nicks79

iTrader: (4)

So i just installed new IACV, hoping it would fix my weird problem, but no luck. I have 00 5sp max, with 135k miles, new coils, new MAF. I cleaned TB around the butterfly. New fuel filter, new plugs and this still happanes.

When i let rpms drop, say while putting in neutral, they drop to about 300 and get back up to around 600. They don't drop to exact number all the time, sometimes to little lower, other times to about 400rpm. Now when theh car has been driven for a while, like i stopped on the highway yesterday to get gas, when I started it up, it stalled.

ANY ideas? This is so frustrating...

Also, ddoes IACV opens air passage when at closed throtle or it simply measures how much air bypasses closed throttle? I assume it opens the passage, thats why its called valve..

Thanks for all your help

nicks79

iTrader: (4)

I just found this, could it be the problem that Crankshaft sensor is gone?

"""""""""""""""This system automatically controls engine idle speed to a specified
level. Idle speed is controlled through fine adjustment of the
amount of air which by-passes the throttle valve via IACV-AAC
valve. The IACV-AAC valve changes the opening of the air by-pass
passage to control the amount of auxiliary air. This valve is actuated
by a step motor built into the valve, which moves the valve in
the axial direction in steps corresponding to the ECM output signals.
One step of IACV-AAC valve movement causes the respective
opening of the air by-pass passage. (i.e. when the step
advances, the opening is enlarged.) The opening of the valve is
varied to allow for optimum control of the engine idling speed. The
crankshaft position sensor (POS) detects the actual engine speed
and sends a signal to the ECM. The ECM then controls the step
position of the IACV-AAC valve so that engine speed coincides with
the target value memorized in ECM. The target engine speed is the
lowest speed at which the engine can operate steadily. The optimum
value stored in the ECM is determined by takig into consideration
various engine conditions, such as during warm up,
deceleration, and engine load (air conditioner, power steering and
cooling fan operation)."""""""""""""""""""""

MaximaEvolution

iTrader: (2)

check for vaccum leaks ??

nicks79

iTrader: (4)

How? I checked all the hoses that go mid-pipe, which is stock, they all tight, and seem OK, no cracks or anything. I mean is there a method for doing it? Light a lighter and see it flame gets sucked in while accelerating?

Also is Crank pos sensor common to go on our cars?

P. Samson

Did you accomplish the Idle Air Volume Learning procedure. It is a must do.

nicks79

iTrader: (4)

No I didn't do it, I thought it was only for 02-03 models.. Also, if I didn't do it, wouldn't idle be set at some incorrect level? In my case drops to below 400 and gets back up to normal..

monty31

iTrader: (1)

I just installed a new IACV two days ago and am also havin major issues, although not the same as yours. My idle is at 1500 when I start the engine, ~1000 in drive. Then once the motor warms up, the RPM revs a little bit in park. Also, my CEL came on again. In my case it's probably a shorted ECU which I've been reading about in numerous other threads. The idle relearn proceedure did nothing for me.

Are you still getting a CEL?

P. Samson

It's a Gen. 5 requirement as well as a Gen. 5.5. If your idle droops to 400 rpm then it's incorrect. With the engine WARMED UP the correct manual tranny idle is 625+/-50; the Auto is 700+/-50 in Park or Neutral. The idle should be stable without "hunting". You should probably reset the TPS idle position memory as well. Did you disturb the TPS during your work on the car?

nicks79

iTrader: (4)

I had battery disconnected for over an hour. It should loose all its settings. In 2000, butterfly is mechanic, can you really mess it up? I thought that only happens in drive-by-wire cars, like 02-03...

P. Samson

No, disconnecting the battery does not affect the requirement for the Idle Air Volume Learning for the work that you've performed.

nicks79

iTrader: (4)

OK, i'll try to do lear IDle air procedure..

P. Samson

This is the Idle Air Volume Learn (Without CONSULT-II)

