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Jay
Jay, Certified Infiniti Technician
Category: Infiniti
Satisfied Customers: 19670
Experience:  20+years, Nissan and Infiniti experience and currently now working for a Infiniti Dealer
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I have a 2012 infinity m37 that only starts if i unhook the

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I have a 2012 infinity m37 that only starts if i unhook the bank 1 cam sensor or mas airlow sensor with either or diss connected but with connected it wont start??? Need help asap thanks

Hello my name is ***** ***** thank you for your question.

Normally if you unplug a Cam Sensor and the vehicle will start, that is a sign that there is a timing chain issue. Such as it jumped time. How many miles do you have on your car?

Customer: replied 4 months ago.
62 k miles

If you do have something timing chain related, that would be covered under powertrain. Your powertrain warranty is 6 years or 70k miles. So you may want to let the dealer look at this for you.

Do you have any more questions on this?

Customer: replied 4 months ago.
The only way to be sure if its timming i am going pull off the whole timing cover or i can do it another way ??

If you pull the front timing cover, you would void the power train warranty.

What I would do is if it runs with the MAF sensor unplugged, I would monitor intake timing operation to determine if there is a timing issue. If it only runs with the cam sensor unplugged, then 100% sure there is a timing issue.

I would not dig into the engine unless you are sure. Other wise, the dealer will void the powertrain warranty cause they would consider it tampered with.

If you have any more questions on this, please feel free to ask.

If not, and you're satisfied with my help, please Rate me. That is how I get credit for my work. I hope I have provided you with Excellent Service.

Thanks Jay!

Customer: replied 4 months ago.
i think someone had worked on it and dealer is not going to offer any warranty repair i am a repair shop and this car was purchased at the acution. So i need help figuring this out if you can help please advise what i cant to resolve this thanks

You said it runs with the MAF sensor unplugged right? Which one? or both? Meaning do you have one or both MAF sensors unplugged?

Customer: replied 4 months ago.
Only bank 1

Bank 1 Cam Sensor and Bank 1 MAF sensor?

Customer: replied 4 months ago.

This does sounds like something is up with the timing on Bank 1. Do you have a scanner to monitor intake timing?

Customer: replied 4 months ago.
Wit maf unpluged runs for 30 sec very rough but with cam unplugged engine runs good but car drives in safe mode
Customer: replied 4 months ago.
i have a autel maxi sys

Thank you.. That pretty much verifies that there is a issue with the timing chains. That pretty much verifies that it is timing is off a 2 teeth.

When doing timing chains, this is one trick most people don't know and never do and it burns them all the time and they come here asking questions.

Before you do any timing chain work, since you can at least get your car to run, pull the fuel pump fuse or unplug the fuel pump and allow the vehicle to stall out before starting. Then you do your timing chain work. Once you are done, leave the fuel system disabled and turn the engine over to build oil pressure to the chain tensioners. Failure to disable the fuel system could allow the engine to fire right up before the tensioners build pressure which could allow the engine to jump time.

That is most likely your issue!

If you have any more questions on this, please feel free to ask.

If not, and you're satisfied with my help, please Rate me. That is how I get credit for my work. I hope I have provided you with Excellent Service.

Thanks Jay!

Customer: replied 4 months ago.
I understand but i have not touch the timing for it be it looks like there could of been a possibility someone else before the car came in my hands but my questions in regards ***** ***** suggestion that timing can be off how and what would be the fastes way to verify the timing on this engine?

Unplugging the Cam sensors is actually one way to verify a timing issue. So you actually did the right trick.

Since you have no history on the car, you don't know if anyone was in there or if the engine was low on oil once which allowed it to jump time either. So the first thing you are going to need to do is the timing chains.

I have a video showing somethings about the timing chains if you want to view it. Some tricks and how it lines up and so on..

Customer: replied 4 months ago.
I will try that and let you know tomorrow how that worked out

You got it.

Customer: replied 4 months ago.
I have not got a chance i will let you know soon

You got it!

Customer: replied 4 months ago.
Hey jay verified the timing is on the mark points... it's not the timing secondary and primary....
Customer: replied 4 months ago.
Sorry for the late response Just been busy with other stuff thanks

Do you still have it apart?

If the timing is all lined up, then it's most commonly a bad intake sprocket.

Customer: replied 4 months ago.
How can I verify the sprocket is working properly before changing it out each sprocket is $600 and I would want to change them both because taking the risk to go back in there again... thanks

If the timing is correct, since the sprockets operation is to Oscillate back and forth. If one is locked up, it would also act like it's out of time. Which could also explain why it runs with the Cam Sensor unplugged. When you unplug one of the Cam Sensors, it defaults all the readings to the one side. That is why it runs. So yes, I would agree. If you are in there, if one sprocket is bad, I would replace them both.

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