dragonboyokada

iTrader: (1)

Appreciate the thorough write-up and pics. I'll add this to my to-do list. Thanks!

twiggy144

Justaguy, I dont think something can be done to prevent clogging. I would just reinstall the bolts that need to come off with antiseize on them , to make the next removal much easier and a quicker job.

marktab

Hi Justaguy

Yes, the process does take a while, mostly because of the awkward angle. The procedure itself it not complicated to understand or complete. No one needs advanced tools or parts for this process.

I will provide my best recommendation on how to keep it clean:

On Auto-RX -- I have used that product, and I believe it works; however, it is also an expensive product. I have more recently began experimenting with Marvel Mystery Oil with good results, and the product is more available and cheaper too. At some point, I believe that in all vehicles sludge can accumulate in an engine, perhaps in the oil pan and other places, and the only sure and complete way to maintain those areas is to open the engine and manually clean it out. We use these other liquid products for two reasons: 1) the obvious time and energy cost to open an engine, and 2) the need to prevent sludge from the outset. I believe my bulleted points are more important than special products, but you might want to also investigate Marvel Mystery Oil from their website and from other people who have been using it.

The EGR tube will fill up again no matter what anyone does, but I believe my recommendations will help maintain your engine and give you the longest time between cleanings (and when you or I clean it next time, hopefully it will not be totally clogged).

marktab

Thanks for the feedback -- please post back when you do the cleaning on your experience.

Justaguy

Does running 93 octane really help reduce the carbon buildup in the EGR tubes?

It seems like everyone in here has had to clean the deposits and I'm almost sure that they have been running on 93. Yeah??

twiggy144

I doubt it. 93 octane prevents detonation. This has no effect on long term carbon buildup.

marktab

Hi Justaguy

Again, we are talking about scientific theories here. I did NOT say that if you use 93 octane gas that we would NOT get buildup in the EGR tube. What I did say is that 93 octane gas is the level recommended by Nissan for this vehicle, and that using this fuel keeps your overall engine in the best operating condition.

Detonation is a condition which can increase the carbon buildup in the engine because the fuel is not burning in an efficient way. You can research this topic by consulting with a professional engine scientist (I am not one). Here is a website which (for example) provides information on how carbon can affect the engine: http://www.autospeednet.com/sites/3d...ewterm/3681/0/

I can interpret Twiggy144's comment to mean that 93 octane has no long-term effect on carbon buildup -- but we have to qualify the comment. Carbon will build up no matter what octane gas we use. I believe that using the recommended higher octane gas delays the rate of buildup not just in the EGR tube but more importantly in critical areas of the engine like the pistons. I previously said that carbon will build up -- by design -- in the EGR tube, and the best anyone can do is delay what will eventually happen. Good maintenance discipline leads to a better quality experience by extending the maintenance interval.

In larger view, we should keep the priorities straight: EGR tube carbon buildup will not completely stop the Maxima, and mine was operating with the yellow light on. Was my vehicle in best operating condition? No, since I was receiving the P0400 engine code. The general operation of the engine is affected by many factors, among which is Nissan's 93 octane recommendation. The gasoline choice is not the single or necessarily the most important factor which causes the vehicle to operate well, but several factors need to work together (scientifically) for the vehicle to perform best. An analogy which works is like a football team (American or international) working together -- all the parts need to be there for success, just like a Maxima requires many parts to be called an "automobile".

Anyone could disregard my octane recommendation, and choose to put other higher or lower octanes into their Maxima. However, I believe they would need to make tuning and/or mechanical changes to their vehicle if that change is their long-term choice. That topic would be for another thread.

dvpatel99se

iTrader: (1)

FWIW, I purchased my Maxima brand new in Jan 1999. I have always used 93 Octane gas in it except twice. Once my BIL filled in Regular and once I did. So, the car has only seen 2 tanks (not even full tanks) of non-premium gas.

I have had the CEL for P0400 for over 2 years now as I am too lazy to get the job done and too cheap to pay someone to do it.

