Engine Performance problem
1999 Honda Accord 4 cyl Front Wheel Drive Automatic 250K miles
I have been chasing down a P1941(?) EGR code issue. Have replaced cap, plugs, wires, egr- Have removed and cleaned Throttle Body and replaced gasket. Cleaned EGR port under EGR valve with carb cleaner and a piece of coat hanger. Removed uper intake manifold and cleaned the port that comes in right by the throttle body. I'm still getting P1941 and think I must have missed another port that is clogged. Does anyone have a detailed diagram they could email me so I dont have to drive 45 minutes to the dealer?
I am not able to find any reference to the code P1941. Can you please reconfirm the code.
March, 19, 2010 AT 9:12 AM
Check engine light is on. Code P1491 (?) Have done the following: 1) New cap, plugs, wires, rotor, EGR valve.
2) Cleaned runner from EGR base to upper intake with carb cleaner and coat hanger
3)Removed upper intake and cleaned the EGR port out on the LOWER intake manifold - Did not clean the upper but realize now I should have and plan to do tonight.
4)Honda mechanic friend said there is a plate underneath the fuel rail that has three holes that get clogged and should be cleaned- Do you know what he is referring to as all I can see are the fuel injectors. Do you have a diagram by chance?
March, 19, 2010 AT 11:12 AM
I have sent the diagnostics procedures to your email.
I have also added the TSB for you but seems they only apply to 6 cylinder engines
February, 3, 2011 AT 1:08 AM
I'm having the same problem would you please send me the diagnostic procedures as well?
February, 3, 2011 AT 3:58 AM
Can I have more information on your vehicle?
February, 3, 2011 AT 4:30 AM
Just noted you had posted another question on the problem so here are the repair porocedures taken from the TSB.
1. Remove the throttle body cover, intake manifold covers, ignition wire holder, and ignition wire cover. See Fig. 1.
2. Disconnect the brake booster vacuum hose and the vacuum hose from the intake manifold.
3. Remove the throttle body from the intake manifold (two nuts and two bolts). Leave all hoses, cables, and electrical connectors connected to the throttle body. Discard the throttle body gasket. See Fig. 2.
4. Remove the PCV valve from the cylinder head cover. Remove the intake manifold (three nuts and six bolts).
5. Remove the intake manifold chamber, IAT sensor, boost plate, and PCV hose from the intake manifold. See Fig. 3.
6. Cover the six ports on the bottom of the manifold with duct tape. See Fig. 4.
7. Use an 8-mm drill bit and carburetor cleaner to clean the EGR port in the intake manifold. Turn the drill bit only by hand. Do not use a power drill.
8. Put the special drill bit from the EGR pipe installation kit in your power drill. Coat the drill bit completely with clean engine oil.
NOTE: The oil coating is critical to drilling the hole accurately, and it contributes to drill bit life.
9. Insert the guide part of the drill bit into the EGR port. Make sure it is inserted fully. Then drill out the EGR port using steady pressure on the drill. Make sure the port is drilled through completely. See Fig. 5.
10. Clean up the aluminum chips from drilling, then remove the duct tape.
11. Put the manifold in a parts washer (solvent or soap and water) and clean it thoroughly. See Fig. 6.
Flush out the EGR port for 20 seconds.
Flush out the manifold from the throttle body opening. Run cleaner down each side for 20 seconds.
Flush each intake runner for 10 seconds. Start at the throttle body end and work towards the back.
Turn the manifold so the throttle body opening is facing down. Flush each main runner for 20 seconds.
Dry the manifold with compressed air and clean shop towels.
12. Place the EGR pipe from the kit into the EGR port. See
13. Use the installation tool and a small hammer to drive the EGR pipe into the port until it is flush with the port. Make sure the pipe will not contact the gasket after installation. See Fig. 8.
14. Install the intake manifold chamber; torque the nuts and bolts to 12 N.M (8.7 lb-ft). Install the IAT sensor; torque it to 18 N.M (13 lb-ft). Install the boost plate; torque the bolts to 12 N.M (8.7 lb-ft). Install the PCV hose.
15. Inspect the EGR port in the front of the injector base on the engine. If it is partially or fully clogged, clean the port.
16. Disconnect the 6P connector from the EGR valve. Remove the EGR valve. See Fig. 9.
17. Install the new EGR valve with a new gasket. Torque the mounting nuts to 22 N.M (16 lb-ft). Reconnect the 6P connector.
18. Install the intake manifold with the original gasket. Torque the mounting nuts and bolts to 22 N.M (16 lb-ft) sequentially in two or three steps. Route the PCV hose so it is not pinched under the intake manifold. See Fig. 10.
19. Install the PCV valve in the cylinder head cover.
20. Install the throttle body with a new gasket. Torque the mounting nuts and bolts to 22 N.M (16 lb-ft).
21. Reinstall the brake booster vacuum hose, vacuum hose, ignition wire holder, and all of the covers.
22. Connect the PGM Tester (loaded with SN200 or later software). Clear any DTCs.
23. Use the PGM Tester to override two-trip error detection.
From the PGM tester menu, select 1. Honda Systems.
Then select 2. SCS.
24. Test-drive the vehicle to make sure no new DTCs are set.