2014 Infiniti Q50 3.7L will not rev past 2500 RPM

Hello all,

This is my first time going on a forum to ask the internet for help. I’m hoping I could find some solutions to the problems I am having at the moment. I recently bought a 2014 Infiniti Q50 3.7L Premium at 68k miles. I’ve only had the car for a little over a month and in that time I’ve had various issues. My main issues were what I believe to be timing and exhaust. One day I turn on my car and I am heading to work and I notice my car will NOT pass 2500 RPM. No matter how slow or fast I accelerate, the car just stutters once I reach 2500 RPM. When I am in park, neutral, or driving it will not go past it. It seems to be in a limp mode because when I reset my ECU… The issue would go away for a day or until I turned my car on/off a few times. So I go online and look for answers, between oil changes, and cleaning the MAF… I’ve done both and no fix. I had my close friend who is a mechanic take a look and he ran the OBD2 reader and I had a code for ‘[P0011] B1 “A” Cam Position Timing System Performance.’ He said my car is having timing issues. Unfortunately I didn’t have the time nor money to have it fully checked so I drove the car for a week in this “LIMP mode.”

My muffler had recently also disconnected and I had to pay to have new pipes welded and have it reconnected. A week later, the Y-Pipe/Flex Pipe completely disconnected as well. Odd thing is, while the Y-Pipe was disconnected, the RPM issue went away. As soon as I had it repaired, the RPM issue came back. Makes me believe they are somewhat related? With the flex pipe disconnected, the car was extremely loud, vibrated a lot, and rattled as well. Once repaired, the car is a lot smoother and quieter, however my car still shakes a lot. It shakes most when I am stopped while in drive, like at a stop light for example.

RPM’s while driving are wonky. When I slow down the RPM’s move around a little and sometimes spike real quick then go back down. Acceleration is extremely sluggish as well. Even in Sport mode which is quicker acceleration.

The muffler shop did a diagnostic and told me that my VVT Solenoids need to be replaced, my other mechanic told me they looked new… and I also had Midas do a full diag, and they told me there were no codes for timing related stuff. Just a bunch of missfires on cylinder 1. I am very confused as to what my problem is. I want to know so that I can fix it asap.

I do know that the previous owner did put in performance catalytic converters and did a resonator delete. I am not sure if that helps or not.

Any feedback is greatly appreciated. Thank you in advance!

Is the check engine light currently on? Did it flash when the rpm was restricted to 2500 rpm? If it was flashing you should not drive the car as further damage can be done if you keep driving.

Since the codes set were some time ago, they need to be read again. There are likely more than just a P0011. I’d guess that P0011 is a weak or clogged cam phaser solenoid given the mileage.

Also seems like you do not do your own service work, correct? If that is the case, you need to take the car to a well rated independent shop… not a chain like Midas… for diagnosis and repair. Pay the diagnostic fee. The repairs may seem expensive but in the long run they will be cheaper than throwing parts at the car blindly trying to fix one or multiple problems.

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Thank you for the response!

My CEL is not on but the reason for that is the bulb or instrument cluster itself. When I turn the battery on but not start the car, all of the lights on the dash turn on except for the CEL. Midas said it could be an instrument cluster or fuse. I personally believe either the previous owner or dealer tampered with it. I would not have purchased a car with a CEL on.

I am going to have the codes read again since I just fixed the Y Pipe and the issue came back.

The car is telling me I am averaging 15mpg. I am at the gas station every few days lol.

I don’t do my own work but I have had my certified mechanic take a look, a independent muffler shop diag and a midas diag and im getting different answers.

I do have an extended warranty that I plan on using for repairs, however that process is long and won’t kick in for a while. I’ve spent hundreds of dollars already and this is my first car that I’ve bought on my own. This whole process has been hell and it seems like I’m stuck with the car.

If your mechanic cannot read engine codes such that you must go to Midas for this, you need a better equipped mechanic. Yours is not right for this car. You really need the CEL fixed, it is the only indicator of a problem you may have.

You should have had a qualified mechanic inspect the car before you bought it. Take that as advice before the next car purchase.

BTW the Y pipe has nothing to do with a P0011 code.

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That indicates there’s an exhaust restriction, and the engine can’t breathe.



“I do know that the previous owner did put in performance catalytic converters”

Another indicator of your thought

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So the restriction would be somewhere in the Y-Pipe or the exhaust? Since the Y-Pipe disconnected from where it connects to the cats. Possible clog?

Thank you for your response.

There do seem to be at least two separate problems here. The next time a mechanic looks at it, ask specifically for a check of intake manifold vacuum at elevated RPM. If there is little vacuum at 2500 RPM with no load on the engine, that suggests an obstruction in the exhaust, which we suspect because you indicated that the disconnected exhaust pipe changed its behavior. However, it may be that the computer was running in open loop mode with the exhaust pipe broken, .