So, I tend to agree with twiggy that using (or not using) 93 octane doesn't seem to have any bearing on the said carbon build up in the EGR tube.

I don't remember at what mileage I got the P0400 CEL (its buried in one of my posts here) but I currently have 92.5 K miles on the car.

marktab

Hi dvpatel99se

Are you willing to experiment with your Maxima for the next 10 years? Would you like to gain the actual experience of running 87 octane, and see how quickly the EGR tube fills up compared to your past experience? Also, would you be willing to collect data on the overall vehicle condition based on that change?

The evidence we have is that you have a filled EGR tube that you have not cleaned out -- are there other known maintenance problems with your vehicle? Your data point is that 92.5 K miles was too long to wait for cleaning this tube based on your driving habits and your climate. We cannot take mileage alone as the single operative measure of use since people are using Maximas for various reasons, including personal and commercial uses. Mileage is a proxy measure for overall vehicle use, which actually might be higher or lower than the mileage indicates.

I propose that a number of people are following Nissan's 93 octane recommendation and they don't know why in the world they are doing it. That single recommendation, as I said, is one of several well-published recommendations which together -- not alone -- help your vehicle run in best operating condition. Sometimes synergy is easier to illustrate in biological systems (like our bodies) but the principle also is true for mechanical systems.

Professional mechanics are not necessarily economically incentivized to help you or I take best care of our vehicles -- they are incentivized to fix problems as and when they happen (reactive versus proactive). If we went to Nissan, they have an even simpler solution for a clean EGR system: purchase or lease a new Nissan.

Justaguy

Okay Guys, I'm at the point where I have also removed the EGR solenoid valve (the green plug), and the EGR BPT valve.

For the EGR solenoid valve, it was very difficult to remove since the screw is at the bottom, as recommended here, I bent the steel clamper to give me more of an angle and used a flexiable socket racket 10mm. I also sprayed some PB blaster near the base of the conection of the steal and the EGR solenoid valve. After a few bruises, I got the dam nut off...with no blood.

The EGR BPT valve was a little easier. After I removed it, the little metal tube at the bottom of the BPT vale was blocked with carbon deposits. It was a little hole and a quick ***** with a tip of a nail removed the gunk. Since I have this piece off, I'm simply going to replace it...the foam around this thing is extremely dirty...I might try and open it up one day.

Now, the EGR valve...It's still on the car, I'm not sure how you remove it. The search returned about 15 pages (I image EGR is a popular search word) after going thru 4 pages and getting restless, I just have to ask..

How do you remove the EGR valve (not the tube or spacer)?

Thanks

marktab

Hi Justaguy

This thread is about the EGR tube, not other parts. I see you have started two other threads on this topic and people may respond to your question. You might want to check a repair manual too.

Justaguy

Guys, I need your help... I am putting everything back and I cannot get these two screws back in. Let me explain.

When I removed the EGR tube, the nut was so rusted that the two attached screws came off with it..after I hacked-sawed and as I turned the rusted nut, so did the screw and it came off (meaning the screw came off the holder) .
I bought myself a new set of screws and nut and when I tried to screw the screw back, it only does 1/2 turn and then I have to force it...which I did and managed to get a few more turns, but it was too tight and still had a long way to go.
So I removed the new screw and decided to put the old screw back...same thing, after 1/2 turn it won't go in anymore. I tried inserting the screw from the back and again, less than 1/2 turn it gets stuck.

My new screw that I just tried looks all threaded and I can no longer slide a nut on the opposite side. The old screw is still good as I did not want to force it.

I tried PB blaster in the screw holder but nothing...I think it's probably all de-threaded.
I've been at this for the last 2 hours and I can't give up...maybe I can get some kind of little adapter to screw it on or something...

This picture above shows the area I'm talking about...I see that screw well fasten...mine would be only in at 1/2 turn at best.

HELP please!!

