MAF, TB, IACV, EGR Cleaning for Dummies on 4thgen Nissan Maxima

Member Credit: 96i30azn

I cleaned my MAF, TB, IACV, and EGR guide tube last week after some extensive research here on the org. I felt like none of the threads included directions for a total newb to do everything. Doing everything at the same time makes sense b/c if you’re gonna get to the EGR, might as well attack everything else while you’re at it so here it is. My car is a 1999 Infiniti i30t, your car might vary slightly in terms of hoses, tubes, and plugs.

1st off, what you’re gonna need:

Tools:
– 3/4 racket
– 8, 10 socket wrenches
– 3″ and 6″ socket extensions
– 12mm deep socket
– 12mm box-end wrench (for getting at the lower rear nut of EGR guide tube
– Flat screwdriver
– Pliers
– paperclips – the type that is in an “X” since they’re the biggest
– Large Phillips screwdriver
– Hacksaw blade

Consumables:
– Lower EGR guide tube gasket part # 14722-38u02 $5.86 (Connell Nissan prob rip me off)
– Upper EGR guide tube gasket part # 14722-38u01 $3.75 (@OC Nissan in Garden Grove)
– IACV gasket part # 23785-AD100 $3.88
– TB gasket part # 16175-31u01 $3.65

What they look like:

The brush is a heater chute cleaner, but I didn’t know the EGR guide tube was only the size of a finger

Here’s a picture of the engine bay labeled for future reference:

Steps – Airbox:
– use 10mm box ends to remove Neg battery terminal and then positive
– disconnect MAF
– detach hoses on airbox (next to the “MAF sensor” label in pic)
– Undo the 4 clips holding the box w/ the air filter not shown in pic
– use pliers to slide airbox hose clamps off – squeeze them all the way will make them slide a lot easier
– Pull of the 2 big hose and a small hose (tubing really)
– Loosen the big hose clamp next to the throttle body
– Lift airbox out

It should look like this:

notice you can see one of the large airbox hoses and the rubber tubing

IACV:
– Remove the 3 electrical (in my case) plugs to the IACV
– Remove the bracket that holds the rearmost plug
– screw bolt back on IACV to prevent loss
– use 12mm sockets to remove the 3 bolts that hold the IACV
– Pull IACV off and remove gasket if it sticks. Your engine bay should look like this now

EGR Guide Tube Removal:
– Unclip the large coolant hose clip (2 pictures up) with a flat head screwdriver
– Locate EGR guide tube – it is attached to the plug whose bracket you just removed
– Locate the lower rear stud of the EGR guide tube not be confused with the EGR tube that is located forward left of it
– Hacksaw the non-threaded part of the stud off (you need ~ 3mm off of it to get egr guide tube out), this is for me the most painful step as I had to do it with a hacksaw blade – can’t fit a whole hacksaw in there
– leave the 2 upper EGR bolts alone – it’ll make removing the lower ends easier
– Get in with your 12mm box end to undo the nut – you’ll likely only get one wrench tooth position’s worth of rotation each stroke but it comes out fast, you can turn it with fingers
– Carefully remove the nut and 2 washers 1 by one as not to drop it
– Use your 12mm deep socket to remove front lower nut of EGR guide tube
– Also remove the nut and 2 washers one by one
– Use your 12mm socket to remove the 2 upper bolts of the EGR guide tube
– Pull EGR guide tube off
– Remove gaskets with flathead if needed – my lower one was quite stuck, spray it w/ carb cleaner

Here’s a pic of how I attacked the lower front nut of EGR guide tube:

At this point, your biggest problems are over, you just have to clean the parts and reinstall them. Use the TB cleaner on intake, TB, and stuff attached to it, MAF cleaner for MAF, and carb cleaner for everything else. There are 3 things to take off of the parts you have for as easy thorough clean:

– IACV – remove the little drum that’s held on by 3 screws
– TB – remove the large hose so that the MAF is closer to get to
– EGR guide tube – remove temperature sensor to clean and clean out all orifices

Cleaning Tips:
– Use a knife and straightened paperclips along with carb cleaner to clean our EGR guide tube
– Toothbrush works well for cleaning TB and IACV, but it scrubs away from you or you’ll get dirty

Here’s a clean EGR guide tube for kicks:

When you’ve put everything together again, it’s time to adjust idle speed:
– Warm your engine up to operating temperature
– Unplug the 2 TPS plugs in the 1st engine pic
– Turn black idle speed adjustment screw on the IACV, in the pic right under IlyaK’s post (also in 1st engine pic), clockwise to lower idle speed and CC to elevate it

Troubleshooting:
– I have heard that if you forget a vacuum hose, you will get high RPM idle
– I forgot to tighten the large EGR tube (the one I mentioned “not to be confused with”), it also gave me high RPM idle and excessive engine compartment heat – coolant temp reads normal though

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