DTC P1077 – Testing your Acura RSX IMRC

DTC P1077 – Testing your Acura RSX IMRC

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The Acura RSX IMRC is otherwise known as the Intake Manifold Runner Control. This control unit is very similar to the earlier DOHC Honda engines, like the B series. Much like the previous models, the IMRC is a valve that opens runners in the intake manifold. This allows for a low throttle and high throttle operation that increases intake velocity and low speed engine responsiveness.

The K20 engine found in the Acura RSX is remarkably responsive and has been hailed for it’s excellent range of torque at low engine speed. This is due to the way that i-VTEC works, as well as the Acura RSX IMRC. This unit opens the larger passages in the intake manifold above 4800 RPM. When this valve fails, becomes clogged or there’s a problem with your Acura RSX IMRC wiring, you’ll see your RSX check engine light turn on.

Acura RSX IMRC check engine lightWhen you see your Acura RSX check engine light turns on, you will need a OBDII scan tool to retrieve your stored trouble code.

Once you’ve pulled out the OBDII trouble code, it should read as a P1077 or a P1078. Other possible OBDII codes include P0661: IMT Circulation Voltage Low but our test vehicle is a P1077: IMT Valve Stuck Shut.

This OBDII trouble code translates to Intake Manifold Runner Control (IMRC) System Malfunction at high speed or low speed. Either way it’s a serious problem because your 2.0 liter DOHC K series engine isn’t running efficiently.

Today I’ll be showing you how to test the wiring of your Acura RSX IMRC valve in a 2003 model. This vehicle has the OBDII trouble code of P1077 stored in the engine computer, and we’ll begin testing the wires directly.

DTC P1077 - Testing your RSX IMRC

Of course when you are conducting this test, you will need to use a digital multimeter. If you are not sure on how to use this device, check out our guide here. To begin this testing, you will need to insert the RSX key and turn it to the “ON” position. This will allow you to read the power and ground signals at the Acura RSX IMRC valve.

DTC P1077 - Testing your RSX IMRC 2

When the P1077 or P1078 trouble code crops up, you’ll need to test the wiring. In order to do this you will need to open your hood and remove the intake manifold cover to expose the valve and wiring.

Begin by removing the two 10mm bolts that run through the top of the intake manifold cover. These hold the cover in place. Remove these bolts and set them to the side carefully.

DTC P1077 - Testing your RSX IMRC 3

Lift up on the intake manifold cover, and make sure to take care around the intake piping. There’s a pin that runs into the top of the intake pipe, so make sure to gently remove the cover.

DTC P1077 - Testing your RSX IMRC 4

Once you have the intake manifold cover removed to your i-VTEC 2.0 liter engine, you can now access the vacuum hose and wiring of the Acura RSX IMRC.

DTC P1077 - Testing your RSX IMRC 5

Begin testing the vacuum hose by removing the hose and checking for cracks or any signs of damage. Carefully lift up on the IMRC hose to remove from the runners and the plastic guides that hold it in place.

DTC P1077 - Testing your RSX IMRC 7

Once you have determined that the vacuum hose shown above is intact and okay, you can begin testing the Acura RSX IMRC wiring. Start by carefully unplugging the three pin harness. This harness is hard to access and there’s not much wiggle room as it’s secured to the alternator.

How does the Acura RSX IMRC fail?

This usually happens when you remove the Acura RSX intake manifold. Many people do this without knowing that the IMRC is still connected. This can cause damage to the signal wire, which again is run past the alternator. The heat generated by the RSX alternator can cause the wires to become brittle and break internally.

Other jobs that can cause your Acura RSX IMRC to fail include replacing your alternator or your RSX starter. Now that you have tested the vacuum hose to the IMRC, you can test the wiring.

Testing your Acura RSX IMRC wiring

Make sure that your RSX ignition is turned to the ON position. Unplug the IMRC connector, and refer to the RSX IMRC wiring diagram below.

DTC P1077 - Testing your RSX IMRC 6

Testing the wiring connector is easy, and should begin with PIN 3. With the RSX ignition turned to the ON position, you should have 5 volts of switched power here. If you have a power signal, move onto the ground signal. This is PIN 1 and should be tested by putting the red lead of your multimeter to the positive battery terminal, and probing PIN 1 with the black lead.

If you read 12 volts here, you have a ground signal and your Acura RSX IMRC should have everything it needs to operate. The last thing to check is the signal wire, which runs to your engine computer.

Before you do that however, you should test the IMRC valve directly. To do so check out our guide on how to measure the internal resistance of your Acura RSX IMRC valve. Make sure to check this link before you continue to testing the valve wiring to your engine computer.

Have any questions about our Acura RSX IMRC testing guide? Leave them for us below and let us know!

10 COMMENTS

  1. Hi Pro Street, I had the P1077 trouble code in my RSX after I replaced my starter. When I took off the intake manifold i didn’t disconnect the IMRC valve. After my RSX starter replacement the P1077 check engine light turned on. Please help

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