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I just removed the intake manifold RL to clean the muck out, I also cleaned the EGR Valve that caused insufficient EGR flow, now the code is gone and I've driven over 300 miles no new codes y 98 Acura RL. Problem is the mentainanca required light will not reset now ....Any sugestions?? .....THANKS GUYS!!
You have to reset it. with the ignition off, push and hold the select/reset buttond on you dash.
keep holding and turn the ignition to the on possition, keep hold untill the light shuts off
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Install a tachometer on the engine, following the manufacturer's instructions.
Detach the engine wiring harness connector from the Idle Air Control (IAC) solenoid.
Disconnect and plug the vacuum supply hose from the EGR valve.
Start the engine, then apply the parking brake, block the rear wheels and position the transmission in Neutral.
Observe and note the idle speed.
If the engine will not idle with the IAC solenoid disconnected, provide an air bypass to the engine by slightly opening the throttle plate or by creating an intake vacuum leak. Do not allow the idle speed to exceed typical idle rpm. Using a hand-held vacuum pump, slowly apply 5-10 in. Hg (17-34 kPa) of vacuum to the EGR valve nipple.
If the idle speed drops more than 100 rpm with the vacuum applied and returns to normal after the vacuum is removed, the EGR valve is OK.
If the idle speed does not drop more than 100 rpm with the vacuum applied and return to normal after the vacuum is removed, inspect the EGR valve for a blockage; clean it if a blockage is found. Replace the EGR valve if no blockage is found, or if cleaning the valve does not remedy the malfunction.
Fig.: ... remove the valve from the intake manifold
Fig.: Thoroughly clean the mating surfaces of the manifold and the EGR valve (if being reused)
Disconnect the negative battery cable.
Remove the vacuum hose from the EGR valve.
Using a 22mm wrench or crowfoot, disconnect the EGR valve-to-exhaust manifold tube from the EGR valve.
Remove the EGR valve mounting fasteners, then separate the valve from the intake manifold.
Remove and discard the old EGR valve gasket, and clean the gasket mating surfaces on the valve and the intake manifold.
To install:
Install the EGR valve, along with a new gasket, on the upper intake manifold, then install and tighten the mounting bolts to 15-22 ft. lbs. (20-30 Nm).
Connect the EGR valve-to-exhaust manifold tube to the valve, then tighten the tube nut to 26-47 ft. lbs. (35-65 Nm).
Connect the vacuum hose to the EGR valve.
Connect the negative battery cable.
3.0L OHC (4 valve)
Fig. : EGR mounting-3.0L OHC (4 valve) engine
Disconnect the negative battery cable.
Remove the vacuum hose from the EGR valve.
Remove the two EGR tube-to-EGR valve retaining nuts.
Remove the EGR valve mounting fasteners, then separate the valve from the intake manifold.
Remove and discard the old EGR valve gasket, and clean the gasket mating surfaces on the valve and the intake manifold.
To install:
Install the EGR valve, along with a new gasket, on the upper intake manifold, then install and tighten the mounting bolts to 15-22 ft. lbs. (20-30 Nm).
Connect the EGR valve-to-EGR tube, then tighten the retaining nuts.
Code P1491 in Honda/Acura vehicles means insufficient EGR valve lift. Note - this is not the same as 0401 for EGR low flow when you have to clean EGR passage in the intake manifold. If code 1491 is not accompanied with 0401 - that could be faulty EGR valve itself. Try to reset the code, and if it will return soon - replace EGR valve. If, however you see both codes together - cleane the manifold passage before you replacing the valve.
REMOVE EGR VALVE CLEAN OUT THE CARBON INSIDE THE EGR VALVE PORT HOLE IN THE INTAKE MANIFOLD WHERE EGR VALVE SITS.CAREFULLY USE A PIECE OF CLOTHES RACK OR A TINY SCREW DRIVER CLEAN CARBON OUT ROUND HOLE.USE A SHOP VAC TO VACUUM UP THE DEBRIS TO KEEP FROM GETTING INSIDE INTAKE.DONT USE SHOP VAC IF YOU HAVE ANY FUEL LEAKS OR SMELL GAS FUMES UNDER THE HOOD.