Justaguy

I think I may have solved my problem....just get one of these:

http://www.nmri.go.jp/eng/khirata/me...t/index_e.html

it's a "tap and die" to make threads.

I just hope I have enough space in there...

marktab

Hi Justaguy

Wow, sorry that bolt was stuck.

I hope the tap and die works for you. Also, I'm hoping the replacement screws were metric -- but if not you can simply redo the threads to a standard screw also. Functionally, this screw and nut simply holds the EGR tube snug to the engine, and does not involve moving parts, so as long as it goes on you should be good to go. When you put the nuts on, I think putting something like WD40 on the nuts will help them come off next time, and also they do not need to be tight will all your strength, just snug enough that regular engine vibration will not knock them loose.

rdw72777

I'm still in the process of removing the EGR guide tube (dang rusted nut/bolt), but I have a question about the cleaining process for when I get there..

Is there anything inside the tube (like a filter or something)? I ask because having seen some of the carbon buildups, I'm wondering if just scraping with a screwdriver on the ends will be enough. if there's nothing inside the tube (i.e. its jsut an empty tube), could a put something like a wire hanger in there to clean out the crud in the areas I can't see? or will that harm the tube somehow?

marktab

Hi RDW

On the tube -- the construction is hard, and felt like steel to me because I did not see any crinks which would indicate it was aluminum. So yes, you can go at it with a small screwdriver (which is what I did) or a coat hanger. I like the screwdriver because I was often scraping it out (rather than chiseling, though I could have done that too). Screwdrivers often have harder steel construction (well the good tools do anyway) so that makes them a good choice for the relatively softer carbon. A coat hanger may or may not be as tough.

The cleaning process reminds me of having carbon buildup on a cooking pan (have you ever burnt something on a pan before?) and you had to scrape it out. Sure, steel wool would do the same job, but the opening is too small for most fingers. And, come to think of it, tools like the Dremel have some application bits which would work just as well. Unlike a cooking pan, the EGR tube does not have a non-stick surface, so you do not have to worry about scraping the sides. (And now that I am saying it, I wonder if some future design WOULD have a non-stick surface which would prevent buildup by passing through the carbon instead of collecting it -- there's an idea for some inventive engineer.)

There is no filter or any other pieces inside the tube, but be aware that there is a gasket on one side of the tube which you will want to keep for assembly. That gasket may or may not come off with the tube (it might choose to stick to the engine side instead of the tube). I think my pictures show the gasket. You can buy another gasket, or make one (either cutting one out or using the liquid gasket for high temperature application) -- my opinion is that if you don't destroy the gasket it could be used again, and again, and again.

And finally, since there is nothing inside the tube, you could also choose to soak the tube in solvent, or put it into a cleaning tank. However, I think it only took me about 1/2 hour. I also spent additional time cleaning each of the two ports on the engine side especially the top side port which is supposed to be a very clean world since it comes after the air filter. This EGR tube connection comes after the regular air filter because of the high temperature (therefore meaning it would have to be some type of special filter, maybe glass-based, for all that carbon, and would likely have to be cleaned much more often).

It takes much more time to figure out how to remove the tube than to clean it. And once removed, the cleaning is just like cleaning any other carbon buildup (like cleaning a outdoor grill), and the tube itself is as large as a door or drawer handle. Assembly takes less time since it is a reverse process. And of course, future cleanings should be easier once the assembly bolt has been hacked. To remove rust, you could try a wire brush, though I suspect the ones which are most rusty are the bottom ones which are in an awkward location. You could probably grease those bolts on assembly since I don't think they would wiggle loose (the EGR tube does not move). I sometimes use regular wheel bearing grease or WD-40 to install bolts which I intend to take off again sometime in the future. WD-40 generally also prevents corrosion (good too for battery connections and posts).

