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Discussion Starter · #1 ·
Back in February my CEL came on and when I checked the code it was P2070, Intake Manifold Tuning Valve Stuck Open. I tapped the solenoid or actuator with a the handle of hammer and the CEL went out the next day. All was good for a few months, then last month the engine lite reappeared, same code P2070. Tried the hammer handle trick again, but no luck. I can see the valve move if I go in and rev the motor and as the car goes back to idle, I can see the solenoid move the valve down. About 7 seconds later the solenoid moves the valve back up.

How do I troubleshoot what is causing the code? I know the solenoid is part of the manifold, but it appears it bolts on (3 torx screws), so if I can identify that as the problem, I can get one from an intake manifold at the junk yard. Any help or suggestions to diagnose/repair without replacing the entire intake manifold would be appreciated...thanks, Mike

PS I did spray a can of Seafoam in through the throttle body to clean any carbon deposits. Car has 105,000 miles.
 

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Welcome Aboard!:welcome:

You should introduce yourself here.

There are a number of engine smart people on here and maybe after the holiday they will start answering.
 

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Discussion Starter · #3 ·
Thanks...I bought this 2012 Cruse LS last August with 100,000 miles as a 1st car for a new driver. Overall it's been O.K. Just this CEL that is annoying. Car seems to run fine, not sure how gas mileage is since I don't fill it up. Anyway, I am trying to determine if the intake manifold tuning valve is actually working and just a sensor is misreading saying it is stuck? I watched the valve move like I explained in my original post, so it does not seem like it is stuck. Unfortunately, I could not find anything online related to Cruze's and this code/part. My hope is that it is just a sensor or part that I could get from the junkyard if it is on the intake manifold.

Thinking it is the actuator/solenoid since I got luck when I tapped it with a hammer and the CEL went out for a few months. I am just trying to avoid replacing parts "blindly." Hope there is somebody that experienced the same problem and can guide me in the right direction.:)
 

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Looking at my 2013 manual, the ECM monitors the position of the valve directly. The sensor is part of the actuator. So, the ECM sets a code if the actual position and commanded position differ for 5 seconds. Since the hammer trick worked, I'm thinking you're looking at a bad actuator or binding linkage. Damaged wiring or bad ECM is always possible, but I don't think it's as likely.

For some reason, the manual doesn't give instructions on replacing the actuator - it says to replace the intake manifold.
 

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Tuned intake and exhaust is as old the the hills, pulse wave travels at the speed of sound so if the length of this pipes is made resonant to a particular frequency, would get a tremendous increase in HP, but only good for a narrow rpm range.

Recall the 1993 GM 4.3L V-6 had such an intake tuning valve like this that was variable, and to be honest, I never understood its theory of operation. But it was gummed up with dried up conventional oil, cleaned it up with choke and carb cleaner and was good again.

Usually with any air leaks on an FI system into the intake manifold, the engine RPM would increase, this thing would barely idle and was tripping over its own feet. Just backwards. Coating the gaskets with non hardening Permatex gasket maker solved this problem.

Could try cleaning yours. Plastic has a thermal coefficient of expansion far different than other metals, never was much of a problem when everything was cast iron, describe this as a new problem that never was a problem before.

Carbon in our fuels is over a hundred year old problem and rather than trying to get rid of this stuff, adding tons of emission control problems that is even causing more problems. Friend showed me his quote for a new cat, cost more than what is vehicle is worth. Only reason why its there is because of carbon.
 

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Discussion Starter · #6 ·
Thanks for the information. I was leaning towards the actuator. Unfortunately, GM decided to not sell the actuator separate even though it could be a serviceable part (attached with 3 torx head screw). GM wants you to replace the entire intake manifold that would include the actuator and fuel injector rail. I will try to pick one up in the junk yard. My biggest concern is removing the rod that attaches from the actuator to the intake manifold tuning valve since it is plastic.

As far as cleaning the intake tuning valve itself, I did use the Seafoam in case there was carbon build up. But like I said, I watched the actuator move and move the valve, so it does not appear to be "stuck."

Thanks again, I will try to find on at a junk yard later this week. I will post my results once I find a junkyard willing to separate the actuator from the manifold. Enjoy your 4th of July holiday.:usa:
 

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I watched the actuator move and move the valve, so it does not appear to be "stuck."
Keep in mind it only has to get stuck once to trigger the light, but requires not happening for 4 ignition cycles to clear before the light turns off.

I'd check how freely the linkage moves.
 

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Discussion Starter · #8 ·
Good advise. I plan to do that once I have replacements in case I break something in the process...Murphy's law, try to do good and create more problems.
 

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Discussion Starter · #9 ·
Have not located my part at a "u-pull it", but had another question. I would like to get the entire "assembly", i.e., actuator, rod, and piece that attaches to the intake manifold tuning valve. The section that attaches to the intake manifold tuning (IMT) valve is attached by 2 torx screws, I assume if I remove them that part will come right off? I am concerned about disconnecting the rod from either end that it will crack and or "stretch" the ball fittings and not stay on when I reassemble. So, if I can get all three pieces already connected, it will ensure I do not have a problem with the connecting rod.

Looks like I will need to go to a local junk yard and explain this, so I want to make sure I know what I am talking about. Don't want to mess with mine till I have my replacement parts. Is my logic correct that if I remove the 5 torx screws, 3 on actuator and 2 on the part that attaches to IMT valve, everything will come off as one.

Any additional info will help. Thanks in advance.
 

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Discussion Starter · #10 ·
I finally located an IMT valve solenoid/actuator and replaced today. Good news is the P2070 code is gone, BUT NOW, I am getting another check engine light, P2078 - Intake Manifold Tuning Valve Position Sensor/Switch Circuit High Bank 1. Note I did not have that code before.

