Rodeo Engine

docdic · Feb 13, 2008

1993 964 Tiptronic, 87,000 miles A few days ago I removed and cleaned the ISV, as the engine was stalling when I stopped "" or, worse, when I hadn't stopped but was just slowing down in the outside lane in traffic to negotiate a roundabout. Being a tiptronic, the only answer is to glide onto the roundabout and start again "" to the great amusement of non-Porsche drivers"¦! This has happened in the past and cleaning out a gunked up ISV solved the problem. It is better now but not absolutely smooth. I also then found that the battery was flat and I had to start the engine using jump leads. Now, I have what seems to be a big problem "" the engine runs smoothly under normal driving conditions but if I use the kick-down, when it reaches 4000 rpm, the engine kicks and bucks and the rev counter becomes totally erratic, swinging wildly between zero and 7000 rpm. When I take my foot off the accelerator, it behaves normally again. This also happens if I accelerate smoothly after manually putting it into any of the gears "" again at 4000 rpm. I think that the engine is shutting off because it thinks that it has reached the danger limit but at 4000 rpm I am not yet going very fast and it has never happened before. Can anyone tell me what is the likely cause and what can be done to correct it, please?

Dave Wilkinson · Feb 13, 2008

Richard,

I'm not sure I have any answer - just a few thoughts. I'm wondering if the flat battery has caused some problem in getting some of the electronics "confused". Before attempting anything more complicated I think I'd be inclined to disconnect the battery for a few minutes (this will clear the DME memory), reconnect and take the car for a 20 minute drive using some decent performance once it's warmed up. This process will allow the DME to re-adapt to your driving style and "may" have some impact on the problem you are experiencing.

I'm assuming that the flat battery was because the car had been standing for some time. Was this the case??

From your description I think it unlikely that the problem is related to the ISV cleaning so the flat battery has got to be candidate no.1.

Report back when you can.

Regards

Dave

docdic · Feb 14, 2008

Dave,

Thank you so very much for your reply and advice. You were right on both counts - firstly that the battery was flat because the car had not been used for a while, and secondly that disconnecting the battery for a while and then driving it gently to start with has cured the problem.

I am extremely grateful to you and very relieved - I thought that something bad and expensive had happened to it somehow - possibly as a result of using jump-leads to start it.

Richard