Dave Holmes

I have a '97 Maxima with 133,000 miles on it. I have an intermittent high idle when I come to a stop and/or put it in park. This happens after it is fully warmed up. There aren't any drivability problems. The idle is normally about 700 in drive, and about 800 in park (when warm). But sometimes the idle in drive goes to 1000-1100, and in park it's about 1200 (just like it does when the car is cold). But this is even after it has been driven 30+ miles. And it doesn't do it all the time.

Here's the things I've checked: pulled codes (none stored, got 0505 several different times), maintenance is current (new fuel filter & PCV, clean air filter, oil good, plugs good), checked O2 sensors through ECU diagnostics (both upstream checked out according to FSM). Checked following with ohmmeter and tested good according to FSM specs: IACV, Cam Posit Sensor, TPS, upstream O2 sensors. The Engine Coolant Temp sensor tested bad (the one for the ECU), and was replaced. This didn't cure it (although it seemed logical to me that it could have been the problem. ECU would think engine was cold, and bump up the idle. But it wasn't it. The new one tested good). All grounds are good and clean, battery fully charged, alternator putting out 14.2+ volts, tranny shifting correctly, and the stereo works OK (although I get a CD error every once in awhile on cold mornings). My clock also doesn't work all the time.....

I'm beginning to think it is a mechanical problem not related to any electrical sensors. I would think that is a possibility because if it was a sensor or electrical device, wouldn't it store a code? I've checked for obvious vacuum leaks, but all hoses appear/feel in good shape (couldn't a small amount of unmetered air bump up the idle? And things expand when hot, so that could explain the intermittent aspect when warmed up). I'll be checking for vacuum leaks more in depth tomorrow. The TB has been cleaned in the past 10,000 miles or so. I've also adjusted the idle (black plastic screw on IACV) according to instructions in the FSM. Interestingly, when I re-adjusted it today while it was idling high (1200 in park), the idle wouldn't go down but maybe 100 rpm even with the black screw all the way in. The normal position for mine has been 1 3/4 turns out.

Anyone have any ideas? Has anyone encountered this before? I've been scratching my head on this one for weeks now. I've been thinking of things I haven't checked, like coil packs, injectors, fuel pressure regulator, and crank sensors. I would think coil packs would set a cylinder mis-fire code, FPR would have drivability problems, crank sensors would set codes and drivability issues. I'm not sure about injectors. FSM says resistance should be 10-14 ohms between terminals, so I'll check front 3 tomorrow (back 3 may wait because upper intake manifold has to be removed to get to them). Hopefully someone can chime in with an idea before I get that far.

Thanks in advance,
Dave

pmohr

iTrader: (26)

When you adjusted the IACV, you unplugged the TPS first?

I know KRRZ350 has had experience with a car that would have idling issues (including idling high when it wasn't supposed to) that turned out to be a bad ECU.

As far as the clock, probably just a cold joint. I've got a few for sale, see my sig

Dave Holmes

I had the TPS unplugged when adjusting the idle.
The thing that's stumping me is there are no other symptoms. No drivability problems, no "surging" idle, no loss of power or even gas mileage. I'll do a search for KRRZ350's experience with his idle. Hopefully it's not the ECU.

My clock started going out several years ago. No big deal for me, cause I wear a watch. I think it's funny cause my wife doesn't. Helps keep her out of my car...

Thanks for the help.

Dave

jam36a

Have you cleaned the throttle body?

Have you checked your O2 sensors?

How about the fuel pump?

oldngivout

iTrader: (8)

Check the throttle assembly to make certain it is fully closed during idle. Do this after the car is thoroughly warmed up and running. The area circled in red is the key. The clearance between the throttle stop and the adjusting screw should be zero. If is is not, then the cold idle plunger is not fully releasing, and the throttle plate is open too far. This condition will prevent the idle from falling to the normal range after warm-up.

IlyaK

iTrader: (47)

How did you have the TPS unplugged to adjust the idle?

Doesn't the car stall if the TPS isn't plugged in? I know I unplugged mine, started the car, and within seconds it stalled.

njmaxseltd

iTrader: (19)

The cold idle plunger could be hanging up or the throttle body coolant passage could be clogged causing the TB to get cool and activating the cold idle plunger.

Also do a proper idle speed adjustment. Set the default throttle body stop first, then adjust the IACV. Follow these steps:

Warm the engine up completely, drive it around for 10 min.
Turn engine off, disconnect TPS
Start the engine, no lights or acc. on at all, no load on the engine.
Adjust the default throttle body stop screw to optain ~550 - 600 RPM's
Turn off the engine, reconnect the TPS
Start the engine, verify correct idle speed of 650 - 700, if it's incorrect adjust IACV to obtain the correct idle speed.

