Okay, I still have this problem with the idle, and now engine is running cold. For about a month now my Max has been idling around 2000 rpm most of the time. When it gets hot, it will go back down to 7-800 rpm. Problem is when I turn it off, and restart it it goes right back to 2000 rpm, like its taking forever to heat up. Now, when I went to work the other day (35 mile hwy trip), the temp gauge barely gets above the letter C on the dial, not even close to the needle being horizontal(normal temp range). Any idea what this could be? I just replaced a bunch of studs, so I had to drain my radiator and refill, but the idling problem has been for a while now. Also, I posted on here before about the running cool problem, and someone stated to remove the air bleeder screw on top of the manifold. When I pulled that and started the engine, coolant started flowing out of it, so my guess is that it is not air trapped in the system. Thanks in advance for any help.

 

It may be that your thermostat is stuck open. That is a possibility. As for it running at 2000, I would look at the IAC valve. If its not that then its probably caused by the temp problem cause the comp sees that its not at operating temp and is trying to get it there by keeping the engine at high rpm.

 

Okay, changing the thermostat cured the running cold problem, but the idle problem still exists. This is driving me crazy, I have replaced plugs, wires, rotor, cap, still no luck.

 

try cleaning the IAC valve.

 

Clean IACV as stated, test cold bypass valve operation: take it off (clamp hoses first), put in kettle of boiling water and observe.

btw. +20C about +72F

 

Can you clarify. So I pull it off and put it in a pot of boiling water to see if it opens? I have it off now, and at room temperature or with cold water it is partially open like in the picture. When I put hot water on it it appears to close. I am assuming that this means it is working correctly? The little round shaped thing that sits in front of it was pretty nasty, had lots of carbon deposits on it. I cleaned it up, could that have been messing up the idle?...

 

Cleaned everything now its worse. Now it is a surging idle. It goes to 2100, drops to about 1800, then immediately surges up to 2100 again, doing this about once every second. ????

 

pcv valve?

 

Cleaned it, haven't replaced it yet though.

 

hmmmmm......then maybe check the TPS or MAF, and maybe even the O2 sensor. Although it could still be a malfunctioning IAC.

 

any body eles have any other ideas

 

The thingie flap seems to work as it closes warm. If idle got worse, you have now got a tiny air leak in somewhere the IACV system u opened. Leak could be between those opened blocks, or maybe the thick hose feeding the IACV from intake tubing.

I dont think that (without hammer) one can cause any other problem than airleak when cleaning IACV. Pretty trivial job. But really very small leak will cause problems.

The FSM tells for nissan mechs NOT to open the IACV. That is all right -lol- for them. But it also tells how very tiny leaks might ruin the idle.

I would clean, try some liquid sealant between all IACV parts, even on the supply hose connections. For troubleshooting try spraying something while engine is idling, water, oil or 'anything'. When your spray hits the leak, idle will be corrected temporarily as the airleak is blocked for a moment. If this problem persist, I would also inspect that all IACV aluminum blocks are not warped in any way, so that the bolts can really tighten the assy.

Second issue:
I suppose one or many of the V6 small hoses in air supply /vacuum system causes high idle. Go through all tiny hoses, take out and inspect for craks. Note: There are lots of hoses... For test purposes block the PCV hose temporarily.

 

In park or neutral, mine will "surge" up and down from like 1400-1700, but not with the A/C on (It will still be to high though, like around 1200). When I pull back into gear, it will drop to around normal, a little high though.

I replaced my 02 sensor recently, but could I have the same problem? Sometimes it'll idle normal - like around once a week during a drive. I don't know, it's weird.

I'll follow these directions and see what helps.

 

I had similar condition after disconnecting and reinstalling the idle feeder tube. The tube was correctly in, but possibly did not seat properly. Small hose turnup with pliers (maybe 15% degrees) corrected the rEALly tiny leak, and idle has been ok since that...

see the small IACV feeding hose, blue dots
clic: http://www.cardomain.com/memberpage/748507/4





Note1.: I'll test (today?) that how idle behaves after disconnecting that hose alltogether.

Danger Note2.: In the pic is seen gas pedal wire & cruise ctrl wire to throttle body TB. Someone noted that as these wire rubber seals get ripped, they might get loose and jam the throttle open. That is dangerous situation! As/If u have these rubbers worn, either rip all off, or wrap them closed with self vulcanizing rubber tape, AAND lubricate the wire.

 

Empirical tesTing: disconnection of that idle airhose results in immediate engine dying off on a healthy engine. With throttle opened functions 'without any' problems.