PO401 and EGR/air intake manifold with pictures (2 Viewers)

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So a few months ago I got a P0401 and did a lot of reading on mud and the FSM in an attempt to get things lined up for taking care of the problem. I am a poor mechanic but want to learn so figured I'd give tackling this problem a try.
I had a week to get it done (it shouldn't take that long) and didn't have time to do as much diagnosis/trouble shooting as I would have liked but was pretty certain my EGR regulator and valve were ok. I wasn't sure about the VSV and decided to replace it as well as the other components as they weren't looking great. I just didn't want to have to come back and do things over.
I'm posting this thread, not as a way to diagnose what is wrong, but more as a thread to show what I did with lots of pictures in the attempt that anyone else running into this problem will have some pictures as references. If I describe anything wrong or lable anything wrong please PM me so that I can fix it for other people's sake. I am just hoping to contribute back a little for all that you guys have done for me. So here goes....

Heres a list of links I found helpful in doing this project.

https://forum.ih8mud.com/80-series-tech/540650-throttle-body-baseline.html
https://forum.ih8mud.com/80-series-tech/65702-code-p0401.html
https://forum.ih8mud.com/80-series-tech/363575-p0401-defeated-pics.html
https://forum.ih8mud.com/80-series-tech/203948-replacement-vsv-spanish.html
https://forum.ih8mud.com/80-series-tech/295289-9-times-out-10-po401-code-fixed.html

Here is a link that seems like an easy way to test the VSV for EGR and moving it from under the manifold. I hadn't seen this post when I had started working on mine. I may move it later if I ever have to go back in there.

https://forum.ih8mud.com/threads/checking-vsv-for-egr-easy-way-p0401.211364/

Here's a list of the parts I ordered from Cdan (I did the PHH and a coolant flush per e9999 thread as well during this project):

EGR system:
EGR Vacuum Modulator (Blue top)
VSV for EGR
EGR valve
EGR valve stud bolts and nuts that go into the air intake chamber x2 (mine were slightly stripped from a previous dissasembly with the wrong tools)
Vacuum hose
EGR gasket
Air intake gasket x2

PHH:
Gates greenstripe

Fuel injector cleaning:
Upper O ring and rubber grommet x6 (comes with cleaning service)
Lower seal on intake manifold side (fuel injector insulator) x6 (came with cleaning service from RC engineering but not others that I spoke with).
Gaskets for banjo bolt (union bolt) on Fuel Rail x2

Other maintnence:
Gas Cap
Air filter
Gas filter with 4 gaskets for the union bolts (came with filter)
PCV valve and grommet and hoses

First a little overview of car anatomy. In the first picture.

1. EGR Vacuum modulator
2. EGR valve
3. EGR gas temperature sensor
4. Brake booster vacuum hose
5. ?
6. Throttle body position sensor
7. Fuel pressure regulator
8. PCV valve and PCV hose #1
9. PCV hose #2


In picture #2.

1. Throttle body
2. Upper air intake manifold.
EGR 1.jpg
EGR 2.jpg
 
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For dissassembly of the EGR vacuum modulator and EGR valve.

The EGR vaccuum modulator is held in by the vacuum hoses and a metal clip. Disconnect and lable the vaccum hoses and remove the modulator from the clip.

Next unscrew the the 2 nuts holding the EGR valve to the upper air intake manifold.

Loosen the EGR Pipe nut being careful not to damage the wire harness with the handle of the wrench as you unscrew the nut.

In order to remove the EGR valve, the 2 EGR bolts need to be unscrewed from the air intake manifold. I tried the "2 nut technique" but messed up the bolts and nuts. I recommend just getting a star shaped socket to unscrew the bolts. I found a set at Harbor Freight for 9 bucks. A 5mm socket also sort of works.