Hope that helps you out.

pmohr

iTrader: (26)

No, the car should run fine without the TPS.

Where are you getting the 'adjusting the set screw' from? I've seen you post that a few times, but the FSM doesn't say to do it at all. In fact from what I've heard it's more of a bad thing to mess with that. Also, according to the FSM the TPS has to be unplugged to adjust the IACV.

Dave Holmes

jam36a-TB is clean (less than 5000 miles or so). O2 sensors passed ECU's diagnostics, and an ohmmeter. Haven't checked the fuel pump. I think it would give general drivability problems. But I'll check it anyways.

oldngivout-Interesting, and a good idea. IIRC, I've noticed in the past that there has always been a little clearance there. I don't think I've ever seen it touch, and have thought previously that was weird (it really struck me as odd, because it is an idle stop screw that wasn't doing its intended job, and I know Nissan didn't add extra nice things to my car that serve no purpose) . But since I didn't have any problems, I didn't dig deeper in to it. I'll check clearance hot and cold, and look up the specs in the FSM. Do you have any more tips about it? Anything specifically to look for?

Ilyak-The TPS needs unplugged to accurately set idle. Warm up the car, turn it off, unplug TPS (in oldngivout's excellent photo, it's the brownish connector partially visible in the upper right corner), start car back up, adjust idle via black plastic idle adjustment screw on IACV, turn off car, plug TPS back in. You'll set a DTC in the ECU, so you'll need to clear it after plugging the TPS back in. When you did it and had your car stall, did you unplug the IACV by mistake? Common problem.

Thanks to everyone for responses so far. Keep the ideas coming. It's a nice day out today (high should be 72*F), and I have the time to check things out. Supposed to rain Fri and Sat, so hopefully I can make progress today.

Dave

IlyaK

iTrader: (47)

Ilyak-The TPS needs unplugged to accurately set idle. Warm up the car, turn it off, unplug TPS (in oldngivout's excellent photo, it's the brownish connector partially visible in the upper right corner), start car back up, adjust idle via black plastic idle adjustment screw on IACV, turn off car, plug TPS back in. You'll set a DTC in the ECU, so you'll need to clear it after plugging the TPS back in. When you did it and had your car stall, did you unplug the IACV by mistake? Common problem.

-------------------------

No sir. I'm not a newb lol. I know just about where everything is in the engine bay. I've ripped apart the manifolds on these motors more than once.

I'll have to give it another try. I've always just done it with the car running and the screw on top of the IACV. Never touched the TPS after that one time.

Dave Holmes

njmaxseltd-Our posts must have crossed in the mail. I've looked at the idle speed stop screw in the past, but haven't adjusted it because it isn't mentioned in the FSM. The Haynes manual actually says not to adjust it, as it is factory set. So I've always left mine alone. Mine even had the factory inspection paint on it like oldngivout's pic, but it has since mostly come off during TB cleanings. I'm old enough to have grown up adjusting carbs and have been tempted to adjust the idle stop screw, but have had to learn to trust these new fangled computer controlled thingys. Maybe my trust has been mis-given, and I may need to adjust it. I'll go through the FSM procedure first to double check things.

You've got a very good point about the cold idle plunger. Any tips on checking it? I think I'm going to pull my TB, clean out the coolant passages (which should be clean, from what I can see from the rest of the cooling system), and go from there. Can the cold idle plunger be removed to clean it? If it's bad, can it be replaced without replacing the entire TB? Right now, with engine cold, I've got 1.346 mm gap at the idle stop screw. I'm going to run in town to warm up the car (and get a TB gasket so I don't have to make my own), and I'll check the gap again when the engine is hot. I'll be back within the hour.

Thanks again everyone.

Dave

Dave Holmes

Just returned from a little drive. Car fully warmed up. The gap at my idle stop screw is at .559 mm. Seems to me it should be touching. Also noticed there is an adjustment screw at the cold idle plunger. Neither of these stop screws have been adjusted on my car before. I'm going to pull the TB, clean the coolant passages, and inspect the cold idle plunger the best I can. I'll check to see if it is removable and clean it up as well.

Dave

IlyaK

iTrader: (47)

I just got de-00VI'd. My coolant passages aren't connected. I don't have any coolant leaking anywhere...so I dunno how the guy who did my swap managed that (I musta missed that part of the install).

