sparky1562

I took the TB and the IAC off, cleaned them, but them back with new gaskets, cleaned the MAF with MAF specific cleaner ant let it dry. Did not change anything else. (Did not remove the plungers, yet).

Before, the idle would drop to 550, surge a alittle to 1000, stumble back to 550, etc. Now it idles smooth, I adjusted the screw on top of the IAC a little bit, slowed the idle down from 1100 or so to 750. Then for some reason, with out me touching anything, it jumped to 1600 and stayed there. I but it in gear, back in park, still there. Turned the ignition off, back on, started up and idled at 900 or so. Stayed there for 10 minutes. Shut it down, later ran some errands, when I got home, put it in park, idle went to 1600 again!

Shut it off, restarted it right away, idled at 900 or so!

What does this sound like?

I checked the gaskets by spraying carb cleaner all around them, no leaks. Checked all electrical connections, all tight.

If I pull the valves out of the IAC, are there O rings that need to be replaced and what size/where do i get them? Dealer says it is not servicable!

andrei3333

Thats it kinda weird, it should not jump to 1600rpm randomly like that, if it was a vacuum leak problem, or an improper gasket, it would always idle badly, not sometimes. I would not spray my maf with anything, but i think your maf is also fine because again it does not always idle at 1600.

Im not really sure right now why it would idle like that sometimes and not always, i think thats the key to your problem.

Also, what o-rings are you talking about here specifically ?

sparky1562

The Haynes manual talks about an O ring that is internal to the IAC assembly, on the plunger side. It does not give a picture. I assume if you take the actuaters out, that is what they are talking about. I have read in the other IAC thread that you should take these apart and clean them, but I don't want to do it with out knowing if there is an O ring in there that must be replaced.

I am going to start checking sensors this morning. I checked every hose I could, did not find any loose or leaking. Stumped at this point. It runs smooth and excellerates great, Just keeps getting this high idle issue.

andrei3333

So the dealer said you cannot buy it separately huh, yeah and that means it comes together with a brand new IACV assembly.

I really cant suggest anything here, when i cleaned my iacv i did not take it apart, i sprayed and cleaned anything i could from the inside into the wholes that were there. the idle is good now, so i dont know if you should take it apart .

i know a guy on here who recommends taking it apart and he never mentioned any o-rings that needed to be replaced. wait until more users give you their opinions on this.

KRRZ350

iTrader: (29)

Are you getting an iacv code yet?

sparky1562

No. No codes. Just did diagnostics on the IAC valve, the MAF, the TPS, and working on the engine coolant temp. All in normal range so far.

Question: The thermal plunger for the high idle that is part of the TB. Manual says it should extend when at operating temperature. Starts at short mark on cam, ends up on high mark. Mine does not seem to move much, definelty does not get to high mark. The trottle does not seem to close all the way, or at least it is not impeded by the high Idle cam, if I force it to the high mark (defeat the spring), and it does not hit the stop on the throttle arm (still at factory set mark - I have not changed it). Would this cause any of this symptom?

sparky1562

Okay, I am sure it was the fast Idle cam and the thermal plunger on the side of the TB. From hot to cold, the piston coming out of it moved maybe 1/8" at best, not enough to move the trottle off the high part of the cam. I ajusted so that it is out of the picture. Not sure what this will do when the engine is cold.

It was fine until the engine got to operating temp, then the engine sped up! I guess once the coolant temp sensor got hot.

Before I go taking it apart, has anyone done that before? How far should it move from cold to hot?

sparky1562

Anybody? Anybody? Bueller? Bueller?

Double E

You're talking about the round plastic piece inside the IAC that comes to a point in the center right?

I completely disassembled it, it only had 1/8th of travel before & after I took it apart. it is driven by a small, yet very strong spring inside. I found no debris inside it when I took it apart also. There were no O-rings inside and if there were any I failed to recognize, they were able to be re-used.

In general, I found no reason to recommend taking the IAC apart further than removing it from the IM, cleaning carbon/soot from behind the brass cap (3 phillips screws) and cleaning the rest of the entire unit well.

sparky1562

No, I am talking about the high idle cam, which cracks open the throttle when the coolant is cold. I can't figure out how to attach a picture, or I would!

It is on the same side as the throttle/cable, front side, just below the throtle. It is supposed to move out as the coolant gets hot, moving the throttle to the low cam position.

Thanks for any help!

humaras

gents,
i have a 97 maxima with 90K that is exhibiting the same symptoms. The idle would be smooth, around 750 but after driving for a bit from time to time it would spring up to 1500 or 1600...but that would be the idle in P or N, but if i bring the car in gear into D, it would drop down to 800 or so. This annoying symptom has been going on for about 2 years now. I just left it alone and it is more pronounced only in the colder parts of the year.

So I read one of the posts about resetting the idle--and I did that about 3 days ago...so far so good, I unplugged the maf sensor, and the idle was about 300-- really odd, and i bought it back up to 900 or so...shut the car off, replug the maf...and seems to be working okay...

hope this helps

jacobmh

I cleaned my TB and my idle went up a bit as well I am going to be cleaning the IACV this weekend or next and I will be resetting the idle

sparky1562

Did you check the high idle cam and see where it is when its cold versus hot?

