changed except for the BPT lower hose as its port was larger than my new hose diameter. It seemed stiff. It sees exhaust pressure not a vacuum. So, I changed it out forcing the newer hose on. Car seemed to drive better. That was maybe a week ago. I decided to check codes today. Lo and behold every led was green, no would fail emissions led and no stored codes! I'm happy.
 

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09 Altima 3.5SE 6MT Sedan
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:)

Mental note...nissan vacuum line lifespan = 23 years.
 
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