bobinyelm

New here so thanks for any help anyone can offer!

Just recently (500mi ago)bought a '98 from a longtime family friend that had recently had a new EGR valve installed after ERG related MIL.

Since purchase, we've been getting the dreaded P0401 Low EGR Flow MIL more and more often until it's become almost daily.

I've searched here and almost everywhere, and understand that the EGR piping or intake passages are probably obstructed.

I removed the EGR and confirmed that it is brand new, and suction opens a very clean pindle all the way. Looks good as it should with under 1000mi on it.

The passages below the EGR are spiffy clean, so I would guess the block is far down the tube, or in the intake manifold itself?

I was tempted to remove the approx. 8" long EGR tube from the EGR base to the intake manifold (4-10mm headed fasteners), but it's REALLY tight up against the firewall, and I was afraid I'd drop/lose either the nuts on the intake side, or the bolts on the EGR end, so wanted to make SURE it's worth cramming my hand back there, and that I could get a wire or a drill bit into the intake and make a REAL difference.

Other Web searches said that some RLs and TLs had an extended warranty on this, while others said the intake manifold needs to be removed, and that dealers get $700 to clean the port (no way can I justify this), and that it re-clogs every 40,000mi or so after that.

I am a pretty good wrench, but want to make sure I do it RIGHT the first time w/ minimum false starts.

Suggestions? Links to articles? Parts kits? Anything...please?

Thanks,
Bob

speedyd718

i've been battling this recently and took the pipe off my 99 yesterday. it wasn't as bad as it seemed. it is tight but i'm on 5'4" so i go back there relatively easy. the pipe was pretty clogged and i spray oven cleaner in it to clean it. the passage in the intake manifold was the pits (based on feeling it with my finger), but i'm not going as far as to take the manifold off to clean. i don't have that kind of time. i'm not sure if the cleaning did the trick. i don't drive too often on the freeway to get the car up to speed to test operation (roughly: the car must be warm, and you take the car up to 60-65mph then take your foot of the gas and let the car coast for 5-10sec). this is when the egr system is at full operation and when the pcm will sense for flow.

bobinyelm

Being over 6ft w/ hands that require "ExLrg" gloves makes it look and feel worse than perhaps it is. I need to find someone smaller with equally "educated" hands to work by feel (my wife kindly volunteered, but she is unpracticed with fasteners).

I read elsewhere that with the pipe off, you can use a twist drill between your fingers to rout out the gunk.

I suspect that MOST of the blockage is probably in the intake manifold itself, but I don't know that for sure.

Please keep me advised if your pipe cleaning did the trick.

I was hoping more people would have info on this since I cannot believe we two are the only ones experiencing this problem on the RL. I know it is VERY common w/ the TLs.

Bob

bobinyelm

I located the Acura drive sequence to set/unset the code if there is a malfunction.

Warm completely.
Drive between 25 and 55mph for 5 min or more.
Drive 55-75mph for a min of 5 seconds
Decelerate with fully closed throttle for 4 seconds or more.

It takes TWO drive cycles to set the MIL
The MIL will clear automatically if malfunction does not recur in 3 consecutive drive cycles.

speedyd718

i've tried a few times and i haven't gotten the mil to come on again. so, so far good. i'd go ahead and clean the pipe out. the dealer told me that, that's what they'd do (for $350, ha!). but that's why i gave it a shot.

if your wife will help it'll definitely help. the bolts and nuts are 10mm. i used a ratcheting wrench on the egr side (two bolts). i took off the egr valve itself to make it easier (12mm nuts).

and used a 1/4" drive ratchet with 10mm deep well socket on the manifold side (two nuts). it was easiest to climb on top to the motor to get to the manifold side nuts. you can see the pipe and the studs, it's not as covered as the write-ups i read made it seem. a short pipe will help to give you a little more leverage (i didn't use one though). only thing i moved out of the way was the brake boost hose.

bobinyelm

Yeah, I had my EGR off to estimate the hassle, and the only thing that gave me pause were my big paws (Sorry, couldn't resist the pun.). If that mass of vacuum tubes and hoses weren't right over the tube, it would be easy.