Although I don't have any issues with my car (I was just reading the thread and noticed the part about the TPS)...is this necessary or will I be find long term without it?

oldngivout

iTrader: (8)

The cold idle plunger is replaceable. It's listed on Courtesy's site as a thermo element kit #16391U.

http://www.courtesyparts.com/maxima-...1800_1801.html

Dave Holmes

Ilyak-Interesting. I've read other forums where people mod their TB's by by-passing the TB coolant lines. Easy enough to do (just get a longer hose to span between where the coolant hoses normally connect on the engine). The consensus though is that it doesn't do anything constructive. Nissan put the coolant passages in the TB for a reason. Operation of the cold idle plunger would be one. With the coolant hoses by-passed, there might be cold idle issues. A lot of shops would probably adjust the idle speed to compensate for this. But it wouldn't be the optimum configuration.

I've got my TB off and sitting on my kitchen table. Took a bunch of pics because that's just the way I am. Interesting that there are 2 marks on the fast idle cam, and a "corresponding" mark on the throttle lever (the one controlled by the throttle cable). I assume that these are used for adjustment of the cold idle plunger setting. Wish I knew how to post pics on here (and I've been here since Oct '01 or so). I know it has something to do with using photobucket (I have an account) and linking to it from here. I'll upload them to photobucket and try linking them here in a little bit.

Dave

IlyaK

iTrader: (47)

The link you will need to post begins with http:// and ends in .jpg (or any other image extension).

So how do I go revert the bypass? Anyone know?

Dave Holmes

Here's a pic of the idle stop screw gap:



Here's the fast idle cam marks. Notice mine doesn't line up. I don't know if that is the problem. Adjustment has to be made with it on the vehicle, at a certain coolant temp (this is where people with the TB coolant by-pass mod may run in to problems):


Here's a pic of the cold idle plunger adjustment screw. It is possible with 133,000 miles that my screw has "worn" down a bit, causing it to become out of adjustment. I'll see in a little bit if adjusting it cures my problem.


Dave

Dave Holmes

I think I got the pics thing down. They show up on my end.

To undo the by-pass mod, you'll need to re-connect the coolant hoses to their appropriate inlets. You'll see the inlets on the bottom of the TB. There will probably be a 3/8" hose going near them that can be traced back to a coolant line (if it was by-passed by using a longer hose to connect the coolant pipes. If the put plugs over them, you'll need to find them.). This hose connects to the coolant inlets on the TB.

Dave

IlyaK

iTrader: (47)

Pics work.

This is becoming a good thread. Let's keep it going.

Dave Holmes

oldngivout-Thanks for the link to the cold idle plunger. Nice exploded view diagram, too. Makes me wonder if the cold idle plunger is immersed in the coolant, or if completely seperated from it. I don't see an O-ring or anything else to seal it, so maybe the coolant is sealed from it. Wish I had photos of it actually taken apart cause I may do it tonight (if I do, I'll take pics).
I've attempted to adjust mine according to the FSM. It's a kind of a convoluted procedure using an ohmmeter to check resistance of the engine coolant sensor (in essence to determine actual temp) and adjusting the cold idle plunger stop screw to line up the mark on the throttle cable lever with the short line on the fast idle cam when the engine is warmed up. Mine doesn't come close. The throttle cable lever line only gets to halfway between the two marks on the fast idle cam before I run out of screw (it is being turned in to make the adjustment). Seems if the plunger would come out more, I could get it adjusted. Makes me wonder if it can be cleaned up or something (Courtesy Nissan's price of $120.71 is a little steep if it could be fixed). I may take the TB back off and take it all apart tonight, unless anyone knows anything else about it.

Ilyak-Here's a pic (hopefully sized a little smaller than my above) to help you out with the TB coolant bypass thing. I circled the TB end of the coolant lines in red (they have a plug in them to prevent coolant loss), their origins are circled in green, and the blue arrow is a vacuum line that goes to the bottom of the TB (I think it's for automatic tranny's and 5 spds have a cap over the TB vacuum port). In the TB by-pass mod, the two coolant lines are connected together or replaced totally with one longer hose. Or the points of origin are plugged.


Thanks again everyone.

Dave

IlyaK

iTrader: (47)

Thanks Dave. Do you mind PM'ing me the link to the full-res shot? Thanks.

pmohr

iTrader: (26)

I've taken it apart before, you can strip down most everything there. Just be careful with the nut on the shaft that holds the linkage, I tore up the shaft when I removed mine; still have the old TB around here somewhere, with no FIC equipment at all.

FWIW I've had my TB coolant bypassed since near when I got the car, never had any starting issues because of it. If you remove those lines, remove the lines going to the EGR port as well, makes pulling the UIM much easier (can do it in ~5 minutes on my car).

