2005 S-type 4.2 jerks on hard acceleration
#1
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I have had this car about two weeks now and noticed that if you accelerate from a stop with full throttle the car jerks strongly. I think it might be the traction control, but I have never felt a traction control system cut off the engine so much. I tried turning off the traction control with the panel switch but it still jerks. Any ideas?
#2
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I can relate. My 2004 XJ8 has done this. It makes me cringe to think of risking serious drivetrain injury if I need to nail it in order to jump out there. I thought it might have been a loose surface/traction control override, but whatever it is, I don't like it. I also feel a little slop in the drivetrain when hitting it (in 1st) after a slow roll to stop or near-stop. It feels like the trans is not hooking up soon enough, but instead connects after the engine has spun a bit (too fast), risking shearing something off? Has anyone else felt this?
#3
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Naturally, we'd like to see codes but there could be issues that won't throw them..."just yet". Have you run your cat in a heavy rain or car wash? Moisture that finds it way into engine and trans. electrical connectors will cause the shudder described. Snoop around a bit and/or let her sit to dry out.
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#6
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So far there are no codes. I will check again in a few days. No I havn't got anything wet that I know of. I have read about the transmission "lurch" on earlier models, but the symptoms don't sound the same, everything works perfectly in normal driving. It is only under full throttle acceleration from a stop or very low speed that it happens. It seems to me like an overly aggressive traction control.
#7
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So far there are no codes. I will check again in a few days. No I havn't got anything wet that I know of. I have read about the transmission "lurch" on earlier models, but the symptoms don't sound the same, everything works perfectly in normal driving. It is only under full throttle acceleration from a stop or very low speed that it happens. It seems to me like an overly aggressive traction control.
None of this will happen on dry pavement unless you've managed to break a tire loose and are 'burning rubber'. Go see your dealer and make sure you have the latest software version.
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#8
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Isn't the "Lurch" a condition evident when coming to a stop the trans. doesn't downshift quick enough into 1st before stopping and accelerating again? Check your O2 sensors, particularly the upstream's. Poor O2 signal can cause a lack of power and shudder under hard acceleration.
#9
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At least on my car, it was most evident when laying heavily into the gas after coming to a quick stop. The BANG! sounded like all six speeds were going end up in my lap and the shock felt like the car had been rear ended. YOW! I stopped lending the car to people for that reason.
The dealer did the usual software update and it's now much more subdued but I have also adjusted my driving style to compensate. There was an excellent post somewhere on the board describing a test ride with a ZF engineer who could induce the lurch at will. Must be in the archives somewhere.
The dealer did the usual software update and it's now much more subdued but I have also adjusted my driving style to compensate. There was an excellent post somewhere on the board describing a test ride with a ZF engineer who could induce the lurch at will. Must be in the archives somewhere.
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Throttle lag? Really? Does the 3.0 have it or I wonder if you have a fault that's surfacing as that?
What are your car's fuel trims at idle and 2500rpm (in P will do)?
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#14
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I'll check the fuel trims and get back to you. Car runs great, idles smooth, rev’s under load smooth. I do notice that at about 3500-4000 feels like the powerband really comes in, (form of Variable timing, or Variable intake??) Thx in advance.
#15
#16
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Did you guys ever find a solution? Mine is doing this as well. No check engine light. New transmission. Idle fine.
Happens when I step on the throttle on the downshift, feels like someone kicked the car in the rear and the wheel slips the locks for a second. Really dumbfounded here.
Happens when I step on the throttle on the downshift, feels like someone kicked the car in the rear and the wheel slips the locks for a second. Really dumbfounded here.
#17
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Did you guys ever find a solution? Mine is doing this as well. No check engine light. New transmission. Idle fine.
Happens when I step on the throttle on the downshift, feels like someone kicked the car in the rear and the wheel slips the locks for a second. Really dumbfounded here.
Happens when I step on the throttle on the downshift, feels like someone kicked the car in the rear and the wheel slips the locks for a second. Really dumbfounded here.
mine done this a couple of times after a new TCM was installed and was Reflashed and adaptions were reset .
if your trans is new , then I hope the TCM adaptions were reset . If so you need to take it easy , with no full throttle , no kick down , and no sport mode , for around 400miles.
if not you need to do so .
Last edited by Datsports; 07-30-2018 at 12:32 AM.
#18
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mine done this a couple of times after a new TCM was installed and was Reflashed and adaptions were reset .
if your trans is new , then I hope the TCM adaptions were reset . If so you need to take it easy , with no full throttle , no kick down , and no sport mode , for around 400miles.
if not you need to do so .
I'll take it to the dealership this week and see if I can get it flashed. How did you get it fixed, or did it just go away?
#19
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this is how you retrain the adaptions as i stated previously .
you need to take it easy , with no full throttle , no kick down , and no sport mode , for around 400miles.
#20
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Will it still reset the adaptions If I just drive it gently for the next 400 miles after being driven in sport mode, etc.?
Really appreciate your help!
Lately I've been thinking its the valve body and was looking at picking up a RevMax unit. I hope I don't have to do that.