Issues resolving P0401 Code

Old 01-29-2011, 10:10 PM
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Issues resolving P0401 Code

Hello fellow Acuraziners,

I have a 1999 Acura TL that currently has 249,000 miles on the odometer. I am having a slight issue with my vehicle that I am hoping someone will be able to assist me with. About a couple weeks ago I received the infamous EGR Insufficient Flow code, and I have been struggling to clear the code ever since. I cleaned the intake manifold ports throughly.. the manifold simply cannot get any cleaner! Would the EGR port on the lower intake cause this code to stay active? If so how can i go about cleaning this port? My thought is that you can't spray a whole can of carb cleaner into this port like you normally would with the manifold. Thoughts????
Old 01-31-2011, 03:58 AM
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"A code P0401 most likely means one or more of the following has happened:
  • The DPFE (differential pressure feedback EGR) sensor is faulty and needs to be replaced
  • There is a blockage in the EGR (tube), most likely carbon buildup
  • The EGR valve is faulty
  • The EGR valve may not be opening due to a lack of vaccuum"
http://www.obd-codes.com/p0401

intake manifold doesnt sound like the main cause in this case. im leaning towards carbon buildup, which is usually very effectively cleaned out using seafoam.
heres a diy thread on seafoam
https://acurazine.com/forums/9161152-post/

i cant guarantee it will solve the problem, but it's worth a shot

try googling P0401, look through forums, you might find your answer

hope this helps
Old 01-31-2011, 10:57 AM
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seafoam wont fix this
Did you remove the intake manifold from the engine and run carb cleaner and a wire rod thru the port,, and all the passages- clear thru to the egr valve ??

cant be done `on the car` correctly!

on egr valve: clean and lube the operating arm
remove valve from manifold and clean ports there too
Old 02-01-2011, 07:01 PM
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Originally Posted by 01tl4tl
seafoam wont fix this
Did you remove the intake manifold from the engine and run carb cleaner and a wire rod thru the port,, and all the passages- clear thru to the egr valve ??

cant be done `on the car` correctly!

on egr valve: clean and lube the operating arm
remove valve from manifold and clean ports there too
You are correct in that I did remove my intake manifold and ran carb cleaner through the port. I used my 8 mm drill bit (per the service bulletin) to clean the port thoroughly..even used a wire brush to work it all the way through. After the code was logged a second time, I pulled off the manifold again and literally soaked a whole bottle of carb cleaner through the hole and went through the same exercise. Furthermore, because I have 249k miles on the engine I decided to just go ahead and replace the EGR valve for good measure. What I neglected to do was run a wire through the port on the intake manifold... not sure if there is a hidden passage at the bottom that is clogged???? Also when changing the EGR valve itself, I inspected the port(s) that the value sits over. Perhaps there is a insufficient flow going from valve port over to the port on the lower section of the intake. If that is the case, how can I determine this? Not sure how to run a wire through that particular path, and wasn't sure if it was safe to soak the lower intake section with carb cleaner like we typically would do the upper intake manifold. Any suggestions? It appears as if with the amount of miles I have the typical method of cleaning the manifold isn't enough for clearing the P0401 code.

Thanks for the feedback.
Old 02-02-2011, 05:53 AM
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ck our diy on `thermoblock spacer install and EGR cleaning`

it shows how to do it right
You are missing the entire length of the passage thats clogged, and the valve end will look the same- cant do this job by cleaning just the `end` opening

You can remove the sensors and end plates- run carb cleaner (many use 3 cans)
and a Wire coat hanger or similar rod thru the passage and out the other end-
run cleaner thru the throat of tb, thru egr pathway, flip manifold throat down and spray everything again -flip back up and repeat final time
rinse the manifold with water, dry FULLY etc etc

the 8mm drilling was for acura to install a smooth sleeve in the bore so it didnt clog as fast,,about 40-50kmiles before then,,now 75k~ and needs cleaning

Until you push a rod thru from egr valve port to the port in manifold- you are not done and will keep getting codes and poor running
Old 02-02-2011, 07:23 PM
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Originally Posted by 01tl4tl
Until you push a rod thru from egr valve port to the port in manifold- you are not done and will keep getting codes and poor running
Thanks again for the feedback. After going back in again I found that the culprit wasn't within the manifold, but was actually the passageway in the car that goes from the EGR valve port over to the port in the the injector base (piece that the manifold rests on). From the surface, those ports are clean as a whistle on both ends. But running that rod through revealed a different story.

