Code P1078- Intake Manifold Runner control

JJBURTON5

MEMBER
2004 ACURA RSX
2.0L
4 CYL
2WD
AUTOMATIC
141,000 MILES

Hello again, recently my RSX has had the engine light illuminating. After using a diagnostic, I have discovered that it has stored the diagnostic code P1078.
I have tested the wiring on the IMRC except for internal resistance (Due to the awkward position of the sensor). I have visually inspected the vacuum tubing for cracks but have not discovered anything (unless there are recommendations to find hairline cracks). I could not check its ability to hold vacuum as I do not have a vacuum pump/gauge and they are rather expensive.
I also removed the IMRC actuator a while back, cleaned both it and its chamber, and put the valve back. I am beginning to think the valve was positioned incorrectly however, as I did not have a vacuum pump to rotate it to the correct position and rotated it by hand instead.
I have reset the ECM several times to see if the code returns and it normally does. On the last reset, I took the car for a drive, and waited for the DTC to return. After parking, shutting the car off and later returning and starting it, the DTC was triggered. I have attached the information below from the diagnostic if it may help to understand if the issue is a result of air flow.

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Friday, August 31st, 2018 AT 11:18 AM

12 Replies

AL514

MECHANIC
4,120 POSTS

Hello there, thanks for using 2CarPros. Yes, you are correct that you need to apply vacuum to the valve before installing it, once vacuum is applied (vacuum pump) there is a notch that lines up inside, you can see it while installing the valve back into the intake manifold. Hopefully this helps, the code is for the valve sticking too long and the ECM responding to it.

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Friday, August 31st, 2018 AT 2:07 PM

JJBURTON5

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27 POSTS

Thank you for your reply AL514. I will be sure to see if I can locate a vacuum pump in the near future. I will keep you updated.

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Friday, August 31st, 2018 AT 2:17 PM

JJBURTON5

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27 POSTS

Sorry for such the delay, I have a vacuum pump and I am readjusting the IMRC now. I will let you know.

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Friday, December 14th, 2018 AT 9:50 AM

JJBURTON5

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27 POSTS

I have just finished realigning the IMRC valve. I ensured that the tiny metal square inside the manifold lined up with the channel on the end of the spool valve.

After resetting the computer, the car drove perfectly and behaved well for the first trip. After stopping, turning the car off, and then turning it back on, the code has returned. I will be sure to reset the computer again tomorrow and then take some vacuum readings. Is there anything else I should try?

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Friday, December 14th, 2018 AT 1:48 PM

KEN L

MASTER CERTIFIED MECHANIC
42,959 POSTS

Hello,

There is a check valve that goes bad on these. Here is a diagram to show you how the system works and the location of the check valve below. You can test the valve manually. Check out the diagrams (below). Please let us know what happens. Cheers, Ken

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Monday, December 17th, 2018 AT 3:43 PM

JJBURTON5

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27 POSTS

Hello Ken,

I will be sure to check that valve. I would also like to mention that while I had the IMRC out, I tested the valve position sensor’s internal resistance and received a reading of 3.2 kohms, which I believe is correct (since I tested it inside the warmer garage). I am also certain that the valve holds vacuum, as I can hear the diaphragm “rebounding” when I attach the vacuum pump. My best guess is that it is likely a vacuum leak or electrical issue. I will proceed with testing and let you know.

Thanks,
Justin

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Tuesday, December 18th, 2018 AT 9:02 AM

KEN L

MASTER CERTIFIED MECHANIC
42,959 POSTS

Hi Justin,

It sounds like you are close to finding the problem. Please let me know.

Cheers, Ken

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Tuesday, December 18th, 2018 AT 10:34 AM

JJBURTON5

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27 POSTS

Hi Ken,

I am attempting to test the check valve. However, I’ve noticed it’s in an awkward position. Can I test the check valve by applying vacuum through the IMRC solenoid?

Thanks,
Justin

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Thursday, December 20th, 2018 AT 8:04 AM

KEN L

MASTER CERTIFIED MECHANIC
42,959 POSTS

Yes follow the diagram above it should flow one way only.

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Thursday, December 20th, 2018 AT 3:08 PM

JJBURTON5

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27 POSTS

Hi Ken,

I applied vacuum to the bypass solenoid valve and it held vacuum. As well, I also checked the voltage from the black and yellow wire on the imrc solenoid valve 2 pin connector to ground and it showed 11.57 volts. Furthermore, I connected the red and blue wire to body ground with a jumper wire, and received continuity at the ECM port 22 on connector B.

I will be testing vacuum and voltage at 5 rpm shortly.

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Thursday, December 20th, 2018 AT 3:20 PM

JJBURTON5

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Hi,

Great news, I have fixed my p1078 code. I went to a local scrapyard and found a 2004 Honda CRV. The intake manifold between these two vehicles were a perfect match, and I also grabbed the bypass solenoid and vacuum hosing. After cleaning the IMRC actuator in the new part, I discovered there were plastic pieces on the end of the rotary valve that mine was missing, likely lost by a previous owner who took it out prior to my purchase. Likewise, the vacuum hose on the bottom of the bypass solenoid had began to dry rot which made the tubing crumbly, this preventing a perfect seal. This has effectively solved my p1078 code!

Thanks,
Justin

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