Cleaning the EGR tube helps the engine operate according to original design -- in my case it also smoothed the idle and acceleration in addition to removing the "check engine" light (which we all need to keep working in case our engine has a much more serious problem compared to a clogged EGR tube). I suspect too that some owners of this generation of Maxima or Infiniti I-30 may have this engine light on and be really worried about their car, and if you are reading this forum, you might want to make those owners a low offer to take their problem car off their hands.

rdw72777

Oh believe me, this I've learned. I'm now at 3 nuts removed, 1 to go. I don't even know where the 4th one is, but its supposed to be easier than the nut on the hacked stud. The 4th one is supposed to be in there somewhere, but I haven't tried yet since I just finally got the "haced" nut off last night at 10 p.m. lol

fattony

First off, thanks for this excellent post.

I didn't remove the EGR temp sensor until after I had completely removed the EGR flow pipe. I wasn't able to fit a wrench around it to break it loose while the EGR pipe was still attached.

I didn't need to remove the EGR-BPT (I think) -- this is referenced as 'device' in the pictures. Removing it would have been a PITA anyway.

I didn't have to use a hacksaw on the bottom bolt of the EGR pipe. Instead, I loosened the nut holding pipe that attaches the pipe from the exhaust manifold to the EGR valve. I then removed the EGR valve to give me more space. Once the EGR valve was gone, I was able to push the lower EGR pipe (attached to the exhaust manifold) out of the way enough to get the EGR pipe off. Man, was that thing nasty. Not only completely blocked up in the pipe, but also in the (throttle body?) where the IACV was attached. Then again, I'm at 242K miles

Again, great post and great pictures. Glad I found it.

JtzMax

iTrader: (5)

This isn't in the sticky'z why? Needs to be, awsome write up!!!!!

mikesmax

Nice write up.I am going to do mine today.

marktab

Thanks for the feedback -- from your description, it sounds like you went in through the bottom. And, I agree on the nasty carbon blockage after the end of the EGR tube (intake manifold area) and around the IACV.

marktab

Thanks JtzMax, and mikesmax for the feedback

cdmapro

I'll add this -- be sure to reset your ECU (by disconnecting battery overnight) after you finish the EGR job. depending on how long you've been driving with a blocked up EGR tube, your ECU has probably compensated the fuel injectors to account for the blockage. now with the blockage gone the A/F is out of whack, and this will cause problems.

For me it resulted in hard warm starts that began after I replaced the EGR tube (I didn't bother to clean the old one. $25 for a new one, good to go). simply erasing the EGR code did not cause the ECU to re-learn the fuel map. after 3 weeks of hard warm starts, one night with the battery disconnected solved the whole problem.

ugufru

Great thread and pics! a bit long at this point, especially after reading the sticky too, but im feeling confident about cleaning my own tube in a few weeks. i have a 1995 SE with 165k+ miles, so i figure its the next thing on my list to get rid of the EGR sensor code i keep getting. The photos are great, especially with the annotations, and its reassuring to read most of the same information in multiple threads... im going to wager that all of the reading has taken substantially longer than hacking off the end of the bolt will.... soooo much reading!

Blindsqurl

Great write-up and excellent pictures! Just finished this job, took me roughly 4-5 hours with many smoke breaks! Got p0400 and immediately went to work. Hacking the bolt is certainly the most time consuming part. No special tools required. I can pass emmissions now, no code! You do have to drive for a while to get the monitors ready and the last monitor that "readies" is the one that would detect the p0400. Thanks a bunch!

tzilla

thanks marktab for nice pictures.. had the cel on for almost 8 months.. while at it i cleaned TB and IACV and everything around it. unfortunalty i could not remove the 2 bottom boths despite trying various tools. 2 bottom bolts were completly rusted out and did not want to risk by breaking the bolts. checked around with dealers and found a reliable dealer in nj who agreed to remove and replace the egr tye for 240$. i supplied a new tube, nuts, bolts, gaskets, etc ( since dealer wanted to charge another 50$ (1/2hrs) for cleaning). Parts were about 30-35 with Daveb. 240$ IMO is a very good price. it's really a hit or miss with the price qutoe as there is no estaimate in the workshop book. hopefully the light will stay away so i can complete my inspection. later this month.