As for the code, something is not right with variable valve timing. First thought: Those systems are sensitive to oil viscosity. Is it possible that the previous owner put in really viscous oil or oil additive to try to hide a problem with an oil leak or oil consumption? You can try an oil change with the proper oil and see if it helps.

I fear that this car is going to be an expensive learning experience. Sorry.


Thank you for your very informative response!

I will definitely relay this test to a mechanic to see if that is the issue. Unfortunately the previous owner did not have any service history from 25k -68k miles (purchase mileage). I’ve already done a complete synthetic oil change yesterday so I am going to see if that does seem to help with anything.

I do fear it’s going to be an expensive learning experience. Unlucky for me, I didn’t do enough research/inspection prior. The dealership I bought from is full of what appears as fraudulent activity, they haven’t been very helpful. I also wish I would’ve seen the CEL light on from the beginning, as I would’ve never purchased the car had I known there was issues.

Thank you for your response, however.

I would weigh in on this but my gut feeling tells me this vehicle has some serious problems that are all related.


A broken cel light is tampering. Fraud in my book


I missed the part about the CEL light not working on Key On. Agree with Cavell that this is almost certainly tampering. Regrettably, you can’t prove that dealer did it unless you find their fingerprints on the back of dash cluster, and Illinois is a “buyer beware” state with regard to automobile transactions. Based on what I see on the internet, if the car is sold in Illinois “as is”, the seller is held harmless under virtually all scenarios.

This really sucks. Do you know if Indiana has those same rules? I bought the vehicle in Indiana right on the border of Illinois. I wonder if they have different laws. Either way, the fact that they sold me a car with the amount of problems I’ve had in less than a month, is ridiculous. I’m 20 years old, working full time and have a lot of bills to pay like everyone else. While I can afford the car, I can’t afford taking it for diagnostics and repairs every week.

Regardless, it’d be close to impossible to prove any fraud against a dealership. My only hope is that the warranty covers most of the issues and I get it all fixed. First step is figuring out what those problems are. ALSO most warranties don’t even cover exhaust and oil related issues so… that’s that.

I appreciate all of your feedback and attention, however!

Look at your paper work . If it says ’ Sold as is ’ then the dealer does not have to even talk to you.

Of course it is too late now but with lots of bills to pay why did you nor buy something that gets better fuel mileage and does not have LUXURY name plate .


I CAN afford regular maintenance , gas, etc… however I don’t believe any average person can afford being in the shop getting repairs/diagnostics every week even with a normal/average car.

My situation sucks and there’s no one to blame but myself. I only wish I would’ve inspected/known about the car better lol

I’m sure that this varies from one state to another, but in my state, a vehicle that is sold “as-is” has to have a large notice pasted on the side window stating that this is the case. Does the OP recall anything like that?

In any event, the sale contract should state either the terms of the limited (usually 30 days) used car warranty, or it should state that the vehicle is being sold “as-is” without any type of warranty.

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Additional question, I have reset the ECU and the problem goes away for a little while then eventually resurfaces. Does that indicate the computer is putting my car in some sort of LIMP mode?

Wouldn’t an exhaust restriction still be there even after resetting the ECU?

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The PCM places the engine in limp mode when a fault is detected, engine speed is limited to 2500 RPMs to protect the engine and reduce emissions.

Focus on repairing the variable valve timing fault, this should only require one diagnostic test, not one every week.

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Thank you :slight_smile:

It does sound like the car is going into a limp mode. My limited experience is that limp mode is cleared when the car is turned off and does not activate again until the car reaches the condition of RPM, load, and temperature that triggers limp mode again. However, it sounds like on this car, limp mode is cancelled only by resetting the PCM.

You are correct that an obstructed exhaust would still be obstructed after a PCM reset, but it may take a certain set of conditions for the PCM to conclude “Wait a minute - this combination of RPM and load and throttle opening and manifold pressure and mass air flow don’t fit together - something is very wrong!” and it goes into limp mode…

Though the exhaust may be obstructed, that would not make the car shake and idle rough. For that I would look for the cause of that camshaft timing error code. A common failure point on cars is the camshaft position sensor, but that has its own code so it seems unlikely that it is the problem here.

At 7 years and 68k miles, you are out of the Infinity warrantee period. There is a remote chance that you might get some help from the Federal Emission Performance and Defect Warranties – 96 months/80,000 miles, but with modifications done to the car, I would bet against it. In addition, the modifications you have discovered so far may not be the only ones. Sorry.

It could be worse. When I was your age, I bought a Vega.

We all get bitten sometimes on used cars. When I was 60 years old, I wanted a white BMW wagon with a stick shift. I finally found one with 100k miles on it. I paid $10k. I spent 6k and many hours over the following two years on that car. The good news is that I still have it, now with 252k miles on it, so the /mi did not turn out to be too bad.

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