Hi everybody, Today I was driving on the interstate using cruise control. I was accelerating to pass a truck using the steering wheel controls when suddenly I hear this bang from the rear end. The car bucks violently, the cel comes on with trac warning and restricted performance. Then without warning the car accelerates again without my assistance and the engine revs to about 6000. Really scary! Just took off. Lucky there was no car in my lane because I wasn’t in control. It only lasted a few seconds to get it back under my control and I turned off the cruise control and took it off the highway at the next exit. I have an OBD so I scanned it. The only code was a P0171 bank one. Now it’s running fine again and it was running fine before this occurred. The car has thrown various cel codes over the last 6 months. I replaced the battery and it helped. I’ve had a speed sensor cel and a too lean code on both banks. Plus I occasionally got an ABS warning. When the warnings came on I have taken apart the sensors and cleaned them thoroughly and put them back together. I have been lucky so far these remedies have worked. But the Big Bang from the rear end is mysterious. My Jag has 94k on it. I bought it last August with 86k. Does this event sound familiar to anyone? I will post some pictures as soon as I can figure out how. It’s a gorgeous Black Jaguar, garage kept, 2 owner, and I just waxed it with McGuires wax. That stuff is unbelievably good. Thanks for your opinions.

 

Welcome to the forums ROWKID,

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Graham

 

could be excessive pressure in transmission? - a drum about to go? the hint i think is you were cruising and then pressed the pedal down to pass, so it is likely you need the transgo pressure regulator. another possibility could be the fuel pump may be about to go or fuel filter is plugged. maybe the fuel cut out so thats why it felt like less power, and then it cut in again, and then it responded to the pedal being down.

 

That sounds like a good Big Bang Theory but I heard the show is being cancelled???

bob

 

The car may have accelerated because the cruise control kicked in as you had lost speed dropping a gear and go go to get back to cruise speed
as far as the bang was it a backfire or mechanical like in the driveline a coupling or universal joint if they are all ok then I would take it to get the gearbox checked/serviced