There is a gasket between the EGR valve and intake manifold that is supposedly not re-usable. It has a tendancy to want to fall into the engine bay (especially when putting things back together).
EGR 3.jpg
EGR 4.jpg
EGR 5.jpg
 
Next I basically disconnected the vacuum hoses and labled them and disconnected the air cleaner hose from the throttle body and air filter canister with the MAF housing all as one piece and set it aside.

I also disconnect the electronic connectors from the various sensors.

I recommend changing out the PCV valve and hoses if you are doing this job or if it hasn't been done recently. It is relatively cheap and easy to do. My hoses were cracked.
EGR 6.jpg
EGR 7.jpg
EGR 8.jpg
 
I then disconnected the following from the throttle body.

1. Accelerator cable
2. Cruise control actuator cable
3. Throttle body cable.

It is important to mark the cables and nuts so the cables can be placed back the way they were. The accelerator cable will affect the gas pedal and idle speed if not connected as it was. The cruise control actuator cable won't maintain your same speed when the cruise control button is set if not properly adjusted. You may actually accelerate or decelerate once setting cruise and taking your foot off the gas. And the throttle body cable will alter your shift points if not re-connected properly. I still have some adjusting to do on the throttle body cable to get things back to normal.

Loosen the nuts and then release tension on the cables by rotating the pulley/spring apparatus and then slide the cable ends out of their holders.
EGR 9.jpg
EGR 10.jpg
 
If I remember correctly, at this point you can take off the throttle body from the air intake manifold by unscrewing the 4 bolts that hold it in place. There is a gasket between the throttle body and manifold that should be re-placed.

2 of the bolts are a little hidden.

There may be some vacuum lines that need to be removed at this point to fully take off the throttle body.
EGR 11.jpg
EGR 12.jpg
EGR 13.jpg
 
At this point you can then take off the upper air intake manifold. There are 6 bolts and 2 nuts holding it to the lower intake. Some can be taken off from above in the engine compartment and some you have to crawl under the vehicle to access via long extensions on your wrench. I didn't get too many pictures of this phase. Using different combinations of extensions and different wrench handles you can get it done.

The location of the bolts is pretty predictable. In the first picture the circles are where the bolts are and the squares are wher the nuts are - all of which are under the lower air intake manifold.

I found having the intake manifold stay loosened as well as the oil and tranmision dipsticks and power steering resivour tank unbolted helps free up some room.

Once the bolts are taken off the upper manifold can be taken off. There are 2 gaskets here as well that need to be replaced.
EGR 14.jpg
EGR 15.jpg
EGR 16.jpg
 
Wow, looks like you've been pulling some oil through there. Time for a catch can I think.
 
I was peaking through the throttle body on my 95 this last weekend and saw pretty much the same gunk caked on the inside of mine. You have done a great job of labeling these items for us noobs by the way. Keep up the good work!
 
Wow, looks like you've been pulling some oil through there. Time for a catch can I think.

Yeah, I thought about that, but was still undecided which catch can to go with. I could probably do the cheap method that everyone seems to be doing until I get a real one, but then I just bought the new PCV hoses from Dan and don't want to waste them. Bad logic I know....
 
After getting the upper air intake off and throttle body off you can see how much oil there is that gets mixed in from the PCV hose with the recirculated exhaust fumes. Looking back at where the PCV hose connects to the manifold in previous pictures you can see how much oil is there.

I then stuffed the lower air manifold holes with paper towels to prevent bolts etc from dropping down in there.
EGR 17.jpg
EGR 18.jpg
 
Next you have some cleaning to do. I used Carb cleaner (same thing as throttle body cleaner) from the local autozone. I tried to get as much of the oil and carbon deposits out as I could, especially in the smaller ports of the manifold chamber.

The first 2 pictures show the usual areas of carbon blockage as they are the passages with the least space. The dashed line is a straight passage connecting a vaccuum hose from the top of the manifold to the bottom. It is circled in the second picure.

