I just got the 0302 code and I suspect its due to a carbon build up...at least I hope so because I do not want to go replacing the actual valve or solonoid.

Anyhow I would like to clean the intake plenum port and guide tube (is there anything else to clean BTW?), but I really do not want to remove the intake plenum as njmodi has.

I noticed there is an alternate method though...it can be found here: http://autoclinic.net/article/imports/nissan_p0400.htm

It involves removing the IAC plate and some how accessing the EGR port...can anyone help expand on this? Thanks

 

You can use the alternate mechanism as a quick fix, but you can't really get to the tube very well that way. You should be able to get some of the plenum EGR port build up cleaned up from the IACV hole (once the IACV is removed).

Unfortunately the only way to get ALL the build up out is to pull the plenum and in some cases pull the guide tube out as well. I was able to clean out the build up in the guide tube without removing it - most of my buildup was in the plenum port and at the end of the guide tube.

Have you ever pulled the plenum off before?

 

No I have never pulled the plenum off before...it looks like a very tricky task that involves removing a lot of other components, correct? Also don't certain gaskets need to be replaced?

 

It's not hard as much as tedious. And although it looks like you're taking apart half and engine-bay, it's really not that bad.

I would recommend replacing the following gaskets:

TB gasket
IACV gasket
Plenum gasket
EGR guide tube gaskets (at plenum and at egr valve)

I replaced all of mine. It doesn't make sense to reuse the gaskets to save 15 bucks and then end up with a leak that takes a lot of labor to fix.

If you do end up pulling the plenum, check the valve cover gasket for seepage and replace that too, as well as the spark plug seals.

The bottom line with removing the plenum is, you have to work slowly, patiently and be ready for some frustrating hoses, clamps and angles. The nuts/bolts are fairly straight forward to get to/undo, but the rubber hoses and those spring clamps on the coolant lines can be quite challenging. Again, this is not a job you should go into with the intent of knocking it out. I spent 2 hours disassembling everything including the valve cover. I can probably do it in an hour now.

Reassembly - I was working slowly and carefully, and had a particularly tough time with the coolant lines behind the plenum. The rest was straight forward.

I would allocate the better part of a weekend to do this - you may not need it, but at least you won't feel rushed.

I would recommend disassembly/cleaning one day and then reassembly the next. But that's just me. There are members here who could have the plenum off, EGR cleaned and everything reassembled in 2-3 hours. I have done the job 3 times (long story).

1st time
Disassembly/cleaning: 2hrs
Reassembly: 2 hrs

2nd time
Dissassembly/cleaning: 1hr
Reassembly: 2 hrs

3rd time
Dissassembly/clearning: 1hr
Reassembly: 1.5 hrs

Get a Haynes - it (at a high level) goes through everything that needs to be removed to get the plenum off.

I remember the following:

intake
TB
IACV
EGR guide tube
Throttle cables
Coils
Harness that runs on top of plenum
Breather hose on top of plenum, coolant lines
Purge valve
FPR

 

I have a question about the EGR guide tube. When I cleaned my intake a while back, I took the plenum off and was doing pretty good until I tried to remove the guide tube to change the gaskets. The bottom nut that holds the tube on was being blocked by some exhaust tube that was about 1.25" in diameter. I got the nut loose all the way to the end of the stud, but then I couldn't get it between that tube and the stud. When I tried to loosen the large tube from the exhaust manifold with a large wrench, I found that I couldn't make it budge at all, let alone enough to get the nut off. So, how do I do it?

PS, the plenum where the guide tube entered it was completely filled with rock solid carbon buildup, but a small flat-head screwdriver showed it who's boss.

Thanks

 

woo hoo.. so it wasn't just me. I had EXACTLY the same problem. I got both lower nuts free, but I could not get the lowest nut to clear the larger EGR tube... so I just left it... .. I cheated and was NEVER able to pull the EGR guide tube (the smaller tube that connects to the plenum) off the car... but as you mentioned, most of the blockage is in the plenum port and at the very end of the smaller tube (plenum end). So I really didn't have to get the other end off/cleaned. I would have liked to, but after putzing around for too long trying to break the larger tube flare nut free, I gave up and moved on.