The backside of the FIC thermovalve is immersed in coolant, I can see what appears to be an o-ring groove in the cylinder (and see the path of the coolant lines). On my spare TB (which was an auto) the bottom vacuum port is capped off as well.

IlyaK

iTrader: (47)

So you're saying having coolant or not isn't really a big deal? I shouldn't worry about it? My car drives/idles fine, although I might unplug the TPS and adjust the IACV a little bit.

pmohr

iTrader: (26)

I have noticed absolutely zero difference with or without the FIC functional.

sparky1562

I had the same problem last fall. High idle when warm. It was the thermal element in my case. I put a spacer between it and the high idle cam to solve the problem. When it gets down in the low 20's here, I have to hold the throttle for 30 seconds or so to keep it running after starting it.

Pmohr, you told me at that time that you bypassed yours and don't have any problems, but that is what my problem was.

Maxima Joe sells used TB for $10 and you could try the element in one of those. The new one is like $118. I decided to just live with the hard cold start for now.

Dave Holmes

Good info everyone.
pmohr- I've got my thermo-element retaining screw out. But the element itself appears stuck in its bore. I really don't feel like forcing it. The piston itself came right out of the element. No type of retainer or anything. Mine felt like it had a little resistance in a spot. When removed, it had what looked like a black dried up grease on it. Looking into the hole where the piston goes, it appears the coolant doesn't actually touch the piston, but the back end of the "casing" may be immersed in it. There was more dried up black grease in it. I'm probably going to put some white lithium grease on it and put it back together. There is an o-ring in the bore that the shiny piston goes in.
The bottom vacuum port on mine has a small vacuum hose that goes down somewhere around the tranny. I didn't trace it to its endpoint, though. The Courtesy Nissan diagram linked above shows a cap where I have a hose. Weird.

Here's what I have so far:

and



You can see the o-ring in the thermo element bore, and the piston that goes in it. I didn't have any problem with the nut holding the fast idle cam on, but the screw holding the retainer for the thermo element was a pain. I almost stripped it out. The spring for the fast idle cam is pretty strong. Should be fun getting it back on.

Dave

JtzMax

iTrader: (5)

This seems to be a very common issue with the A32. I have issues where when I drive, even at hiway speeds, and I come to a stop (5spd - or when I go to 'N'), my idle will stay at ~1300 or so .... stays that way for 10 seconds or so, then finally drops to normal range (~700 rpm). I also have hard cold starts (intermittent - of course!) but I'm not sure it's due to the TB at all.

New fule pump, cleaned TB / IACV (removed both and cleaned), TPS checks ok. Also, anyone else have any issues with thier cars 'eating' oxy sensors? I've replaced my left bank (pre cat) O2 sensor now 3 times (within 1 1/2 years). No exahust leaks that I can see (had a small one, but got it fixed a while ago) nor do I hear or smell any. I dunno ... they blow before the end of warranty anyway, so it's just a matter of ... here, have another one.

pmohr

iTrader: (26)

The piston itself is pushed by the 'casing' (thermovalve) which touches coolant. The valve can be pulled straight out of the TB, it'll likely just be stuck in there as it's never been removed before.

Dave Holmes

Who is Maxima Joe? That would be convenient to just have a spare and parts.

Kevlo911

iTrader: (36)

Great info, I too have this problem and this might be the solution

I do not have my coolant hooked up either I am hoping the idle is back to normal when I fix this.

IlyaK

iTrader: (47)

Well me and PMohr aren't running coolant and it doesn't seem to affect us.

Maxima_Joe is formerly known as fanaticrockford. He's the guy who basically parts out 4th gens for a living.

pmohr

iTrader: (26)

http://forums.maxima.org/private.php?do=newpm&u=5900

JtzMax

iTrader: (5)

That's one way of putting it, yes. lol

I have my coolant lines still hooked up, maybe I should bypass the TB? Also, I never noticed it before, but I did today when I popped the hood - I have a repetitive click at idle, seems to be coming from my TPS. Like I said, I never noticed it before but I'm certain it's the TPS. What would make it start 'clicking' and would that cause the problem of the idle not returning to 'normal' after disengaging gear? When the car sits and idles, I pop the throttle and it settles back to ~750 rpm. Only seems to 'stick' after being in gear.

pmohr

iTrader: (26)

The TPS can't click, you're hearing the IACV. It's possible that it's trying to step down but one of the plungers is sticking, and giving it throttle (which closes the IACV AFAIK) is able to 'reset' it for lack of a better term.

You should pull the IACV, strip it all down and give it a good cleaning.

