Dexter

EGR System Hi/Low Flow <- what does that mean? and how do I fix it.

Dexter

ok, i've asked around and was told to check the egr solenoid valve, as they tend to go bad right around the mileage my car is currently in. what else should I check?

nhaven

could be a clogged egr tube.

f550maranello2

iTrader: (2)

egr tube to the upper intake manifold.... its probably solid

2da mizzax

iTrader: (4)

there instructions are thorough. only adjustment i made was instead of taking off the large pipe with the EGR attatched (which they say you have to in order to get teh small pipe off) i removed the studs from the large pipe right where the EGR is which allowed me to pry the large pipe down and allowed me to remove the small pipe.
http://forums.maxima.org/showthread.php?t=90535 post#37

here is a slightly different way of doing it with some pics.
http://forums.maxima.org/showthread....58751&t=496494

clean it before you change the valve as changing the valve with a blocked tube will have no effect and be a waste of money if the valve was good to begin with. you may want to just buy a new tube. i think they are around $30. soulc be wrong on the price.

Dexter

tested the EGR valve by watching it when I rev, it doesn't do anything so it's either clogged, or not working. have yet to test the solenoid. will test solenoid and hopefully one of the two is the source of the problem.

But I won't be able to tear through until the weekend to repair.

2da mizzax

iTrader: (4)

never knew you could sit and watch the EGR valve move.

Sounbwoy

iTrader: (2)

I have a thread floating around here somewhere too and pics:
Look here

Dexter

according to the haynes manual the diafragm (or however you spell it) should rise up a bit when you rev it in N if it's working, this is pre-97, 97 and up it doesn't move at all so unless a post 97 egr valve found it's way into my 95...

Dexter

anyone know where I can find a guide as to how to remove the EGR valve, tube, and solenoid? Factory Manual, Haynes (my Chilton got pwned!), Site?

2da mizzax

iTrader: (4)

Here are some instructions for pipe cleaning. only adjustment i made was instead of taking off the large pipe with the EGR attatched (which they say you have to in order to get teh small pipe off) i removed the studs from the large pipe right where the EGR is which allowed me to pry the large pipe down and allowed me to remove the small pipe. Hope for lots of rust on these studs so the stud will come out instead of the nut coming off.
http://forums.maxima.org/showthread.php?t=90535 post#37

here is a post with some pics (but the instructions are not as good.
http://forums.maxima.org/showthread....58751&t=496494

the clogged pipe is most likely the source of all of your headache. did my other max yesterday and it took 2 bottle of TB cleaner, 1 can of MAF cleaner, 1 coat hanger and about 3 1/2 hours. I took off the TB, IAC Valve MAF etc and cleaned them all. I would reommend doing this as it is probably needed and removing all of that makes getting to the small EGR pipe mucheasier. a couple of tips:
a) remove the sensor (what i assume is the flow sensor) from the small pipe once you get it the small pipe off. a set of vise grips works fine.
b) do not just clean out the openning of the tube. use a wire brush pipe cleaner or bent hanger or something to get all of the way into the tube an most of the restriction is there and not at the opening. (let the TB cleaner soak in there to soften things up a bit.
c) when taking off the IAC Valve, there is a little bracket that blocks one of the bolts, take that bracket off (it is a 10mm bolt). dont just use an open ended wrench. that bracket (and the plug attathed to it) is the other end of the sensor on the small tube and makes it easier to remove.

after cleaning all codes are gone (except the 02 sensor) which i hope was tripped by the TB cleaner but is prob just bad.

Sounbwoy

iTrader: (2)

found it!
http://forums.maxima.org/showthread....52#post4931652

Dexter

well looks like i'm gonna have to shop for a coupe of crow's feet...

thank god theres a way around removing the intake manifold since all the work will b done outdoors and it's damn cold right now. I might just replace the pipes and send the clogged ones (which are hideously rusted btw) to scrap yard hell.

2da mizzax

iTrader: (4)

Unless you plan on cleaningg out the large tube (which is usually never clogged) no need for crows feet. Taking off the large tube from the exhaust manifold looks like mission impossible (to me anyhow). thats why loosening and prying is so much easier.

Dexter

the smaller tube is inside the larger tube right? If I can actually manage to get the larger tube off it wouldn't hurt to check though. any idea on what size bolts are holding the part under the valve?