1. Turn ignition switch “ON” and wait at least 1 second.
2. Turn ignition switch “OFF” and wait at least 10 seconds.
3. Start engine and warm it up to normal operating temperature.
4. Check that all items listed under the topic “PRE-CONDITIONING”
(previously mentioned) are in good order.
5. Turn ignition switch “OFF” and wait at least 10 seconds.
6. Start the engine and let it idle for at least 30 seconds.
7. Disconnect throttle position sensor harness connector (brown),
then reconnect it within 5 seconds.
8. Wait 20 seconds.
9. Make sure that idle speed is within specifications. If not, the
result will be incomplete. In this case, find the cause of the
problem by referring to the NOTE below.
10. Rev up the engine two or three times. Make sure that idle
speed and ignition timing are within specifications.
ITEM SPECIFICATION
Idle speed M/T: 625±50 rpm
A/T: 700±50 rpm (in “P” or “N” position)
Ignition timing M/T: 15°±5° BTDC
A/T: 15°±5° BTDC (in “P” or “N” position)
NOTE:
If idle air volume learning cannot be performed successfully,
proceed as follows:
1) Check that throttle valve is fully closed.
2) Check PCV valve operation.
3) Check that downstream of throttle valve is free from air
leakage.
4) Adjust closed throttle position switch and reset memory.
(Refer to Basic Inspection, EC-111.)
5) When the above three items check out OK, engine component
parts and their installation condition are questionable.
Check and eliminate the cause of the problem.
It is useful to perform “TROUBLE DIAGNOSIS — SPECIFICATION
VALUE”, EC-143.
6) If any of the following conditions occur after the engine
has started, eliminate the cause of the problem and perform
“Idle air volume learning” all over again:
I Engine stalls.
I Erroneous idle.
I Blown fuses related to the IACV-AAC valve system.
Before you changed out the IACV what was your intitial problem anyway?

monty31

iTrader: (1)

Yep ^ Some things to make sure you also do before the test include making sure your battery is giving you over 12.7 volts at idle, turn off all lights, steering wheel straight, codes cleared, cooling fan off...might have missed some stuff. Hope it works for you, didn't do anything for me.

nicks79

iTrader: (4)

So I tried this learning procedure. No luck. Everyhing seems to work OK, the only thing I didn't try was measuring the battery, but its fairly new. Still Idle is wacky, drops down before it gets to the right point.

SSzretter

I had a similar problem, and what fixed my idle was
1. clean the IACV
2. replace pcv valve
3. use 'super' gas

have not had an issue since

nicks79

iTrader: (4)

I have all that, NEW IACV, newer pcv and always use premium gas..

monty31

iTrader: (1)

Probably going to have to replave your ECU.

nicks79

iTrader: (4)

why would that be a problem... Evrything else works fine....

SSzretter

I wonder if it could be something to do with the idle adjustment screws? I know on mine after cleaning the iacv, my idle was off, and I had to turn a big plastic screw on the top to adjust it. Plus I have read that there is another screw to adjust too. Possibly there is a procedure for resetting these screws to some point, then adjusting them to proper idle?

nicks79

iTrader: (4)

the thing is that when you don't anything, meaning car is adling, its set to normal speed. But, when rpms are dropping down, say when shifting, it drops to below normal (around 300-400) and comes back up.
Also when the car is worm, you want to start it, sometimes it'll stall so you have to give it gas, but this doesn't happen every single time. Its intermittent. IT DRIVES ME NUTS>>>>

monty31

iTrader: (1)

All my stuff worked fine too except for the idle.

dmaljunk

did you get this resolved? I have a 2K Auto and have a similar ptoblem, exactly what you said - when car is warm and you start it, sometimes it rattles for 5-10 seconds but rpms seem normal though, then it evens out and rattle goes away. I had IACV and ECU replaced at the same time, dealer did it and probably ran the idle learning. Later on, I had my throttle body copletely removed and cleaned, may be I need to do the idle air learning again. This issue drives me nuts too, did anyone have any luck fixing it?

nicks79

iTrader: (4)

No, still haven't fixed it. I am planning on getting one of those software to hook-up to ODB and see whats going on. Now though when I start it from cold, rpms drop to 1000 and then surge up to aout 1350 like it should...

I tried RPM Idle learn, didn't work. Will try again..

aongch

Will an IAF issue kill my idle at off-throttle, i.e. slowing down, shifting for a corner? This is my problem, but intermittent. Idle drops way low then engine dies, but no problem restarting. Idle is steady. I do still need to see if the TB, MAF, filter are clean, but is this a known symptom?

super6

iTrader: (5)

how new is your maf? do you have an intake? if the tb has been cleaned, you can also try to spray TB/MANIFOLD cleaner in there. there may be two bloblems... unlikely but possible is that the harness from the iacv is bad. another thing is that in rare cases when replacing the iacv you may need to replace your ECU. i didnt have to but ive heard others say its nessisary sometimes. it is normal for rpms to go to likr 450 or 500 before going back to idle, but if ur dipping to like 300 is is too low. make sure there are no vacume leaks and try to do the idle re learn.

if you did absolutly everything and other than that sypmtom your car runs fine, maybe just manually adjust your idle 100-150rpms higher.