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Matt, Engineer
Category: Transmissions
Satisfied Customers: 21856
Experience:  Mechanical Engineer BEng Hons22 years experience in car engine industry, 10 years in formula 1
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I have a 2013 Nissan Pathfinder. I bought it used with 34,000

Customer Question

I have a 2013 Nissan Pathfinder. I bought it used with 34,000 miles. 1 month after I purchased it, the transmission had to be replaced due to lack of acceleration. It hasn't even been a year since then and I have been having a grinding/popping noise/sensation when accelerating, I can feel the popping in the gas pedal. At first it started only doing this at 20-40 mph, but not it does it from 5-80 mph. I have been to the Nissan dealership multiple times and keep getting told it wont duplicate. Which is a lie, because I did 2 test drives with the mechanic and it did it for him when he drove. They think its the transmission again, but nothing is coming up on their "Test". Please help I need some answers.
Submitted: 2 years ago.
Category: Transmissions
Expert:  Matt replied 2 years ago.
Hello its possible that the issue is one with the engine and not the transmisson,This could be an airleak after the airflow meter, any air dragged in here isn't 'seen' by the ECU and so not compensated for and can lean the engine out and can also allow the engine to rev up when not desired causing rough running.As its a mechanical fault it tends not to turn on the fault light and you can sometimes hear a 'hissing' noise with the engine running. Check the hose clips for tightness and inspect the trunking for any cracks or splits and also all the vacuum system, the small bore pipes and fittings for cracks and missing parts. The best way to locate a leak is to have the engine running and warm and then spray lighter gas /propane around each joint in turn. If the engine rev's up you've found your leak.Now you might think that spraying lighter gas around a hot engine isn’t wise, however the flash /ignition point of gas is about 400°C so you need a naked flame or spark to set it off and I’ve used this method for many years without incident.Work your way through each possible joint one at a time and you should find it. I use a slightly flattened piece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas into each area, especially those difficult to reach with large implements. It’s also worth getting the fuel pressure checked as if this is low due to a blocked filter or faulty regulator or even a poorly pump will all result in insufficient fuel being delivered to the engin
Expert:  Matt replied 2 years ago.
do you still need help ?