You need what is called a crows-foot wrench for the larger tube - its' impossible to get it broken loose any other way. And you have to loosen it at both - on the manifold as well as on the valve.

So as long as you cleaned out the plenum port and the smaller tube and the 0302 code hasn't come back, just

 

I agree about only needing to clean the port and the top end of the tube since I also have not had the 0302 code come back since I did that cleanup. I also changed the PCV valve while I was in there. I guess that tube and the stud were the only thing (except for maybe the knock sensor location) that Nissan has "pulled a Ford" when in the engineering stage. In case you don't know what "pulling a Ford" means, it's when you design cars with parts in all of the wrong places and it makes changing an alternator require removing the entire right side suspension, y-pipe, and driveshaft.

 

Kingrukus - I used the autoclinic article you referred to when I got 302 code . I pulled
the IAC . There is a trough inside the plenum at the egr port. I found it fully packed
with crud. I picked it loose with a coat hanger , reached in with a finger - the crud
stuck to my finger till I could wipe it on a rag. Did this for over an hour until trough
was clean.Probably got 1 or 2 ounces of gunk out. I put the IAC back on , warmed
up the engine and manually operated the egr valve .The engine stalled as it should,
which indicates a path has been opened for egr flow. I did procedure when I had
around 190 k miles and all is still well at 240k. If cel returns in future I'll remove and
clean egr pipe as well, but so far it been fine for 50k.

 

I'm interested in doing this, as I have neither the money for a mechanic to clean the EGR system nor the know-how to pull the upper intake manifold, ant the autoclinic link at the top of the page is down. Does anyone know the location of a write-up or could lay out what this involves?

EDIT:Nevermind, I just went and poked around behind the IACV and saw what was up, and it's nasty. I also found an good, if photoless, writeup by jimmy9252 in http://forums.maxima.org/showpost.ph...3&postcount=53
Sorry for the worthless bump.

 

There is a long flexible wire you can get and attach it to a drill. Put the wire down that tube and let the power tool do the rest. All you need to do is loosen it up in there where it gets clogged, usually at the bend.

 

what is plenum? and where is the acv and hole

 

your screenname is justified

 

http://forums.maxima.org/4th-generat...ing-p0400.html

 

hindsight but you wonder if nissan ever put 75000 miles on this engine in testing- you would think they would have noticed this problem.

 

whoever said you need to remove the fuel pressure regulator and coils is wrong. YOu can see everything you need to remove by looking at it and the only items that are hidden are the brackets on the rear(just feel around not hard) and the coolant line. THe first time takes longer because you have to figure out what all needs to be removed. Be careful with the harness when folding it out of the way. Its old and brittle

 

they did and removed it in later models. Get a block off plate if you don't want to clean anymore. Mine wasn't that clogged after 16 years so I dont know why some peoples seem to to be more clogged than others

 

whats up dude? i can help you with it, its not THAT difficult removing it... i've had my 00vi on and off about 4 times and i've gotten used to doing it well. the worst part is getting the 2 bolts off and the bottom. you gotta have a sander or small saw to trim one of the bolts because its in accessible otherwise. that part is the worst part, everything else is just step by step take off/put on.

 

the egr tube on the 2000 model is much improved, just one smooth L bend... not like the snaky 4th gen one. even after 250k+ km of usage there's no build up.

 

+1 ... kingrukus this should help a lot. i'm still around to lend a hand if needed, pm me on tmec if you like.

 

The original post was from 2005.

 

what i did to get the nut out was push it up till it popped out then after the washer wouldn't come off so went to the dollar store and bought a cheap three piece hacksaw blade to cut about a milimeter off the tip of the screw. i ended up breaking all three hacksaw blades but got it done took me about 30 minutes to cut all the way through .what was strange was that my tube was clean after 200,000 miles. i still dont know what could be causing th 0302 code.

 

lmao didn't see that... i was wondering why he just posted here instead of here and on the toronto maxima site