I don't think I'll trust my wife because while her hands are small, she doesn't have a "feel" for such things, though I know she'd give it a go.

Glad it worked out well for you. I thought for $350 they'd at least try running something up into the intake manifold passage.

Bob

acurob

I have a 96 RL and have a P0401 code as well. I put a new EGR valve on it and cleaned the EGR tube and the ports on the rear of the manifold. I also blew the air hose through the pcv tube and it flowed niucley out the rear of the engine. It still threw the code after a trif on about 30 miles on the freeway. Does anyone have na idea what I can do next to get it to stop throwing the code? Please help ideas welcome.

bobinyelm

When you say "cleaned the tube and the ports on the rear of the manifold," are you saying you removed the tube and made sure it was unobstructed, and that you cleaned the passage from where the tube connects into the intake manifold? If so, did you ream the carbon from the manifold passage with a twist drill (between your fingers or equivalent) so that you were sure the flow was pretty much unrestricted?

I think that's what you said you accomplished, and checked by pressurizing the intake manifold and noting a free flow of air out of the EGR valve base?

Just trying to establish exactly what you did.

acurob

Yes I cleaned the tube out and reamed the rear holes where the tube attaches to the rear of the manifold. I used a small pick and scraped it out. still threw the code


Just trying to establish exactly what you did.[/quote]

acurob

I didnt check for the free flow of air out of the egr base, just the manifold where the tube attaches

bobinyelm

But, if you cleaned and blew through the tube before replacing it, I am sure it came out of the EGR mounting base.

I pushed a 3/8" gas hose onto my air line and pushed it down into the base on the EGR side (so it sealed in the recess of the base), and with the throttle open, blew air into the base, and I could hear it rushing out of the throttle body (after chemically cleaning the tube/passage), but I haven't mechanically cleaned as you have yet (my hand is too big to work between the firewall and the intake manifold so I am waiting until a small-handed friend stops by).

But even after a chemical cleaning (carb cleaner, FI cleaner, brake cleaner), it's not throwing a code yet after several drive-cycles, though I know the passages are not completely open.

If your EGR valve were not opening, you'd be getting a different code w/ P0401 as well, I think. So I would imagine your ERG is getting the signal and is opening. I was thinking of verifying this w/ mine by putting a "T" in the vacuum line and running it out of the eng compartment to a small vacuum gauge held under a wiper blade so I could see it while driving to verify the EGR is getting good vacuum when it's supposed to open.

I want to get them WIDE open, or I know they will just plug again soon.

acurob

I think im going to tackle taking the manifold off and thoroughly cleaning all passages. This I know will take car of it. What a pain but I got to do it.

bobinyelm

Boy, I would think if blowing into the intake manifold flowed a lot of air up and out of the ERG base, that should do it.

Just before throwing the P0401 code, I am sure your passages were far more clogged than they now are, and yet you had no code.

Please keep us informed of how much of a hassle pulling the manifold was (like how long it took you, etc.), and how it worked out!!

I suspect I'll be right behind you.

Thanks,
Bob

speedyd718

well just to throw my 2cent in. did you use a oem egr valva as your replacement? i ask because most threads say that the valve itself is usually ok to reuse. so did you replace the oem with an aftermarket? if so try putting the oem back on. just a thought i had.

also my code has not returned since cleaning the pipe and clearing the manifold passage (manifold on).

also while i'm typing this take your car to the dealer the 96's (all honda's i believe) were involved in a technical service bulletin because of the emission systems on them. i'd see what they could do for you before you tackle the manifold.

speedyd718

here's is the link to the service bulletin acurob. the extension covers 14yr/150,000mi. hope you're in there.

