This is my 2001 GRAND Marquis. 4.6L. 162K miles.
When it's between 15 and 30 degrees outside, moreso during snow, I have this weird "bucking" issue with the car. I'm worried that one of these days it's going to break the flexplate when it happens and it has caused me to lose traction driving int he snow when it happens.
It's hard to describe the condition that it happens, but it's super repeatable.
About 30 seconds after decreasing gas pedal input, the car will have one or a series of 3 or 4 big "bucks".
Example is - getting on the highway, then letting off once I'm at speed. Or if I'm going 65 on the highway and come to a hill, I let in a bit. Then once the road levels out, I let off. 30 seconds later the car will buck violently. I've had passengers think I hit something in the road or a giant pothole.
It's obvious the engine stops running for a split second. You can hear it in the exhaust. It doesn't do it when it's around 0F or above 25F.
The reason the buck is so violent when it happens is the torque converter is still locked up because I'm still on the throttle. If I touch the brake pedal lightly to unlock the torque converter, I can still feel it and you can hear the engine really lose RPMs, but then it recovers. Without too big of an event.
My first thought was some sort of vacuum controlled fuel regulator was sticking, but these cars don't have vacuum fuel regulators .. or any sort of mechanucal regulators at all.
My next thought was EGR valve was sticky or leaking. Maybe when I let off the throttle, the vacuum was trying to open it for part throttle cruise and it opened too much ... over the winter I replaced the EGR tube due to rust and put on a new Motorcraft EGR valve and DFPE sensor. Continues to do it.
It feels like in a manual if you let off and on the throttle violently. Except there's no springs in the torque converter to absorb the shock load.
When it's between 15 and 30 degrees outside, moreso during snow, I have this weird "bucking" issue with the car. I'm worried that one of these days it's going to break the flexplate when it happens and it has caused me to lose traction driving int he snow when it happens.
It's hard to describe the condition that it happens, but it's super repeatable.
About 30 seconds after decreasing gas pedal input, the car will have one or a series of 3 or 4 big "bucks".
Example is - getting on the highway, then letting off once I'm at speed. Or if I'm going 65 on the highway and come to a hill, I let in a bit. Then once the road levels out, I let off. 30 seconds later the car will buck violently. I've had passengers think I hit something in the road or a giant pothole.
It's obvious the engine stops running for a split second. You can hear it in the exhaust. It doesn't do it when it's around 0F or above 25F.
The reason the buck is so violent when it happens is the torque converter is still locked up because I'm still on the throttle. If I touch the brake pedal lightly to unlock the torque converter, I can still feel it and you can hear the engine really lose RPMs, but then it recovers. Without too big of an event.
My first thought was some sort of vacuum controlled fuel regulator was sticking, but these cars don't have vacuum fuel regulators .. or any sort of mechanucal regulators at all.
My next thought was EGR valve was sticky or leaking. Maybe when I let off the throttle, the vacuum was trying to open it for part throttle cruise and it opened too much ... over the winter I replaced the EGR tube due to rust and put on a new Motorcraft EGR valve and DFPE sensor. Continues to do it.
It feels like in a manual if you let off and on the throttle violently. Except there's no springs in the torque converter to absorb the shock load.