JtzMax

iTrader: (5)

I've just done that, but I had this issue prior (not the clicking) to doing this as well. The IACV gasket wasn't replaced (I just used sillicone gasket instead) but I don't think that it's 'sucking' air. I will pull it back off and re-clean it. Maybe I jacked something up when I did it before. There are 2 plungers / sensors on there - are they both replaceable, would that be needed? Also, would it hurt to lube the plungers with something?

pmohr

iTrader: (26)

As far as I can see through FAST, you can't get individual parts for the IACV.

Those two are just for the PS and AC, you can unplug those and see if the clicking goes away. As far as lubrication, not sure. I haven't torn apart an IACV in a long time.

sparky1562

Have you ever marked the piston to see if it moves out with just the heat of the TB? With the engine cold, is the throttle on the high idle cam?

Seems odd to me. I marked mine and it never moves. Pulled it out and tested it in hot water, no movement. I just put it back and put a space on the end of the piston to keep it off the high idle cam.

Dave Holmes

An update. Got everything back together last night after cleaning/greasing the piston of the thermo-element. Ran the car, and adjusted the idle via the thermo element/fast idle cam and then the IACV idle screw. Got it dialed in at 700 when warm, in drive. Test drove it today, and the idle seems pretty good. At initial start (cold), it is at 1500 (injectors are in "batch" firing mode for a second or 2), then immediately drops to 1200. A very short while later, it drops to 900. Idle in drive is 700. After driving 15 miles or so, including in the city, the idle stays at 700 in drive. With the AC on (it was in the 70's here), the idle naturally bumps up to about 750. In park, the idle is at 900. This still kinda seems a little high, but I can probably live with it.

Sparky- Interesting idea. I'll have to run some tests on mine with it all hooked up to see if it is beneficial. I can use my IR thermometer to get some temp readings of the TB and the thermo element area to see if there is any heating/cooling going on. I did notice so far that the thermo element area of my throttle body stays relatively cool to the touch (not burning hot). I think the amount of air going through the throttle body probably prevents it from getting as hot as say a coolant hose. I'll check temps of the coolant hose going in and coming out to test that cooling theory.

Dave Holmes

Just a follow up. I tested stuff again today, and took pics to show the movement of the fast idle cam.

This pic shows the marks on the fast idle cam with the temp of the thermo element area on the TB at 44.4 degrees (prior to any start of the day). You can see the laser spot from the IR thermometer, and notice the mark on the throttle lever are to the left of the "long" mark on the fast idle cam.



Close up of the fast idle cam at the same temp (44 degrees or so). Marks are more visible.



This shows temp at 89.8. The engine was idling for a few minutes, and the interior temp gauge was reading just shy of normal operating temp (halfway or so). The fast idle cam has barely started moving.



This is after the few minutes of idling, and a good 10 miles trip. Car is at normal operating temp, even though IR thermometer shows 99.8 degrees (these are all in Farenheit). Notice where laser dot is (little nub on TB). IR thermometer isn't broken, my radiator hoses were showing in the 170's, and my fans were cycling on and off. The TB doesn't get as hot as the engine components around it. I can only guess it is from the volume of air going through it. But apparently it gets hot enough to operate the thermo element. The fast idle cam marks have definitely moved to the left (thermo element piston extended).



Here's a better shot of the marks at the same temp.


These show that the fast idle cam does indeed move on my car. But if you read the FSM's directions for adjusting it, there is no way it can be done to my car. There is no way for me to adjust the fast idle cam screw in enough to get the throttle lever mark on the right mark of the fast idle cam. I simply run out of screw to turn in on the fast idle cam. If the screw was longer, possibly. Maybe the tip of mine that rides on the thermo element piston has worn down some. There's a pic of it earlier in this thread. I can't tell if it is supposed to be that "flat" on the end, or slightly more rounded or pointed. Can someone check theirs?

In one of my posts in this thread, I wrote I noticed my throttle lever never touches the idle stop screw (the one on the top). It does now when warmed up. To my knowledge, my idle stop screw has never been adjusted. When cold, there is still about a 1 mm gap (I should measure it tomorrow when it is stone cold).

For those with the TB coolant bypass, I don't know how or if any of this affects you. If you don't have any cold idle issues, I'd probably leave stuff alone. But if you do have idle issues, this may be something to look at. For people with idle issues that still have the TB coolant lines hooked up, I would check the thermo element. My piston was "sticking". After cleaning off dried grease, and regreasing, it slides easier now. And my fast idle cam works. More importantly, my cold idle is acting properly.

Hope this helps.

Dave

JonBlz

iTrader: (11)

im gonna try this