Cayenne Throttle Response/Hesitation
The Porsche Cayenne has been plagued with reports of poor throttle response since it's introduction. It goes by many names: lurching, lag, hesitation, delay, dead pedal, etc. The car does not always respond quickly enough to throttle inputs and you may experience delays of one or two seconds after flooring the gas before it finally takes off. The most severe example is in merging onto a freeway when you can sometimes find the Cayenne almost stalling when you hit the throttle, which can leave you in a stressful situation if you had planned, for example, to pull in front of a fast moving truck. When it does take off it does so in an unexpected rush rather than a smooth flow of power. The delay seems attributable to both the throttle and the transmission. The engine does not respond immediately to throttle input and the transmission is frequently in one or two gears too high for good acceleration. Exiting a corner is also a frequently cited example of the hesitation, where the Cayenne will frequently stumble and hesitate when you apply the throttle coming out of a corner.
Porsche is aware of the complaints and has been working on a solution, although most of this work is undocumented. The most recent possible solution was a replacement of the transmission control module. This was the topic of an extensive discussion here on Rennteam (see this thread). Many Cayenne owners had their transmission control modules replaced to help reduce the delay and the results were discussed in that thread. To summarize, the transmission control module replacement was no cure by itself but may have been helpful. It would seem to apply to Cayennes built prior to June 2003. A characteristic of the old module is that the car starts off in D2 when PSM is turned off. The new module starts off in D1 when PSM is turned off. There may be other module replacement activities going on as well but this seems to be the main one and in fact it may be the subject of Porsche's recall/TSB #W515 issued in late September 2004.
Another possible solution has been a DME update. Many dealers have performed DME updates for owners who complain of the hesitation. Most of these updates were undocumented and not entirely successful in curing the symptoms. There is a recent DME update, W515, also issued in late September 2004, that is documented. I have not read the bulletin so I am not even certain it is directed at the hesitation issue, however I have had the procedure performed on my car and believe it has made a difference. It's only been two weeks so I'm still evaluating.
I would like to hear from anyone who has had either of the most recent recalls performed on their cars, either W515 or W516, and what they think the results are. Also anyone who had a transmission control module replacement prior to that recall should continue to provide us with updates.
Porsche is aware of the complaints and has been working on a solution, although most of this work is undocumented. The most recent possible solution was a replacement of the transmission control module. This was the topic of an extensive discussion here on Rennteam (see this thread). Many Cayenne owners had their transmission control modules replaced to help reduce the delay and the results were discussed in that thread. To summarize, the transmission control module replacement was no cure by itself but may have been helpful. It would seem to apply to Cayennes built prior to June 2003. A characteristic of the old module is that the car starts off in D2 when PSM is turned off. The new module starts off in D1 when PSM is turned off. There may be other module replacement activities going on as well but this seems to be the main one and in fact it may be the subject of Porsche's recall/TSB #W515 issued in late September 2004.
Another possible solution has been a DME update. Many dealers have performed DME updates for owners who complain of the hesitation. Most of these updates were undocumented and not entirely successful in curing the symptoms. There is a recent DME update, W515, also issued in late September 2004, that is documented. I have not read the bulletin so I am not even certain it is directed at the hesitation issue, however I have had the procedure performed on my car and believe it has made a difference. It's only been two weeks so I'm still evaluating.
I would like to hear from anyone who has had either of the most recent recalls performed on their cars, either W515 or W516, and what they think the results are. Also anyone who had a transmission control module replacement prior to that recall should continue to provide us with updates.