The last picture shows some of the EGR and EVAP components.
1. VSV for EGR (I replaced mine in this project)
2. VCV for EVAP
3. Check valve for EVAP (make sure it is facing as shown in the picture when you put things back together. It is a one way valve and you can test its function by blowing on either end.
EGR 19.jpg
EGR 20.jpg
EGR 21.jpg
 
While I had things this far apart, I decided to pulle the fuel injectors as well and have them cleaned by RC engineering. I was able to drive them down to them and pick them up the same day. They did a great job.

To get the fuel rail off, it isn't much more work at all.

1. Simply unbolt the banjo bolt/union bolt holding the fuel inlet pipe to the fuel rail (the bolt is seen in picture 2 and circled/labled #1 in picture 1). There are 2 gaskets here that aren't re:usable. They look like aluminum washers.

2. Disconnect the electrical connections from the fuel injetors being careful not to damage the wiring or connectors. Some of them are highlighted with red squares in picture 1.

3. Unbolt the 3 bolts that hold the fuel rail to the injectors and lower air intake manifold. They pass through 3 plastic spacers that can fall out if you don't realized they are removable. They are seen in the last picture. The little black gaskets are the old lower insulators for the fuel injector that sit in the lower intake manifold. The other 2 grommets/insulators are on the injector/fuel rail.
EGR 22.jpg
EGR 23.jpg
EGR 24.jpg
 
You can now carefully lift the fuel rail with the injectors out of the engine bay (picture 2 is what it will look like - only less clean). They are not screwed in or bolted in and are simply held in place by the fuel rail and grommets. I also plugged up the fuel injector holes with paper towel to keep things from dropping in there as well. Some of the lower insulators were stuck against the aluminum of the lower intake manifold and took some work to get out and ready for the new insulators to be put in.

Disconnect the fuel injectors from the rail and send them off to get cleaned.

Wait for them to get back and admire how shiney they now look. :grinpimp:
EGR 25.jpg
EGR 26.jpg
 
Great thread! Very well done.
 
Great job. I did the exact same thing but didn't have the patience for pictures or a writeup. I think this method is preferable over the reaching in method, but that's just my opinion.

I opted to skip the injectors as I had to turn this around in a day, but I did do the fuel filter.
 
A job done right! Nice work
 
I almost forgot to mention to take time and admire how well your injectors worked before cleaning. They really weren't all that bad at 167,000miles. The #3 was "dripping" but the rest looked good. If it wasn't for the #3 I would have felt I had wasted the money on the cleaning and so would the :princess:. Picture 1 is the results from RC engineering.

Since I was getting them cleaned I figured I should replace the fuel filter as well while I was there and had the part ordered along with the other EGR components. I don't have any pictures of that proceedure but it is straight forward apart from the difficulty in accessing it below the lower intake manifold. There are 2 bolts holding it in and the ingoing/outgoing fuel line from either side of the filter. There are 2 banjo bolts/union bolts with 2 gaskets per bolt that are just like the fuel inlet pipe on the injector rail.
EGR 27.jpg
 
After getting everything cleaned up it was time to get things back together starting in reverse. Place the fuel injector insulators into their cleaned spots on the lower intake manifold (picture 1 and 2)

Install the injectors directly perpendicular with their new o-ring and grommet into the fuel rail with a twisting motion. Face the electronic connectors upward (picture 3).

Place the 3 plastic spacers in their positions on the lower air intake manifold (where they should go is seen in the red square boxes in picture 1).
EGR 28.jpg
EGR 30.jpg
EGR 29.jpg
 
Position the fuel rail with the injectors into their proper position. Place the bolts throught the fuel rail and check that the injectors rotate smoothly before tightening down the bolts (picture 1).


The FSM states to torque to 15ft.lb.f. Make sure your torque wrench is working before doing so or you'll end up waiting for a few days to get a hard to find bolt mailed to you :doh: (picture 2). I was lucky to get it out in one piece.:)
EGR 31.jpg
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