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Cold Idle Fix

By Jim Shelden s...@wsu.edu

First, remove the Air Regulator Valve which is underneath the intake manifold:

  • Make sure you have a good source of lots-o-light. Put the car on jack stands, ramps, or a lift. You have to do this from underneath. (probably on your back)
  • The ARV has two hoses in & out and and electrical connector.
  • With pliers, push the hose clamps back, and pull off the hoses, then if you can reach ok, remove the electrical connector.
  • If you can't get the connector off, undo the two 10mm bolts holding the ARV to the intake. Then you should be able to pull down the ARV and remove the connector.
  • As soon as you can, try to see through the valve, and note if the valve is open even a sliver. (it should be totally closed)
  • Now that you're in your nice warm shop, measure the resistance across the two terminals. Should be 60 to 80 ohms. If you have a short to the case, or very high reading, you'll have to replace the valve.
  • Assuming that the valve is good, put the ARV in the freezer for several hours. Then look through it, you should see an opening between a 16th to an 8th of an inch, maybe more.
  • Now hook the terminals to a 12v source, (carefully) and watch the valve disk close. This should take 60 to 90 seconds. The coil should draw about 180ma. If it stays open even a sliver, you'll have to take the ARV apart and clean it.

To rebuild the valve, do this:

  • Remove the four screws, and carefully pull the case apart. Notice the spring and the movable phenolic plate, also look at the movable bi-metal strip in the other half of the case, it should be nice and straight. Put it back in the freezer.
  • Carefully remove the spring so it doesn't get away, then undo the nut & washers holding the plate assembly to the valve body. You'll have to remove the sealing compound.
  • Next clean the plate and the valve body with alcohol, carb cleaner, etc. Fasten the plate back on the body, hook the spring and move it a bit with your finger. Unless the plate is cracked or warped, everything should clearly move easily. I put a bit of anti-seize on the parts where the plate rides against the body.
  • Take the other half from the freezer, and look at the bi-metal strip. It should have clearly moved to one side of the case. As it warms up, it'll straighten out. This closes the ARV as the engine warms, and electrical current speeds the process up.
  • At room temp., Put both halves back together. Be sure that the tab on the bi-metal strip fits into the slot on the plate as you do this. It fits loosely, so it shouldn't be problematic.
  • Before you tighten the adjusting nut, move it a bit in it's slot and watch to see that the plate is closed over the opening. You should be able to blow a little air through the ARV when closed, but not much.
  • If you have time, (really, do this), put the whole valve assembly in the freezer. When cold, look through and make sure it has opened. Then put 12v to it, it should close in 60-90 seconds. If not, loosen the nut, and readjust, refreeze, etc., until you,re happy.
  • Under the car, hook the electrical connector. Then remount to the intake, finally hook the hoses up. Putting a little anti-seize on the valve nipples will make this easier.

Next, the Idle Air Valve:

Repairing these two valves, the IAS and the Air Regulator solves the majority of the cold temp idle and loss of power found in the Nx2K. I found that this is a tough one to troubleshoot because the engine runs well when it warms up in a few moments. The Idle Air Assembly has two solenoids on it, one called the FICD and the main idle air solenoid. It also has the idle speed adj. screw. My daughter's Nx2K had poor cold temp power, rough idle, and a rough 'miss' under light load. I checked all the usual (and easy-to-get-to stuff), but I stopped with these two valves cause they looked to be difficult. Plus the car has the ABS unit in the way. I was right about this, so take a deep breath and tell yourself your going to finish this job. The IAS is on the right side of the intake chamber, and it's a bugger to get at. I had to use two drop cords to get enough light. Here's what you'll have to do:

  • Lift up the PS fluid tank out of its holder so you can push it a bit out of the way. Also undo the clamp holding the AC hoses, and remove the oil filter. You'll never get your fingers in here if you don't do this.
  • Undo the connectors from the FICD solenoid which is the one sticking out from the side. Pull off the metal bracket on this connector- you don't need it and it really gets in the way. Put a wrench on this and then unscrew it by hand from the assembly. You'll have to fish the wires and connector around and around, being careful not to stress the connections. As the solenoid comes out, go slowly so that you don't lose the spring and plunger. In fact you might want to put something under the car, so when you drop this stuff, (I did) it doesn't get lost in the dirt.
  • Remove the (4) 10mm bolts holding the IAS. You'll have to use a 1/4" drive and socket, and really strain your fingers cause it's so tight. Once the IAS comes out, disconnect the main solenoid. The gasket will probably self-destruct, so clean it off of the intake.

Now rebuilding the IAS:

  • Put 12v to the main solenoid and watch that it moves the plunger ok.
  • Screw the FICD solenoid back in and test it the same way. If either solenoid doesn't work, you probably have to replace the whole assembly. I doubt that you cam buy either solenoid alone from the dealer.
  • Assuming that the electrical function is good, clean the whole thing. I used carb cleaner to flush out most of the carbon. Next, use a Q-tip and carb cleaner or acetone and clean the air passages, springs, and plungers. You should unscrew the idle adjusting screw and clean all that as well.
  • Leave off the FICD solenoid, but put the idle adjusting screw back. Put a bit of gasket sealer all around the assembly, but not too much! You don't want to plug up any passages. It's amazing how sensitive the engine is to the proper function of the IAS.
  • I'm a believer in using anti-seize on all threads, so put some on the four bolts. Screw things back together by hand as much as possible. Be careful not to cross-thread the aluminum intake! Evenly, tighten all four bolts with the socket.
  • Re-hook the electrical connectors, and carefully screw in the FICD so that the spring & plunger do not' fall out. Now put the oil filter back in, or do a complete oil & filter change.
  • If you are certain that the oil is ok, and everything is connected, start your engine. Your going to have to adjust the idle speed screw until you are happy with it. This may take some tweaking to get it right.
  • Try the AC while idling, the FICD should increase the idle to compensate for the increase load.
  • Put the AC bracket and the PS fluid tank back in place. You should be ready to go....