Now when I rev the engine while idling, I can see the solenoid engage and move the runner valve in the intake manifold, so it looks like it is working as it is supposed to. I do not know where to start to troubleshoot. If I clear the code it comes on immediately when I start the car. Have not researched anything yet, but any help or suggestions would be appreciated.
 

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Discussion Starter · #11 ·
Has anyone had the P2078 check engine light code? If so, what was your fix? Maybe I just got a "bad" IMT valve solenoid from the junk yard? Before I look for another, would like to know is there is some troubleshooting I could do to confirm. Any help would be appreciated...thanks in advance.
 

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Discussion Starter · #12 ·
Forgot to mention that I broke of the locking tab on the wire harness that attaches to the IMT valve solenoid when removing. After reviewing some other threads on other codes, could the P2078 be due to the wiring harness not seated completely? I did put a wire tie on it to keep it from coming off, but can not swear I pushed down all the way or that it stayed down since the tab is broke. This weekend I will push it down with the wire tie on and then without if the code is still present.

Any thoughts in the meantime from anyone? Looks like it is working based on seeing the solenoid engage every time I press the accelerator to the floor to rev the motor when in park. Working like I read it should, did not do this before with the old solenoid. If anyone has any experience with this code or how to troubleshoot, it would be appreciated.
 

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Discussion Starter · #14 ·
Thanks.That is what I am thinking, maybe some corrosion on the pins on the actuator or the wire harness is just not seated properly. Plan to check tomorrow. I appreciate your help.
 

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Discussion Starter · #15 ·
Looked at and cleaned the electrical connection, no luck, same P2078 code. For the fun of it, I put the old solenoid on to see what would happen now, i.e., P2078 code go away and P2070 code reappear. Turns out the P2078 code remained, but no P2070 code which was my original problem (without code P2078). Old solenoid now engages when I rev the motor, which it did not do before. So, now I am even more confused than when I started. I left the old solenoid on since it is now acting like the replacement. Will need to continue to search for answers.

Today I found another issue, water pump leaking from around the shaft. Usually not a problem, but access to the torx heads are below a pinch weld on the structure and there is only about 1.5" between the pulley and pinch weld, so I can not get my torx socket on due to the angle. I need some long torx sockets (I think) to get a lesser angle on the bolts to get enough bite to loosen/tighten them...nothing is easy anymore:( Unfortunately, the water pump leak puts the car out of service because it throws antifreeze all over as it hits the pulley. Thought I had a radiator leak, but after some checking found the leak when I checked the inside of the water pump pulley...
 

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Interesting...where does the wiring harness trace back to? Any melted/gnawed on wiring perhaps?

I've heard of very few water pump problems with the 1.8L motors; they are VERY common on the 1.4. At least it's relatively easy to get to on those...
 

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Discussion Starter · #17 ·
Replaced water pump today, purchased a set of "L" shaped torx head wrenches to get off pulley bolts. Everything came off easy, putting the belt back on and tightening the three bolts that hold the pulley was challenging. Now back to my P2078 check engine light code.

Unfortunately, the wires go into a harness and not sure where they go to. What's confusing is the IMT valve seems to be working as it should when I rev the motor in park. I need some basic troubleshooting instructions to try that don't involve a dealer scan tool. It runs fine. I wonder if there is a long term negative to the P2078 code?
 

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Discussion Starter · #18 ·
Update: Code P2078 gone and no P2070 either. The P2078 was a broken wire on the connector. It was not easily seen since the tape on the wires came down to the connector. Just got lucky to see the copper wire shine when I put a light on it. The break was at the top of the connector. I ended up pulling out the terminal with the broken wire and then pulled out a connector from my junk yard connector I cut off when I pulled the solenoid. Unfortunately I only had about 1.5 inches of wire above the connector and about 2 inches of loose wire in the harness, so it was hard to work with in a limited space. I used a butt connector to fix. Not my best tape job since I had to do it all with one hand, but hopefully enough to keep moisture out. Test drove the vehicle and no codes are pending, so I believe both the P2070 and P2078 are fixed.

Here is my summary of what fixed the problems:

P2070 - RUnner valve was binding some. When I disconnected the rod from the solenoid to the runner, I manually worked the valve open and closed 25-30 times to loosen it up if there was any carbon build up. I only say it was the runner binding since I ended up putting on the original solenoid and no P2070 code.

P2078 - This was self inflicted. When I was trying to remove the connector, I used a screwdriver to press in the tab to release the lock(since I could not get a hand in), but in the process broke the clip and probably the screwdriver slipped and cut the wire. I did not realize at the time that I did it since the tape covering the wires was down to the connector. So, fixing the cut wire eliminated the P2078 code.

I appreciate everyone help and comments during my endeavor.
 

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Glad you found it - I suspected a wiring issue. So you think the original problem was just the valve inside the intake got itself hung up? That would be good to know for other owners as this is somewhat common on the 1.8

Sent from my SM-G950U using Tapatalk
 

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Discussion Starter · #20 ·
Yes, because I now have the original solenoid on and no problem. I would recommend anyone with the P2070 code to first disconnect the rod to the runner valve that goes into the intake manifold and manually keep opening and closing the valve. There are "stops" so you can only turn it so far and it stops, so there is no concern about putting it back together in the wrong position. I will note again that I originally used a can of Seafoam intake manifold cleaner that I sprayed in through the throttle body to loosen up and clean any carbon deposits. The Seafoam did not fix the problem, but MAY have helped. Manually working the valve open and closed I feel fixed the P2070 code. So, even though when I started I could see the solenoid engage and move the runner, there must have been a slight amount of build up that prevented it from moving as easily as it should. Thanks again for everyone's suggestions and recommendations, it really helped me troubleshoot the problems.
 
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