2da mizzax

iTrader: (4)

its not inside. they are 2 seperate tubes. you are right about it not being a bad thing if you can get if off. no idea which bolts you are referring to.

Dexter

i'm refering to the bolts under the valve. did you remove your intake to get clearance (seems like a good idea to me)?

2da mizzax

iTrader: (4)

didnt touch the intake. it may make it easier for removing the larger tube but i didnt take mine off.

Dexter

EGR Valve

step (?) 20, line 7, column 13: "Caution: Never wash the valve in solvents or degreaser - both agents will permanently damage the diaphragm."

I got a C in Chemistry so I MUST ask, is Carb Cleaner either of these?

2da mizzax

iTrader: (4)

yes. carb cleaner (and you should be using throttle body cleaner not carb cleaner) is a solvent/degreaser. carb cleaner will remove a protective coating from your throttle body.

Dexter

Ok...then why does motorvate.ca say it's ok to use carb cleaner to clean out the TB?! and I can't find "TB Cleaner" anywhere...

Update on EGR tube: Snap-On truck is in my area on Fridays and thay didn't come this week (go figure!) so I'm gonna pry the tube and clean out what I can with the wire-wheel and try to remove the whole tube when Snap-On truck gets here and I buy the crow's feet I need for that, weather permitting...

2da mizzax

iTrader: (4)

STP makes a TB cleaner. Autozone, pepboys, etc etc all sell TB cleaner. the STP one says "intake and throttle cleaner".

Dexter

UPDATE: Removed intake, but there are 2 hoses blocking the EGR nuts and it's too cold to work for extended periods of time, I gave up and decided to take it to my mechanic and tell him to clean out (or replace whichever is easier) the EGR tubes, It seems my mechanic will have a merry christmas on my expense this year.

2da mizzax

iTrader: (4)

didnt need to remove the intake manifold. and the 2 bolts holding the large pipe in place would have allowed you to pry it down and take off hte small pipe. how much is he charging you?

Dexter

I didn't remove the manifold, just the stuff that's removed to clean the TB. Did you do this in the winter, cuz I couldn't even think straight with this cold. I dunno how much he'd charge me but he quoted me 80+part, for a y-pipe swap so unless he gives me a "holiday price" I don't expect it to be more than $100 if he does I'll just get a fan heater and some extension cords to keep me warm and do it myself cuz I'm very broke and trying to save for x-mas.

Sounbwoy

iTrader: (2)

I can understand working in the cold, BUT, it's not as bad as you think. As we've said before, it's a 90% chance that the EGR tube (the pipe at the back of the IM that goes down) is completely clogged. The valve itself is probably fine (mine was and I had never changed it until I had my issues). Most people who have their mechanic do the work, have the code come back b/c the dude only changes the valve and does not clean the tube. So if you did take it to him, be VERY SPECIFIC. Chances are he's gonna remove the IM and charge you $400.
Just take your time, LOOK at everything and you will be fine. Three or more of us have pictures to help guide you so use it.

FWIW-if there's a Moderator looking around, the EGR sticky does not appear to be working. It goes to Photobucket, but is asking for a password....

2da mizzax

iTrader: (4)

believe it or not, he will prob charge a lot more. Y pipe is dead simple if you have a lift. This takes a little more time. If you were close i would help you through it. like Sound said, take your time. it actually moves faster. you dont make hasty mistakes. find out how much he is charging, and if its a ton i will email you a detailed writeup or something. i understand the cold thing though jumping jacks maybe?

Dexter

yeah I'll let him know I just wanna clean out the EGR tube and not replace it, I don't think he'll charge me alot for it, hopefully. He's the type of mechanic that if you make his job easier and tell him EXACTLY where the problem is and how to fix it he'll charge as little as 50 bucks depending on the issue. If you could send that write-up anyways I might check the forecast and hope for a warmer day and fix my car then.

chillin014

iTrader: (67)

i have my old egr valve which still holds vacuum perfectly fine. if anyone thinks their valve is bad and needs one PM me

Dexter

i think my pipes are just clogged, but I'll let you know if problems arise elsewhere.

dallas0593

iTrader: (10)

here's a pretty good link to cleaning it out.