EGR port reference on item #12:

http://www.acuraautomotiveparts.org/...ystemcomp=List All&vinnoT=&trim=&trans=&view=normal

I guess I was confused because I didn't recall the DIY mentioning about servicing the port in the car. In the past I have only followed the instructions related to the manifold itself. I guess with the high mileage I have (especially given that I've never cleaned that particular port), it is to be expected.

Thanks again!
Old 02-03-2011, 03:09 PM
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So after discovering the EGR passage on the car was plugged through the cylinder head, we were able to clear everything out pretty good. Cleared the code, drove it around for an hour and checked the ECU to find no pending 0401code...yaayy!! This has by far been the most challenging EGR task ever done to date on this car.

01tl4tl.. being that my EGR passage was pretty bad through the lower intake, I was thinking that maybe I should jump on the Seafoaming bandwagon. No telling what 249,000 miles has done to my valves, pistons, etc.!! My question is in regards to the spark plugs. With just shy of 50,000 miles on them, I am not quite ready to swap them out yet. Will doing this seafoam require me to change out the plugs at this time? If so, perhaps I should wait for another 10-15k miles to do everything then. Thoughts??
Old 02-03-2011, 08:11 PM
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If concerned about it:
you can avoid any chance of loading up the plugs with crud by doing the gas tank method
1 can to 8 gallons- just under half a tank
do that twice and a shot thru the TB with some carb cleaner or deep creep and you are done

that will get everything the vac port will- in a slow gentle manner over a tank versus
blaster method which depends on a good afterdrive to blow the crud off the plugs

As a general question- its fine to do via master vac port with 50k on the plugs
its all in the burn off drive once you loosened crud

with high miles I would throw a new $3 oil filter on, add 1/2 can to oil and drive 150-200 miles,,up to 500 if you commiute a lot in a week
change oil and filter after 15 minute warmup drive
Thats going to remove years of sludge, put it in the filter- and ready to drain the rest by the oil pan plug--
!Important its warm 15 minutes freeway drive so crud is liquidfied

See www.seafoamsales.com there are a few pages of FAQs and methods to seafoam.
that 2000 rpm blast does an awesome job~
Old 02-03-2011, 08:18 PM
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we need to redo the egr cleaning DIY thats for sure!
Use shop vac to suck out whatever you can after poking wire in lower manifold
If it looks like carbon buildup- scrape it off!

seafoam wont help this problem
EGR = Exhaust Gas Recirculation= some exhaust gas is routed back into the manifold and cylinders for reburning..smog control, reduced power..
To my knowledge, seafoam wont be much use by the time it goes thru the exhaust process~
all we can do is manually clean it every 75kmiles for 00+ cars, or less for 99s, with only 1 port they clog faster
Why doesnt the repair manual or owner book call for this?--they didnt know a decade+ ago when the books were written and its never been updated--thats what azine is for!!
to help you find things techs on the street wont know
Old 02-03-2011, 08:51 PM
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thanks
Old 02-04-2011, 12:17 PM
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Originally Posted by 01tl4tl
If concerned about it:
you can avoid any chance of loading up the plugs with crud by doing the gas tank method
1 can to 8 gallons- just under half a tank
do that twice and a shot thru the TB with some carb cleaner or deep creep and you are done

that will get everything the vac port will- in a slow gentle manner over a tank versus
blaster method which depends on a good afterdrive to blow the crud off the plugs

As a general question- its fine to do via master vac port with 50k on the plugs
its all in the burn off drive once you loosened crud

with high miles I would throw a new $3 oil filter on, add 1/2 can to oil and drive 150-200 miles,,up to 500 if you commiute a lot in a week
change oil and filter after 15 minute warmup drive
Thats going to remove years of sludge, put it in the filter- and ready to drain the rest by the oil pan plug--
!Important its warm 15 minutes freeway drive so crud is liquidfied

See www.seafoamsales.com there are a few pages of FAQs and methods to seafoam.
that 2000 rpm blast does an awesome job~
Sounds good. I went ahead and purchased three 16 oz cans of Seafoam and one can of Seafoam spray this morning (couldn't find the Deep Creep version in the store). I was just under the halfway mark on the fuel, so I took one bottle to add to the existing fuel. In typing this I realized that I forgot to grab a cheap oil filter to capture the sludge. I will go back to grab one this afternoon. A few questions:

1. Can I swap oil filters without draining the oil? If so, should I expect to have a small puddle of oil to clean up once I loosen the filter? Also, should I swap out the filter while the engine is warm or should I wait a couple hours until it cools down?

