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Ron
Ron, ASE Certified Technician
Category: Nissan
Satisfied Customers: 35857
Experience:  34 years of automotive Repair
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Having issues with 2007 Nissan Sentra (which I have owned

Customer Question

Having issues with 2007 Nissan Sentra (which I have owned for 3 years): Hard time starting after 8+ hours after the car has sat. My mechanic replaced a ruptured air tube and cleaned the mass air flow sensor. The starting issue was still a little off and he instructed me to bring to dealer and have them perform a relearn. In the interim the service engine light came on and I experienced the car running rough (had a hard time accelerating). Drove directly to dealer. Dealer repair states the cam sensor and crank sensor have to be replaced. Repair did not solve the problem. Dealer said there was “junk” in the engine and the sensors could not make contact. I allowed them to perform an engine flush and that might solve the problem. It didn’t. They say the starting is better the car drives fine and that it might be a timing issue. Picked up the car on Saturday let it sit and attempted to drive to work on Monday and still same issue: hard starting, jerky motion when accelerating and high rpms. I nursed it along to get to a Nissan dealer near my office. I did notice on several circumstances - while coasting and once I accelerated and reached approx. 55mph - the car seemed to behave normally! Go figure. Now the car is at another Nissan dealer and the cam and crank sensor issue has popped up again! I told them this was replaced not less than a week prior. Now they’re trying to determine if it is a timing issue. Trying to be proactive I researched my car’s “symptoms” and recent repair and have discovered the following: mass air flow sensor can have the following symptoms - The engine stalls soon after starting, The engine drags or hesitates when idle or under load, The engine hesitates and jerks during acceleration, The engine hiccups, The engine displays unusually lean or rich idling. This mirrored my exact experience. I told this to the current dealer and they just keep following the codes - cam/crank sensor and timing. The article also stated that the air flow sensor may not “code”.
My question: is it more likely a timing issue or the mass air flow sensor?
Submitted: 2 years ago.
Category: Nissan
Expert:  Ron replied 2 years ago.

Hello and thank you for your question, can you tell me the actual fault codes you are getting when the light comes on?

Customer: replied 2 years ago.
My apologies I do not have invoice with me that might list the codes.
Expert:  Ron replied 2 years ago.

If you can get me the actual fault codes when you can we can work from there , don't let them replace anything until I can advise you on the next steps if you can.

Customer: replied 2 years ago.
My invoice states po340.
Customer: replied 2 years ago.
BTW, The service engine was not on when I brought it to the second Dealer.
Customer: replied 2 years ago.
Additional info: Exhaust issues - I have replaced the muffler twice and the catalytic converter once within 2.5 years. Don't know if it is relevant.
Expert:  Ron replied 2 years ago.

This is a Cam sensor code and if the sensor has been replaced and the problem is still there then you may very well have a timing concern. I would go ahead and try cleaning the MAF sensor with some MAF cleaner and while doing so, be sure to disconnect the negative battery cable. If the problem return see what fault code and or codes resets and post back with the results. The most common cause for the code P0340 is in most cases caused by a problem with the timing chain.

Customer: replied 2 years ago.
Update - brought the car to my regular mechanic. He verified that the timing was off. After much delay with getting the necessary parts the car was repaired. I picked up the car this morning, drove to work fine and then on the trip home the same old problem. Do you have any advice on how where to go next? I think after all this time and effort the car now is a total loss.
Expert:  Ron replied 2 years ago.

I suspected the timing was off, are you sure he got it lined up correctely?