matrix11229

I just cleaned my IACV (the car has 189k and I think it was never cleaned).
I used throttle body cleaner and I cleaned both IACV and in IACV hole inside the intake.
First, the engine stalled; on the 2nd start it almost stalled but then worked normally.
BEFORE

IACV

Inside the intake


AFTER

IACV

Inside the intake


Questions:

#1. There is a black dirt inside the intake (see the last pic) and it doesn't come off (I used a long bolt to clean inside there). Do I have to clean it more ? and does it affect performance if I will leave it like this ?

#2. I adjusted the idle speed by using the plastic screw on IACV. I set it to 700 and the screw is tightened almost all the way inside. When I shift to D the rpm drops to 600. 600 at D is a bit low but if I loosen the plastic screw to set it to 650, the Idle at P will jump to 750~800.

Some people adjust idle by using the stop screw on throttle body, but then I will have to disconnect the Throttle Position sensor and probably it will trigger the CEL and I will have to reset the ecu. I don't wanna recet the ecu anymore after I finally got rid of the Evap codes.

Is this enough to adjust the plastic screw only as I did, or I have to use the stop screw on throttle body and will it turn on the cel if I disconnect the TPS?

Thanks

eat1000

according to my understand, that plastic one is the only place to adjust idle

Cdg2125

iTrader: (7)

Well discounting the ECU will reset anyway and get rid of the codes. If you fixed them then you shouldnt worry anyway. If you took off the IACV to clean it why wouldnt you clean everything you can? 600 in D isnt that bad. Best is considered 640 or something close to that. Maybe it was 680....now I cant remember.

shadyonedeath

iTrader: (10)

Your fine at 600. Dont worry about it so much.

As for the dirt inside your intake, thats probably from ALL the miles or a bad egr system. Dont remove the intake manifold unless you have a new gasket for it, for it will cause a vacuum leak.

Your good where you at right now.

matrix11229

I was trying to clean as much as I could inside the intake hole, but I couldn't see what I was doing. I was able to see what's going on inside there by taking pics with my camera. I think the black dirt cloggs some kind of egr valve there.
Before the cleaning it was idling at 850 in P and 650 in D. Also my gas mileage is bad (13mpg-city) and I replaced mostly everything that affects mileage and there is no change in mpg. I guess that a clogged egr doesn't affect gas mileage during short trips in the city ?

shadyonedeath

iTrader: (10)

Yea, that arrow is pointing to the EGR tube. It looks bad.

If you really want to clean your Intake manifold you need to buy a new gasket, remove it(Intake), Hose it down with Throttle body cleaner, and take off and clean that EGR tube behind it. (the one in the arrow). Hose that down with cleaner also, it looks bad, really thick sludge.

Im just warning you IF you do this, be prepared to work for about 3-5 hours removing//cleaning/assembling everything.

Cover the lower intake manifold ports when you remove the Upper-intake manifold, dont get anything in there. Just stuff it with rags until your ready to assemble everything.

Any questions?

matrix11229

I don't wanna mess up with intake manifold removal. I don't have a torque wrench and a garage to do it. I repair everythin on the street. I think I hear some vacuum leaks near the passenger side but it's not that bad.

Is this possible to clean that egr tube without removing the manifold ? I sprayed throttle body cleaner and used a long bolt to remove that black thing there but it feels like it's rock hard and doesn't wanna be removed ...

Your egr tube was clogged too ?

shadyonedeath

iTrader: (10)

I didnt even thoroughly clean my egr tube, and looking back at the hassle the Intake manifold gave me(my fault), i dont want to do anything to it if im not getting any codes.

Mine was dirty also, but only where the opening is. I just used a shop towel to remove everything and sprayed some TB cleaner inside.


You dont really need a torque wrench. I didnt, but then again, i stripped one of the threads on the lower intake manifold(where the upper bolts on) because i didnt know i had to replace the old gasket.

I had a huge vacuum leak and assumed i didnt torque it enough which eventually caused one of my threads to strip. It still tightens up though, so everything is ok.

Just torque it by hand, then use a open socket rachet until its tight(not too tight), and give it one more 1/4 turn.

That should be enough.

The tightening sequence for the 4 bolts is

o-o-o-o
4-1-2-3

nhaven

Yes.

http://forums.maxima.org/showthread.php?t=496494

99grnmaxgxe

iTrader: (11)

Oh boy!

matrix11229

Thanks , I will see if I can do it with the tools that I have.

It looks like it's clogged as bad as my egr tube. But somehow I have no CEL.

Does it affect gas mileage in the city (short trips) ?

Armelius

Think I will do this too. Good post.

Blackwind

iTrader: (9)

NOTE TO ALL!!! when cleaning the IAVC dont mess with the screw. unless your idle changes after you warm the car up.

trust me on this.

drewsblackmax

iTrader: (1)

im guessing that this is from expirience? if so, that sucks

matrix11229

What kind of problems did you have after playing with the screw ?

