The cams for the 2000 Deville DTS are defective there is a Servive notice sent out to all Cadillac Dealers, However The dealers will not tell you about it in hopes you allow your car to exceed the manufactures warrenty. I was lucky the symptoms were present at 48888 miles. what are the symptoms: rough idiling when you are parked!
The 2000 Deville platform uses a different style engine mounting scheme that provides much better isolation at road speeds and less torque steer but , unfortunately (you know the deal about no free lunch..), has poorer idle isolation. The field complaints of
rough idle surfaced on the Deville once it started production in 2000 model year and prompted the cam timing changes.
The Northstar went to roller cams in 2000. The actual valve events are basically the same from 1993/99 with the direct acting tappets and in 2000/early 2001. Idle quality is measured several ways with the combustion stability and coefficient of variation
of indicated mean effective pressure (IMEP) being the most common and reliable. The combustion stability and CoV of IMEP for the 93/99 engines and the 2000 engines are virtually identical so one would assume that the perceived idle quality are the same. As the 2000 Deville production started it was obvious that with the build variation and mount variation this was not the case. The revised camshafts were developed to decrease overlap to improve the idle stability and perceived idle quality. That is what the service bulletin is about. There is nothing wrong with the earlier cams. They perform fine but in a DeVille...some DeVilles...the slight idle perturbations are not isolated by the mounting scheme sufficiently. By decreasing overlap the
performance is affected very slightly....and not to the better. That is why it wasn't done in the first place.
Why wasn't it found in testing? Well, it was...sort of. The engine itself was scrutinized considerably to determine and prove that the actual idle stability had not deteriorated. The
subjective tests in the car (DeVille prototypes) showed a slight degradation but it was not felt (no pun intended) to be complaint level. Unfortunately, in hindsight, this was not true and the effect of build variation was not totally comprehended. So, the
other cams were developed and released in record time. Now they are being made available to the field as a fix for a car with chronic idle quality concerns.
This idle concern is not a major issue to me personally. I have ridden some of the worst cars and , indeed, the engine does seem to shake more, but not to a complaint level.. It just has the feeling of a slight tremble like a higher perf cam would have.
But, this is a luxury car, so many owners (rightly so) demand an unperceivable idle. It is possible to provide that with the new cam profile. I would certainly not recommend that anyone just rush out and get the new cams nor would I let it influence the
purchase of a particular car.
Neither cam is "better" as one idles a little better and the other has a few more HP.
The 2000 Deville platform uses a different style engine mounting scheme that provides much better isolation at road speeds and less torque steer but , unfortunately (you know the deal about no free lunch..), has poorer idle isolation. The field complaints of
rough idle surfaced on the Deville once it started production in 2000 model year and prompted the cam timing changes.
The Northstar went to roller cams in 2000. The actual valve events are basically the same from 1993/99 with the direct acting tappets and in 2000/early 2001. Idle quality is measured several ways with the combustion stability and coefficient of variation
of indicated mean effective pressure (IMEP) being the most common and reliable. The combustion stability and CoV of IMEP for the 93/99 engines and the 2000 engines are virtually identical so one would assume that the perceived idle quality are the same. As the 2000 Deville production started it was obvious that with the build variation and mount variation this was not the case. The revised camshafts were developed to decrease overlap to improve the idle stability and perceived idle quality. That is what the service bulletin is about. There is nothing wrong with the earlier cams. They perform fine but in a DeVille...some DeVilles...the slight idle perturbations are not isolated by the mounting scheme sufficiently. By decreasing overlap the
performance is affected very slightly....and not to the better. That is why it wasn't done in the first place.
Why wasn't it found in testing? Well, it was...sort of. The engine itself was scrutinized considerably to determine and prove that the actual idle stability had not deteriorated. The
subjective tests in the car (DeVille prototypes) showed a slight degradation but it was not felt (no pun intended) to be complaint level. Unfortunately, in hindsight, this was not true and the effect of build variation was not totally comprehended. So, the
other cams were developed and released in record time. Now they are being made available to the field as a fix for a car with chronic idle quality concerns.
This idle concern is not a major issue to me personally. I have ridden some of the worst cars and , indeed, the engine does seem to shake more, but not to a complaint level.. It just has the feeling of a slight tremble like a higher perf cam would have.
But, this is a luxury car, so many owners (rightly so) demand an unperceivable idle. It is possible to provide that with the new cam profile. I would certainly not recommend that anyone just rush out and get the new cams nor would I let it influence the
purchase of a particular car.
Neither cam is "better" as one idles a little better and the other has a few more HP.