2. In regards to the seafoam spray, how much should i spray inside the TB? Although I haven't yet read up on how to use the Deep Creep/Seafoam spray method, is it safe to assume that I would spray with the TB plate open so that everything will make its way to the intake upon putting the air tube back together and starting the engine?

Thanks again!
Old 02-04-2011, 12:24 PM
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Originally Posted by 01tl4tl
we need to redo the egr cleaning DIY thats for sure!
Use shop vac to suck out whatever you can after poking wire in lower manifold
If it looks like carbon buildup- scrape it off!

seafoam wont help this problem
EGR = Exhaust Gas Recirculation= some exhaust gas is routed back into the manifold and cylinders for reburning..smog control, reduced power..
To my knowledge, seafoam wont be much use by the time it goes thru the exhaust process~
all we can do is manually clean it every 75kmiles for 00+ cars, or less for 99s, with only 1 port they clog faster
Why doesnt the repair manual or owner book call for this?--they didnt know a decade+ ago when the books were written and its never been updated--thats what azine is for!!
to help you find things techs on the street wont know
I would imagine that for the average TL owner, there shouldn't be any EGR related problems via the lower manifold. Perhaps I am an exception due to the high mileage that I exhibit. I am excited about the Seafoaming effort, nonetheless. I used to think that I did not need it simply b/c the car always ran fine, and my gas mileage was always good (always use QT or Chevron 93 octane fuel). After this unusual EGR issue with this carbon, I have a totally different thought process now!
Old 02-04-2011, 06:29 PM
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what seafoam spray did you find? deep creep is the name of its aerosol version
Engine off- spray the air plate on both sides and edges- use right hand to open throttle at spring area to open plate (lube those too)
wipe up runoff!!- start engine- with tube removed to air filter,,will run bad as seafoam moves thru, use throttle control to keep running

I would do the air plate on seperate day, engine cold
then do warm up drive and use the Master vac port with the spray
do the blow out drive and let it cool off
Then do the TB air plate when its cold
You add seafoam as the engine will process it- no more than 50/50 dilution with the fuel or it stalls..you get a feel for it pretty quick,,but dont slam a bunch in at once

oil filter, turn wheel for better access from right side, many can fit under far enough without lifting the car up to reach the filter.
Get the filter broken loose- then slide a gallon size ziplock bag over it- slide all the way on to it.
spin filter off and the contents of filter are contained
A small amount of drip happens on car and maybe the ground
keep rag and carb cleaner handy!
Wipe the filter mating surface clean and be sure the old rubber sealing ring came off with the filter
buy 1 extra qt oil to replace whats lost in filter swap, so 6 qts total
Old 02-05-2011, 11:41 AM
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Originally Posted by 01tl4tl
what seafoam spray did you find? deep creep is the name of its aerosol version

http://www.seafoamsales.com/sea-foam-spray.html

I found the Sea Foam aerosol Spray product from Advance Auto Parts. Not sure what the difference between this product and the Deep Creep, as they are both made by the same manufacturer. Can I use this product to spray into the vac port the same way we would do with the Deep Creep? Or would you recommend me taking this product back and going for the Deep Creep instead?
Old 02-05-2011, 04:57 PM
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no its fine--
looks like they removed one ingredient- the stay behind lube possibly, so cars with super trick intakes could use it.
I have the 3 foot straw but not required on TL

Based on their website- go thru the TB throat, past air plate, and the master vac port as usual
Keep rpm 1500-2000 and half a can or so for one treatment
wait 10-15 minutes and do the afterdrive
repeat in a week or month for fullest effect then good for a year
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