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

2da mizzax

iTrader: (4)

mail. dont forget to clean the openings on the plenum etc when you get the pipe off. (i almost forgot that when i did my first one).

jremignanti

For anyone who has an 0302 code:
With the car warmed up and idling, if you manually push up the diaphragm, does the idle get very rough or even stall?
Mine does, which would make me think that enough exhaust gas is still making it throught that passage to be effective. Anyone who has done the plenum cleaning had this behavior beforehand?

My issue seems to be that the EGR valve itself is not lifting. The FSM says that if you rev the engine in neutral with the engine already warm that you should be able to feel the valve diaphragm lift. I don't feel any lifting at all when I do this. The valve holds a vacuum if I put my finger over the vacuum port and push up the valve. Has anyone actually felt the valve lift when revving or is it really subtle?

My solenoid valve is working, I removed it and tested it. But it seems like I'm not getting enough vacuum to the EGR valve to lift it properly. Which seems to point to a problem with the vacuum strength itself (maybe a clog), the BPT valve cutting the vacuum, or the EGR valve spring being too stiff.

Anyway mine doesn't exactly point to clogged pipes as the problem and I was wondering if anyone else had seen the same thing.

chillin014

iTrader: (67)

the car is supposed to die when you push up on it. your problem is the same as mine...none of my pipes were clogged and neither was my intake manifold which i've replaced now anyway. someone showed an article suggesting that it cold be a result of low backpressure and i do have an aftermarket y pipe and exhaust so i could see where there would be less than stock. I replaced the valve itself with an OEM one and nothing changed. at that point i gave up because it became rediculous....another good excuse to put in a 3.5....

Sounbwoy

iTrader: (2)

I would assume that the pipes would be the problem if there's not enough vacuum. FWIW, take a look at this pic.
If you look the part where I have circled in Red, you will see that that piece of hose is all messed up. It helps to eliminate all possibilities. This wasn't the main problem why I got the code, but it had to be contributing to it. A new piece of hose fixed it. That hose is the ONLY thing that connects it to the other valve. If that is fine, then I'm not sure what the issue would be. That pipe also had some blockage but it wasn't solid like the big tube was.

chillin014

iTrader: (67)

the tube you pictured had a HUGE hole in it on my car when i was replacing stuff and i thought DAMN THATS GOTTA BE IT...right after i bought the stupid 180 dollar egr valve, but replacing it didnt yield any better results

jremignanti

hey chillin and sounbwoy,
did you guys ever feel the valve diaphragm lift when you revved the engine? If you did, how much does it move when you rev? I can't feel mine moving at all.
I'm going to swing by autozone and borrow one of those vacuum pumps to see if I can get the valve to move with that and how much pressure it takes and then compare that to the amount of vacuum I'm getting to the valve. That should tell me for sure if the EGR valve is bad or if the vacuum source is too weak.
Which would then have to mean that the problem is somewhere in the vac lines or it the BPT valve since that cuts and controls the vacuum to the main egr valve.
ugh... too many valves... at least I understand EGR now. that hasn't help me find the problem. btw, I failed my inspection last month so now I'm on the clock to fix this one.

2da mizzax

iTrader: (4)

if you get 0302, what makes you think its the valve itself and nto a clogged pipe? the sensor that throws the 0302 code is on the small pipe itself.

jremignanti

you're right, the ECM uses the EGR temp sensor to determine whether or not there is EGR flow during a situation that calls for EGR. If it doesn't exist or is not enough you get the 0302 code (low EGR flow) which means the EGR valve isn't opening up to allow exhaust gas back in or the pipe that takes the exhaust gas back to the intake is too clogged to allow enough flow through.
The reason I'm thinking it might be the valve or the vacuum for me is because if I push up on the valve manually while the car is idling and warmed up, the engine nearly stalls. If I kept pushing up the valve the engine would totally stall. Anyway, this seems to tell me that there is still plenty of exhaust gas that makes it into the intake through that main pipe. It looks like the valve isn't moving on its own.
I'm going to test this out a little more tomorrow if I get time and I'll post what I come up with.

JR

Dexter

UPDATE: Managed to pull EGR pipe (thanks 2da MizzaX for the walkthrough!) and it's ROCK SOLID! it will take a while to clean out so I plugged all openings to the engine to put back together tomorrow.








Thanks again to 2da MizzaX