replace the *=a

http://www.*cur*world.com/tsb/1998/b98-031.pdf

acurob

Ok, so I tried something different. So far no code after three good freeway trips. So here is what I did. I took the pcv valve off the end of the hose and attached my air compressor to it. I injected carb cleaner in the manifold with the compressor while the car was not running. After two injections I started the car and it blew a bunch of smoke out of the exhaust pipe. It ran like crap for a few seconds and smoothed out. It is running great and so for no code. Fingers crossed that I dont have to do the manifold but if I gotta I will. Just trying a few tricks before I tackle the job.

samlbc

Hi everyone. New guy here. i seafoamed my 99 RL and it helped a whole lot. I was getting the P0401 code and was getting horrible gas mileage. Im descent now but want better so im going to clean the EGR valve and Pipe one of these weekends. But strongly recommend sea foam. Worked better than expected.

bobinyelm

I poured a mixture of transmission fluid and Chemtronics B-12 cleaner down the EGR pipe to the intake manifold (maybe 2 ounces) and let it sit 24 hours (it should soften and dissolve the deposits), then held the throttle wide open and blew compressed air down the pipe until I could hear the air exiting the air cleaner (meaning the pipe/manifold passage was open) indicating the clog was opened somewhat.

Started the car (hold throttle 1/2 open until it fires-it WILL smoke for 20 seconds or so) and almost 1 month later NO MIL or P0401 whereas before it would set almost every trip.

That "fix" was from a very respected factory-trained BMW technician, BTW.

Since our car is a '98, no extended warranty, unfortunately.

tvgaman

samlbc, can you show me how did you seafoamed your 99RL? i have a 00RL and of course the P0401 won't go away. i had someone replaced the EGR last month but P0401 came right back. thanks,

bobinyelm

An update-

Using SeaFoam, or other cleaners is a temporary stop-gap measure. It works for a while, but it's unlikely it will open the passages enough to stay open for TOO long (read my comments as to how long it will likely work).

I finally broke down and removed the EGR pipe (the bent one between the base of the EGR valve and the manifold).

Then, using metal bottle brushes bought at Harbor Freight (they look like large gun cleaning brushes with 8" long extended twisted wire "handles") ran them into the port in the manifold while generously spraying carb cleaner in w/ the brush.

I cut the loops off the ends of the extensions and hooked them in to a drill chuck (at slow speed) and used my other hand to direct the extension of the brushes (so they didn't kink) as they went into the port.

I think I went in 4" or so.

LOTS of carbon and crap came out with the brushes each time they were withdrawn, and finally they came out pretty clean and I could feel they had "broken through" the carbon/sludge " dam.

We put another 10,000mi on the RL w/ no further EGR LOW FLOW MILs before we sold it.

The entire operation took about 45 minutes.

That was the END of the problem for probably the next 100,000 mi.

Removing the intake manifold is the NICE way of doing it, but it will take FAR longer, and open you to far more hassles with regard to labor, dropped bolts/hardware, and possibly gasket leaks and such.

With my method, you only need to remove the EGR tube (and the EGR valve to give you room to work behind the engine).

Just get a couple of the gaskets in advance for the tube ends as a precaution. I had one bend so I replaced it.

Bob

3.5RLv-tec?

iTrader: (2)

Hi, my P0401 light just came on yesterday; i cleaned it last year. I cleaned the egr valve, egr pipe, and the hole where the egr pipe connected today, but the CEL still came back on like 20 miles. I just wondering can you replace the EGR valve with an aftermarket one? I don't want to wait because my local Auto has one. I've planned to clean the hole again; spray ton of carb cleaner and let it sit there over night before I get a new EGR valve. Any idea?

bobinyelm

Remember, the P0401 is rarely if ever due to the EGR valve-it's low flow through the passages in the manifold itself.

The ONLY thing that worked long term for me was using wire brushes (they look like gun bore cleaning brushes) and running them in through the port in the manifold after removing the crooked pipe that leads up to the EGR valve.