Can I get anyone to check theirs?

mevjen

Could it be because your car is cold? I have noticed my rpms are higher when the car is cold and then return to the normal range after the engine reaches operating temp.

sparky1562

If you are responding to my post, I am pretty sure it is the high idle cam. The piston on the throttle body is not moving out as the car warms. Then when it does get warm, it is still sitting on the high idle. Can't seem to interest anyone into seeing how far theirs moves.

humaras

sparky--
i am uncertain about the high idle cam. But since there has been a lot of discussion on this and I too have reviewed a lot of documentation online-- I will start from beginning about three years ago and what I have done to this day-- but there still is the occasional unexpected high idle.

It started about 3 years ago in the fall when after driving my maxima, I shift the car into PARK and i noticed the idle jumped to about 1500/1600 RPM. The sympton went away. So it happens more often in colder weather between november and march when after driving a period on the highway (mostly) the idle would be in the 1500 range, and if the car is in Park it is say 900, but you can feel the "pull in the car"-- because of the higher RPM.

I had the throttle body clean, spark plugs changed at that time --about 70K. I messed around with the IAC air screw but did not adjust with unplugging the TPS sensor. But the symptons still existed. Recently my car stalled twice last week so I went through the manuals to see if it was the IAC screw and adjusted that...was okay for a few days...but after driving (car warm), occasionally the engine would rush to the 1500 range but after some more driving the idle would be normal.

What is annoying is that this is unpredicatable the rise in the idle. Not the knock sensor...car doesn't knock. Only other is replacing the MAF...dealer and mechanics have not been able to accurately diagnose this.

So-- this is where I am...any thoughts?

sparky1562

I backed the high idle cam off so that it basically does not function. I think it is froze up, but so far I have not had trouble with cold starts. It would keep the idle at 1500-1600. That was fairly obvious what was going on.

I still seems to exhibit a higher idle from time to time, did it last night when we came home from dinner. Idle was around 1100 when I put it in park. Doesn't do it all the time, just some times.

I did adjust the idle per the other posts on the site. Checked several of the sensors per the Haynes manual, all are okay. No vacuum leaks that I can find. Kind of stumped. This is from before I cleaned the TB.

Attachment 322

humaras

yes, i agree with you that i too have checked for vaccuum leaks and also other things and i have not found any.

the odd ball sporadic high idle comes and goes as well and when i put it in park sometimes it oculd be anywhere from 1100 to 1400...but interestingly enough after a bit of the high idle it would come back down...

One thought I had on this is --at the high idle, is the mixture of fuel to air burning too "rich"? if that is the case it could be the knock sensor *but no code so far* or MAF sensor? or anything else?

sparky1562

I checked my high idle cam again, and it was still touching slightly. I made sure this time it can't. You might want to check that (see the PDF I attached).

I took the thermal device off the TB, freed up the little piston, but it still does not move out when it gets hot.

Does anybody have a replacement for the thermal element on the TB? Of course dealer told me it only comes with a throttle body!

KRRZ350

iTrader: (29)

PM 99blackmaxms for a TB

oldngivout

iTrader: (8)

I have replaced them on other Nissan vehicles before. Don't know if your dealer is just being lazy, but they are available separate from the TB.

oldngivout

iTrader: (8)

http://www.courtesyparts.com/betasit...1800_1801.html

sparky1562

YIKES! $ 118!!!!!
If she starts fine in cold weather I think I will do without!

Thanks guys!

oldngivout

iTrader: (8)

Oh, when it's not working, it will always start, it just won't idle down.

Annoying with a manual trans, downright aggravating with an auto.

ZRob

My car stalls every few days...idles high in park as well, that I don't mind (as much), but it would be nice if it would quit stalling. Have cleaned TB and IACV have a new TPS on the way and picking up coolant temp sensor Thursday. Will clean EGR pipe and install new parts on Friday...hoping fixes stall issues...stalls occasionally when coming to a stop no rough idling just cuts out.

I am new to the world of Maxima ownership but have already gotten some great info from this forum....had a Z 5yrs back. Its good to be back in the Nissan world. The Max is like my 4dr Z car. Now the kids can enjoy the ride too...until it stalls....

shilov

My idle goes high to around 900 every time I clean the TB (I did it twice so far). I need to reset ECU and go through the procedure of setting the idle. It gets to normal (~650) afterwords. I think ECU needs recalibration every time you change the condition of your intake.

sparky1562

I just took it out of the picture. Always on the low idle cam. If it was $ 20-30 I would replace it, but at $ 118 I will just leave it as is. A friend has a 98 Max. I think I will just swap mine for his when he's not looking.

mactaite

can anyone tell me what the black switch to the right on the throttle body is. and maybe an estimate on how much it cost.

The Wizard

iTrader: (43)

^^^ That's your TPS (throttle position sensor) Cost is around $85 new.

mactaite

thanks also
i have a problem can anyone help me out. i have a 97 max with 190k+ miles. i have problems getting the car to start whenever the car is cold or has been sitting for atleast 4 or 5 hours. the engine turns but i have to turn the key about 4 or 5 times then it starts. i have cleaned the iacv and the tb. i checked the sensors and fuel injectors. i havent thrown any codes. battery is new. i have a small oil leak but nothing major. Are there any suggestions????

mactaite

also when i accelerate over 80 my car starts to vibrate a lil