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Q: Truck loses power and tries to stall

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I have a 2005 Nissan Titan. About a year ago I was having an issue with the truck losing power, trying to stall and running rough. The truck would run fine for about an hour or two and then would suddenly lose power, would not accelerate, back firing. If I pulled over and let it rest for a few minutes, it would regain power and I could go a short distance till it did it again. If I let the truck rest longer, it would go further before repeating the issue. The CAT light finally came on so I replaced the entire exhaust system. After that, the truck seem to run better but would still act up if I punched the accelerator to pass another vehicle. Now the issues is starting up again and it is getting worst. I was thinking of gutting the CATS but don't know?

My car has 231000 miles.
My car has an automatic transmission.

A: Hey there. This is a common sign of a fault...

Hey there. This is a common sign of a faulty ignition coil. Ignition coils are coated with a varnish-like insulation that becomes brittle over time after being stretched then contracted repeated as the copper beneath them expands and contracts at a higher coefficient than the insulation.

The insulation develops micro fractures that open when heated and close when cooled. When open, they allow shorting of coil windings and decrease or eliminate the coil’s ability to function. This type of temperature cycling happens because every time you shut the engine off, the fan stops running, the coolant stops flowing and the temperature under the hood rises. Every time you start the engine again the coolant flows, the fans turn on, and the temperature drops. The areas in and around the tops of the combustion chambers, the exhaust manifolds, and the exhaust components are hundreds of degrees hotter than the outside temperature under the hood. When this heat dissipates and is absorbed under the hood, it is trapped causing this cycling effect.

Components that contain heat sensitive materials include parts like coils, injectors, igniters, and some sensors. Any of these may be potentially subject to this same kind of heat problem which can be very difficult to trace. I would recommend having an expert from YourMechanic come to your location to take a look at your truck to properly diagnose the loss of power.

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