Install a tachometer on the engine, following the manufacturer's
instructions.
Detach the engine wiring harness connector from the Idle Air
Control (IAC) solenoid.
Disconnect and plug the vacuum supply hose from the EGR valve.
Start the engine, then apply the parking brake, block the rear
wheels and position the transmission in Neutral.
Observe and note the idle speed.
If the engine will not idle with the IAC solenoid disconnected,
provide an air bypass to the engine by slightly opening the throttle
plate or by creating an intake vacuum leak. Do not allow the idle speed
to exceed typical idle rpm. Using a hand-held vacuum pump, slowly apply 5-10 in. Hg (17-34
kPa) of vacuum to the EGR valve nipple.
If the idle speed drops more than 100 rpm with the vacuum applied
and returns to normal after the vacuum is removed, the EGR valve is OK.
If the idle speed does not drop more than 100 rpm with the vacuum
applied and return to normal after the vacuum is removed, inspect the
EGR valve for a blockage; clean it if a blockage is found. Replace the
EGR valve if no blockage is found, or if cleaning the valve does not
remedy the malfunction.
Fig.: ... remove the valve from the intake manifold
Fig.: Thoroughly clean the mating surfaces of the manifold
and the EGR valve (if being reused)
Disconnect the negative battery cable.
Remove the vacuum hose from the EGR valve.
Using a 22mm wrench or crowfoot, disconnect the EGR
valve-to-exhaust manifold tube from the EGR valve.
Remove the EGR valve mounting fasteners, then separate the valve
from the intake manifold.
Remove and discard the old EGR valve gasket, and clean the gasket
mating surfaces on the valve and the intake manifold.
To install:
Install the EGR valve, along with a new gasket, on the upper
intake manifold, then install and tighten the mounting bolts to 15-22
ft. lbs. (20-30 Nm).
Connect the EGR valve-to-exhaust manifold tube to the valve, then
tighten the tube nut to 26-47 ft. lbs. (35-65 Nm).
Connect the vacuum hose to the EGR valve.
Connect the negative battery cable.
3.0L OHC (4 valve)
Fig. : EGR mounting-3.0L OHC (4 valve) engine
Disconnect the negative battery cable.
Remove the vacuum hose from the EGR valve.
Remove the two EGR tube-to-EGR valve retaining nuts.
Remove the EGR valve mounting fasteners, then separate the valve
from the intake manifold.
Remove and discard the old EGR valve gasket, and clean the gasket
mating surfaces on the valve and the intake manifold.
To install:
Install the EGR valve, along with a new gasket, on the upper
intake manifold, then install and tighten the mounting bolts to 15-22
ft. lbs. (20-30 Nm).
Connect the EGR valve-to-EGR tube, then tighten the retaining
nuts.
P0401: Isufficient Flow Detected in EGR system.
-clean the EGR port with the carburetor cleaner.
-clean the EGR passage inside the EGR valve with the caburetor cleaner.
Reset the light, if the light still coming back, then replace the EGR valve.
I am fixing to change my EGR valve and the piece of paper that came with the part say this:
Important Notice
Before installing this part, check the EGR valve passage in the intake manifold and clear any carbon blockage. Failure to do so will result in repeat malfuntion of the EGR valve system. Refer to a technical service manual or contact a service dealer for proper cleaning procedures.
You need to pull your plenum and more than likely the intake and clean out the vaccum port in the intake where the egr pipe connects to the back of the intake.Not sure if you can do it with just pulling the plennum or not though.Having the same prob with my 96 rl.Keeps kicking the insufficient flow to egr valve code at about 30 miles.
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