As I posted, it took insertion about 4" before we hit the "hard-clog" that the brush broke through and fully opened the port.

Replacing the EGR valve's normally a waste of money.

3.5RLv-tec?

iTrader: (2)

Yeah, thats what I plan to do this weekend before spending money on a new EGR valve. Last year I cleaned by spraying ton of carb cleaner into the hole and just use a drill bit. I did the same thing today and the light came back on like 20 miles, I like WTF. Where did you get the gun bore like brushes? I went to autozone and pepboys and all they have it metal brushes, the one look like to clean car wheel. They had a round one but it was to big for the hole.

3.5RLv-tec?

iTrader: (2)

Is this the thing you use? Or similar to this?
http://www.walmart.com/ip/Hoppe-s-0....-Pack/27735822

bobinyelm

As I mentioned up the thread, Harbor Freight sells a set of bore brushes that are perfect for $6.99.

Illustration: http://screencast.com/t/jBt2YBY6t30S

http://www.harborfreight.com/10-piec...kit-95947.html

Just cut off the loop at the end of the twisted wire handle, and check the brush up in a variable speed drill and while guiding it w/ your one hand (so it won't bend into a kink) push the slowly rotating brush into the ERR bore as far as you can.

Do be careful that the wire handle doesn't break, leaving part of the brush in there, but I was reasonbly rough w/ mine and it didn't break.

I sprayed carb cleaner in there as I fed the brush in hoping to soften up the crud up a bit.

Lots of disgusting sludge, carbon, and gunk came out of the bore every time the brush was withdrawn.

The actual cleaning takes 5 minutes max. The rest is removing and replacing the EGR and bent tube.

3.5RLv-tec?

iTrader: (2)

Thank you so much for providing the link. I need to get that and start working on it. I need to go for an emission test. Now I need to get back on my essay lol.

bobinyelm

NOTE TYPO IN MY POSTING:
"Just cut off the loop at the end of the twisted wire handle, and check the brush up in a variable speed drill and while guiding it w/ your one hand (so it won't bend into a kink) push the slowly rotating brush into the ERR bore as far as you can."

I MEANT "CHUCK" it up in a low speed drill.

Let us know how it works for you please!

Bob

3.5RLv-tec?

iTrader: (2)

Will do. I have been so busy with school and work, so I haven't started on it yet. Hopefully I will have some free time this weekend to do it.

RL98

http://accuratecars.com/blog/2008/11...he-first-time/

Had Accurate Cars clean mine at 165k miles and the P0401 has not recurred. I did have a P1491(EGR insufficient lift detected) at 180k and cleared it - has not recurred.

98 RL 212k miles

holyabish1

I personally would never do this on a C35 engine, ever. Since we have vacuum controlled flaps inside of the intake manifold itself. Seafoam is also a terrible idea, unless you have a low mileage vehicle. Get a piece of that hard debris between one of those flaps, and could bend it, or worse, break a piece off. BMW tech might think it is good, but the C35 is a completely different beast from any BMW motor.


EGR issues have also been related to detonation, and detonation may lead to head gasket issues. Anyone running a MIL for the EGR should just repair asap. This includes removing the intake and giving the lower plenum a good cleaning.

Just my two cents

holyabish1

Is there no edit function on posts? Man, I'm a terrible writer, lol, this means I have to read over things more carefully, lol.

Would like to add. I'm adding an oil catch can (yeah a little ricerish) to prevent access oil from being deposited into the intake. My theory is, that it'll help suppress the amount of oil in the intake, therefor limiting the amount of burned oil deposits in the egr.


Would also like to add, the EGR on this car is nothing to take lightly . Don't look for a "quick fix", pay once, cry once. Seafoam and other cleaning items is not the way to go. Take off the EGR, clean it, while you're at it, clean the intake.

Just be careful not to bust your knock sensors, haha. It's a simple job really, and IMO, give a better piece of mind, than putting crazy additives in any hole.