Before I cleaned IACV, the car idled at 850 in P and 650 in D. According to the manual it should be 650 ~700 in N/P.

Do you prefer to adjust idle using the screw on throttle body ?

Blackwind

iTrader: (9)

yeap i had a bad experience, only cost me Bill to fix it though.

Blackwind

iTrader: (9)

i adjusted my screw according to the specs cause it was still kinda funny and somehow i got codes for the TPS which was not even the problem. i had the screw turned all the way down. so even though the TACH showed almost correct idle it was really at 350!!! when i accelerated the car would shudder BAD and shut off almost everytime i came to a stop. So i had nissan check for codes and adjust the idle. cleared it right up.

shadyonedeath

iTrader: (10)

Thats because your tbs isnt positioned correctly.

Did you remove it? adjust?

Its in the stickies, How-to.

Blackwind

iTrader: (9)

this was over 2 years ago. and yes it was positioned correctly.

nhaven

I think in my case it does effect the gas mileage, because it had a slight ping once in a while, before I cleaned the egr tube.

heynow

iTrader: (1)

dude, don't worry about it. IT's suposed to be around 750rpm in park, if it's lower than that you'll get a feeling that you're sitting in dodge rather than a maxima (treering wheel vibration, not very smooth idle). It's supposed to go down to around 700-650 in D or R. Mine on ther other hand does about 800 in P or N, but it drops down to a very low 500rpm, causing the stering wheel to vibrate.

matrix11229

Did you have any improvement in MPG ? Do you drive in the city or highway ?

matrix11229

I had no problems with the idle. I have the screw almost all the way down, with only the head tip sticking out. It drives fine; It idles at 700 in P and 620~650 in D.
I guess I will get more mpg now because it idled at 850 in P/N and 650 in D before.

Blackwind

iTrader: (9)

then again i do have a 98 maybe that has something to do with it.

matrix11229

Do you have any improvement in mpg after replacing your manifold gasket ?

What was your gas mileage in the city before and after ?

shadyonedeath

iTrader: (10)

Dont know...

I didnt replace it for the purpose of improving anything except fixing the vacuum leak my "stock" gasket made.

And i couldnt really tell you the truth because i had CEL codes for 1005 & 1008 which i fixed shortly after cleaning from the intake manifold to the throttle body.
So yea...

nhaven

Quote:
Originally Posted by nhaven
I think in my case it does effect the gas mileage, because it had a slight ping once in a while, before I cleaned the egr tube.


I guess I spoke too soon. After checking the gas mileage for the last few weeks, it stays about the same before and after the egr tube cleaning.
The resonator outlet pipe(b pipe?) broke off right after the egr tube was cleaned, so the car had a major exhaust leak. I don't know if that makes a difference in the gas mileage. I got it fixed a couple of days ago. I'll keep you posted on the gas mileage for the next few weeks.
On a positive note, the pinging is gone.

petemo95se

iTrader: (1)

One question, did you take off the cap with the 3 screws in your picture? That is where the air comes in. When I took mine off, I had a cone-shape bunch of carbon build-up that came to a point. Did you experience the same thing? That is what helped my idle, by chipping that away, the passage way was clear.

PM

matrix11229

Yes, I took the cap off and it had a cone shaped build-up too. Did you have a wet sludge inside the manifold hole (the hole behind the iacv) ?

matrix11229

How much did you pay for the new B pipe and for the installation ?
My b-pipe is bent under the rear chassis and it's inner diameter is half the original size there.
Please keep us updated on your gas mileage / performance improvement

Thanks

bklynzsleepy

iTrader: (20)

where's the screw on the iacv?

petemo95se

iTrader: (1)

You know, I don't recall seeing any. I'll have to take it off again this weekemd and take a look. If I have some, I'll send some for your stocking

Dexter

DO NOT HACKSAW THAT BOLT OFF!! THATS JUST STUPID, PM ME YOUR EMAIL AND I WILL FORWARD YOU 2da_MizzaX's guide on how to remove the egr tube (and yes you should be able to stick your finger through there so you'll need to clean it all out) that guide helped me out alot and now my car runs a helluva lot better.

Wassup2114

iTrader: (2)

Dexter, please send me that guide. wassup2114@adelphia.net

And in response to your sig, yes, because the speed of light is not affected by its inertial frame. :P

matrix11229

It's on the top of IACV. Look on the attached pics(before the cleaning).

matrix11229

I just sent you a PM . Thanks

FishyMan

Can you forward or PM me that guide too?

gatsugansu

iTrader: (3)

Man that looks bad. My car has 199k and never been cleaned there. I am seriously thinking about cleaning them tomorrow.

matrix11229

I accidently deleted that pm... sorry. The thing is I just got an egr code which means that I have to clean the tube. I reset the cel and it didn't come back yet but I know I have to clean the tube.