Lurching Problem
Back to lurching.
To recap what we are talking about here, the Cayenne has a hesitation or lurching characteristic that has been noticed by drivers since the car was introduced. Automotive journalists testing the Turbo have wrote of it's turbo lag however I believe it is the same throttle response issue Cayenne S owners see. From a stop or at part throttle operation the Cayenne will sometimes hesitate for a second or more when the throttle is partially depressed and then accelerate rapidly. Some describe it as a delay in transmission downshifting while others describe it as a throttle issue. I believe it is a combination of the two.
Edmunds.com recently tested the Cayenne (review) and has a fair description of the issue:
In my research of this subject I find there are two components to the lurching issue: a documented transmission problem and an undocumented DME remapping issue.
First the transmission issue. This is a Technical Service Bulletin, #3303 or NHTSA #284737, issued in August 2003. TSB's can be checked on the NHTSA website: NHTSA
There is a faulty thermostat in the transmission that causes shifting problems. It can affect all Cayennes with automatics starting with the Cayenne introduction. I have heard from one source that it only affects 2003 models. I have also heard the problem exists through June or July 2003 builds which would include some model year 2004 Cayennes. I have a 7/1/03 build and the dealer checked my serial number for this TSB and said it was not affected by this bulletin. The bulletin itself says it affects some 2004 models so I think it is probably through June 2003 builds.
I don't have direct experience with this TSB but I have seen descriptions that look much like the lurching issue. In general, the transmission does not downshift as quickly as it should under certain circumstances. In this case it may have had something to do with transmission temperature.
Now for the DME remapping issue. This is undocumented by Porsche but information on it is becoming clearer. The remapping has been available for at least a month now but has only been presented as a solution if you asked the right questions or made certain specific complaints. The Porsche District Service Managers are providing instruction on the update. I had the procedure performed on my car earlier this week. My service invoice gives the code 24701999.1.0 and 247006660001. The first code is the same given by another member on this forum.
The results of the update are not yet clear to me. I believe throttle response is better but this is a difficult situation to judge and I need more time with more driving situations to really evaluate this fully. Some who have had the update are more enthusiastic. I still think the response can be improved. I have an X-5 in the household for comparison and I believe the BMW is smoother shifting and the throttle more immediately responsive.
The answer is in the mapping of the DME which controls all shift points and throttle activity. I have watched the transmission gear indicator during the hesitation. Many times the lurch is caused by a delay in transmission downshifting. But, at other times, if the gear indicator can be believed, the transmission is already in a lower gear but the delay is still present. This was my experience prior to the update. As I develop more experience with the revised mapping I will post updates here.
To recap what we are talking about here, the Cayenne has a hesitation or lurching characteristic that has been noticed by drivers since the car was introduced. Automotive journalists testing the Turbo have wrote of it's turbo lag however I believe it is the same throttle response issue Cayenne S owners see. From a stop or at part throttle operation the Cayenne will sometimes hesitate for a second or more when the throttle is partially depressed and then accelerate rapidly. Some describe it as a delay in transmission downshifting while others describe it as a throttle issue. I believe it is a combination of the two.
Edmunds.com recently tested the Cayenne (review) and has a fair description of the issue:
Quote:
Stomping on the throttle from a dead stop results in a half-second of tepid forward movement as the turbo spools up - then bam! Like Anna Nicole after spotting a Krispy Kreme, the Cayenne Turbo somehow ignores its considerable heft and simply springs into action.
A similar response occurs once the vehicle is in motion, though throttle response continued to be a notable issue for most drivers. Sometimes forward motion comes after a slight delay, other times it comes on stronger than expected (or desired). The effect is more subtle than overt, but drivers used to the refined nature of an Acura, BMW or Infiniti will notice it. We're not sure if this behavior is turbo- or transmission-related (or a combination of both), but after trolling the Cayenne car discussions boards we found several owners who had visited their local dealer to have the drivetrain controller "reflashed" with positive results.
The transmission itself proved capable of delivering positive upshifts under full-throttle conditions, and when set in "Manual" mode, it would respond quickly to up- or downshift commands sent via the steering wheel switches or shifter movement. But when left in automatic mode, with varying levels of throttle applied, it sometimes seemed to hesitate before choosing a gear. It's worth noting that Porsche has designed this transmission to "learn" driver behavior and respond accordingly. What this is supposed to result in is a transmission that "knows" when the driver wants it to hold gears during aggressive on- or off-road driving. To us, it seemed like the transmission performed well when fully engaged in either standard or aggressive driving mode, but it sometimes switched modes too early or too late (a difficult situation to avoid whenever a transmission is allowed to think for itself).
In my research of this subject I find there are two components to the lurching issue: a documented transmission problem and an undocumented DME remapping issue.
First the transmission issue. This is a Technical Service Bulletin, #3303 or NHTSA #284737, issued in August 2003. TSB's can be checked on the NHTSA website: NHTSA
There is a faulty thermostat in the transmission that causes shifting problems. It can affect all Cayennes with automatics starting with the Cayenne introduction. I have heard from one source that it only affects 2003 models. I have also heard the problem exists through June or July 2003 builds which would include some model year 2004 Cayennes. I have a 7/1/03 build and the dealer checked my serial number for this TSB and said it was not affected by this bulletin. The bulletin itself says it affects some 2004 models so I think it is probably through June 2003 builds.
I don't have direct experience with this TSB but I have seen descriptions that look much like the lurching issue. In general, the transmission does not downshift as quickly as it should under certain circumstances. In this case it may have had something to do with transmission temperature.
Now for the DME remapping issue. This is undocumented by Porsche but information on it is becoming clearer. The remapping has been available for at least a month now but has only been presented as a solution if you asked the right questions or made certain specific complaints. The Porsche District Service Managers are providing instruction on the update. I had the procedure performed on my car earlier this week. My service invoice gives the code 24701999.1.0 and 247006660001. The first code is the same given by another member on this forum.
The results of the update are not yet clear to me. I believe throttle response is better but this is a difficult situation to judge and I need more time with more driving situations to really evaluate this fully. Some who have had the update are more enthusiastic. I still think the response can be improved. I have an X-5 in the household for comparison and I believe the BMW is smoother shifting and the throttle more immediately responsive.
The answer is in the mapping of the DME which controls all shift points and throttle activity. I have watched the transmission gear indicator during the hesitation. Many times the lurch is caused by a delay in transmission downshifting. But, at other times, if the gear indicator can be believed, the transmission is already in a lower gear but the delay is still present. This was my experience prior to the update. As I develop more experience with the revised mapping I will post updates here.
. Which leads me to apologize for some of the venting I've unintentionally been doing. I'm just very disappointed and I agree that it's not helping to resolve the issues.
I guess quality control works pretty good at Porsche now and they try hard to keep a high quality level because the Cayenne is a very important product for them.
