Behavior Problems in drive train
Thread Starter
Teching In
Joined: Apr 2005
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Behavior Problems in drive train Gang,
When in traffic usually, in 3rd or 4th especially, running high 2's or low 3's in RPM, when I let off the accelerator, the whole car just does a extremely noticeable shudder. It feels like the fuel almost cuts out for a second. I took it into Cadillac (12000 miles on my 04 CTSV) several times, and of course the mechanic and I failed to make it happen then...aggh..
Anyways, I had the PCM re-programmed (airflow they thought might be the culprit... I knew better but let them do it anyways) and no problems in the fuel delivery system and after the recalled fuel rail was replaced, no difference, so it isnt the fuel.
I suspect its in the drive train, maybe the rear-end. The rear-end in does howl in 4th or 3rd gears (more predominant in 4th), like so many others in this forum reported, but I was wondering if this 'jerking' was also experienced as well, by those who have problems. My impression is that the splines maybe not aligned or something and provides backlash which causes the jerking... I don't know. Any words of wisdom appreciated.
Sincerely
VDriver.
When in traffic usually, in 3rd or 4th especially, running high 2's or low 3's in RPM, when I let off the accelerator, the whole car just does a extremely noticeable shudder. It feels like the fuel almost cuts out for a second. I took it into Cadillac (12000 miles on my 04 CTSV) several times, and of course the mechanic and I failed to make it happen then...aggh..
Anyways, I had the PCM re-programmed (airflow they thought might be the culprit... I knew better but let them do it anyways) and no problems in the fuel delivery system and after the recalled fuel rail was replaced, no difference, so it isnt the fuel.
I suspect its in the drive train, maybe the rear-end. The rear-end in does howl in 4th or 3rd gears (more predominant in 4th), like so many others in this forum reported, but I was wondering if this 'jerking' was also experienced as well, by those who have problems. My impression is that the splines maybe not aligned or something and provides backlash which causes the jerking... I don't know. Any words of wisdom appreciated.
Sincerely
VDriver.
Teching In
Joined: Mar 2004
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Make sure it isn't 'movement' of the differential. The bushings/mounts holdign the differential in place can twist/break, allowing the differential to move. When you come of the throttle, the reduction of torque allows the differential to snap back the other way. Not sure, but worth checking (it happened to me). Dan
Thread Starter
Teching In
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ok, yes my dealer called me up and said I need to take it in, probable rearend job, as they found others with similar problems. Now, the howl is getting worse like you suggest, and the sporadic behavior is more and more regular no, so at least they'll know and feel it too.
Also, been seeing other weird behavior like, random speed changes (up and down) when driving down slight inclines, which again sounds like the R/E to me, (actually I was blaming the fly by wire accelerator computer) but dont think thats it now.
Will make an appointment for next week....
Thanks. Vdriver.
Also, been seeing other weird behavior like, random speed changes (up and down) when driving down slight inclines, which again sounds like the R/E to me, (actually I was blaming the fly by wire accelerator computer) but dont think thats it now.
Will make an appointment for next week....
Thanks. Vdriver. 
Teching In
Joined: May 2005
Posts: 27
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From: Cincinnati, OH
Haqs anyone noticed a vibration while in 6th gear the final drive seems out of sorts with the rest of the gears. It seems at around 70 or so and a slow acceleration tsya 4 to 8 MPH increase the rear end or tranny seems to vibrate slightly.
Any of you expierence this?
Any of you expierence this?
Thread Starter
Teching In
Joined: Apr 2005
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Behavior fixed in drive train - reporting in Cadillac found the culprit with the jerking and surging I was experiencing with the car on this thread.
1) had the rear-end replaced to eliminate the howling. Its filled with synthetic now which they say will make it last longer. Howling is completely gone. Make sure you do the 500 mile break-in though...
2) now for the surging and jerking when letting off the gas. Since the car is fly by wire, theres a potentiometer on the gas pedal and a computer controls the throttle body. With the TECH2 plugged in, the diagnosis was wild variations in the throttle like 13-32-45-32-21-10% while the pedal pressure stayed constant say at 8%. So weeks went by with no apparent way of fixing it. Then when I used the cruise control for first time since I owned the car, it faulted out and recorded a mis-comm between the PCM and whatever and found it was the clutch sensor wire connector near the engine manifold that was broken/failing and now its all set and works like a champ again. So anyways, just reporting in. :-) Sincerely, VDriver
1) had the rear-end replaced to eliminate the howling. Its filled with synthetic now which they say will make it last longer. Howling is completely gone. Make sure you do the 500 mile break-in though...
2) now for the surging and jerking when letting off the gas. Since the car is fly by wire, theres a potentiometer on the gas pedal and a computer controls the throttle body. With the TECH2 plugged in, the diagnosis was wild variations in the throttle like 13-32-45-32-21-10% while the pedal pressure stayed constant say at 8%. So weeks went by with no apparent way of fixing it. Then when I used the cruise control for first time since I owned the car, it faulted out and recorded a mis-comm between the PCM and whatever and found it was the clutch sensor wire connector near the engine manifold that was broken/failing and now its all set and works like a champ again. So anyways, just reporting in. :-) Sincerely, VDriver
