ScottD

2002 Honda Civic EX, P0304 code – misfire on cylinder 4. Changed plugs and cylinder 4 coil. That did not fix the problem. Dealer diagnosed as bad EGR valve and EGR ports clogged. Quoted $300 to repair plus $272.00 for EGR valve. I replaced the EGR valve myself. That did not fix the problem. I then cleaned the EGR ports. That did fix the problem. Runs like new now. I Had a very hard time finding information on how to clean the EGR ports, so I’m posting the steps here. Sorry, I didn't take any pictures. You'll need a Haynes or other repair manual for the details and pictures. These are general, high-level steps.

1. Relieve fuel pressure. (See Haynes or other repair manual.)
2. Disconnect negative battery cable.
3. Remove the air resonator and air filter housing.
4. Jack up the front of the car. One of the intake manifold bolts is accessed from under the car. Also, the oil filter is in the way and must be removed. So you might as well drain and change the oil too.
5. Drain coolant from radiator.
6. Disconnect throttle and cruise control cables from the throttle body. (See Haynes or other repair manual.)
7. Mark hoses and disconnect them from the intake manifold and throttle body. I used different color finger nail polish to mark the hoses.
8. Disconnect all electrical connections from throttle body, intake manifold and fuel injectors.
9. Remove the bolts holding the intake manifold in place – two at top center, two at the bottom ends, and one at bottom center (12m accessed from under the car). I used a 12m closed end wrench and a piece of copper pipe as an extension.
10. The intake manifold (including throttle body, injector base and fuel rail) can now be removed. Move the intake manifold toward back of car off the three studs and lift it up.
11. The EGR passage ways are now exposed behind the injector base. The ports into the cylinders are exposed as well on the back side of the engine head. Clean the ports and passage ways with a screw driver, rags and carburetor cleaner. Use a shop vac to prevent carbon buildup from falling into the cylinders. Three of my EGR passages were blocked with carbon gunk. Surprisingly, the port that wasn't blocked was the one that was misfiring - cylinder 4.
12. Replace the intake manifold gasket with a new one and reassemble.

EGR valve probably did not need to be replaced. Just cleaning the EGR valve and EGR ports probably would have fixed the problem. Spent $100 for dealer diagnostics, $100 for plugs and coil, and $172 for EGR valve. Saved about $400 on EGR port cleaning and dealer markup on parts by doing it myself .

gearbox

iTrader: (95)

wow thats a ton of work! at least problem solved. moving to 7thgen diy section.

kemcolleen

We have followed all the above step til #10, the manifold will not budge. was this hard to remove? Any help would be appreciated

kemcolleen

We have followed all the above step til #10, the manifold will not budge. was this hard to remove? Any help would be appreciated

ezone

I'd guess you haven't found all of the fasteners yet.

Do you have ALL of the hardware removed, including the supports on the bottom of the intake that are accessed from underneath the car?

The gaskets can make everything stick just a little. Usually only needs a POP to get the manifold loose after all the bolts are removed.

fsckewe

Did you unbolt the two mounting brackets? #31 in the image posted(3 bolts in total).

I did this on a 2003 a few weeks ago. You need to unbolt 5 'things' on the manifold, and you don't need to do anything from underneath except the brackets noted above.

Remove the two long nuts (#18) on the top of the manifold and two bolts on the way outsides, #33.

The 5th (can't recall if it is a nut or bolt) can be accessed from the top after removing #5 and #15.

The manifold and injector base will come out together.

ezone

Hey, I'm glad you popped in here.
I was looking for that longazz thread to link here.

https://www.civicforums.com/forums/3...ml#post4582097

fsckewe

Thought I could give a little back after our epic exchange.

LeeM

Thanks to ScottD for the original cleaning post. A few more notes from my 15 hour cleaning project on a 2004 California emissions Civic.


Depressurizing fuel injectors is not necessary:
On my 2004 Civic engine, I removed the spark coil cover (quarter turn screws), loosen but do not remove spark coil connectors as needed, remove the air cleaner support bracket (2 10mm wrench size nuts), unplug the 4 injector connectors. At the mechanic's right, find a rubber tube from the injector fuel return rail to the evaporative cannister purge valve and disconnect it. Remove two 10mm wrench size hex nuts holding injector fuel rail to the engine. Rock and lift injector fuel rail and four injectors up and clear. Use a wire to hang injector rail from the inside of the hood. Don't bump or touch the injectors. Clean injector o-rings and install them with a coating of clean engine oil.


Assemble intake manifold and injector plate on the workbench:
Put the intake manifold and injector plate together on the workbench. There are two or three 12 mm wrench size hex nuts that hold the parts together. It is much easier to get these fasteners finger tight on a workbench rather than struggling in the tight spaces of the engine compartment later.


There about 8 nuts and bolts holding the injector plate and the intake manifold to the engine. You need 12 mm combination wrench for most of these fasteners. Usually Honda specifies really high-torque levels for their fasteners. I am buying some long pattern combination wrenches so I can develop more torque when tightening engine fasteners. The wrenches are mostly special order so I used the internet and bought a 9 piece set from Sears for $58.44.


Magnetic nut holder:
I made a magnetic nut holder using a broken piece of 5/8%u201D diameter neodymium magnet holding the nut in the wrench head. By matching the starting thread on the engine bolt with the starting thread of the attachment nut, you can get the nut started. Then spin the nut down with a wood chopstick or screwdriver or finger tip.

Match your original intake manifold gasket at the parts store:
There are two different intake manifold gaskets for the Honda Civic and beware both gaskets fit the D17A1 engine.


Year Engine Napa number
2004 D17A1 NAPA MS96390-1 Has gas hole in corner
2000-2003 D17A1 NAPA MS96390 No gas hole.


Supplies you will need:
Two cans of spray type carburetor and egr valve cleaner.
New oil filter.
Medium strength thread lock for fasteners you can't pull to specified torque.

Tomclancy

Is this the same steps for a 2000 civic dx? becuz i been having an idle issue with it idle normal for bout 5 mins, then drops and comes back up. Could the ports be clogged?

fsckewe

These instructions are for a 7th generation civic, model years 2001-2005 and the D17Ax engines.

For your 2000, it is a 6th gen civic and the DX has a D16Y7. I'd guess the procedure differs from the one listed here.

At any rate, no telling if this is your problem. Search for surging idle and see if that is any help.

ezone

EGR will not cause that. You can prove it by disabling the EGR valve and see if it still happens.

Tomclancy

Thanks will search that. Didnt know what else to look up.

And ty ezone ill try that also. Idk how to quote more then one person on here to reply to lol.