Mechanically i am okay in the intermediate range. i have been learning to work on my car. IT saves a lot of money!!

tzilla

went to inspection and got a brand spanking new sticker valid till 9/2012. could not be happier. after about 200 miles since cleaning the tube cel has not shownup!

marktab

Thanks Tzilla for posting -- glad it worked out

ugufru

I've had ongoing starting problems with my 1995 SE, along with various CEL codes that eventually led me to threads that suggest I try cleaning my EGR tube. I finally got around to doing that this week, but even at 165K, it actually didn't appear to be very dirty -- not clogged by any means. I cleaned it out, tested the related temp sensor, and put everything back together. The starting problem still exists (it cranks and cranks and finally sputters to a start -- usually when the weather is cold and the car has been sitting, though sometimes it does this hot as well). After this last round, I'm getting P0400 (first time). Previous codes I've had are P0340, P0120, P0150, and P1400. We tested the Cam Position Sensor and it checked out. TPS was replaced a few years ago. I have not tested the EGR solenoid yet. These other codes have not returned, though I'm sure the O2 sensors need replaced. Once it starts, the engine runs well -- this is just a starting problem. I'm struggling to figure out what to try next... any ideas?

myblzurchn

I kind of wish I hadn't read this thread now I am not going to be able to stop thinking about cleaning mine (over 220K and as far as I know never been done). I'm not really looking forward to it being that I live in one of the saltiest cities out there, lol. (SLC)

marktab

My recommendation -- post your question as a new thread and see if someone has an answer.

In my case, I messed up my starter: I started the car when it was already running (and I know I did it a few times). I took the original starter apart and cleaned it out -- that fix worked for a while. However, I again had problems, and someone jump started me. I decided against trying to clean it out (again), and instead, replaced with a rebuilt starter. No starting problems since then

marktab

Even if you don't have engine codes, I'll bet your tube is mostly if not completely blocked. Look on the bright side -- at least you can clean out the intake area around the IACV mechanism.

ugufru

Noob->Me == Can't start threads

I still have a few more posts to go before I can do that. There's been a ton to read, and I've been reading for months, but until I can make something like 15 posts (on other people's threads) I won't be starting any threads of my own.

I've just disconnected my battery tonight, and so tomorrow I will see if resetting the ECU has any positive effects on my starting problem. The rest of my reading suggests I take another hard look at grounding my starter and/or bell housing. I've already done this, but I understand that it's worth trying heavier gauge wires.

LoKeyM4A3

Going to tackle this job over the holiday weekend, thanks for the detailed instructions and pictures!

Dillano609

I can't believe how ironic it is that you mentioned that nut, the one on where you have to hack the bolt. I am having similar issues with trying to get it off. I'm letting it soak in WD-40 and hopefully I can break it loose because I don't have a torch. As for keeping it clean, I recommend using a fuel injector cleaner called Techron. It'll keep your fuel injectors healthy and keep contaminates from building up in the EGR. Unfortunately, I just bought this car and have to start all over again keeping it clean (After I'm done with this specific maintenance). Either way, OP has done an excellent job with directions on how to do this.

lake2k

I just cleaned my EGR tube and followed your instructions and you saved me hours and allot of money!!!

thanks

Eric

txsilverado1

Thanks! Another happy customer here. Just finished cleaning my EGR tube and throttle body. My car had a blocked tube at 116k. My theory is that cars that do city driving clog faster than cars that do mostly hwy. This is because it runs cleaner when at normal operating temperature and because there is less operation cycles for the system.

maximus_2

Did it solve the problem? Mine too is acting eratically.

Shifty Knob

Hello. I replaced my iac valve due to a stalling issue. The new iac valve fits but goes not have the little"cap" that is held on with the three screws. It has a place for the cap to sit over the hole but where the three screws should go in they are not tapped out. Is it necessary to tap the three small holes and fit the cap or will it work without it?

adroitcaptor

What does your post have to do with the thread topic?