[fast924S]

btsave, this is from FR_WILKS website. He does sell a chip that can fix the SHUDDER you are talking about, Also I thin you need to send him your DME to get a chip installed on the early 944


The early Porsche 944 has an engine shudder problem. As the engine returns to idle, the engine will drop several hundred rpm below idle and then return to a normal idle. This produces an engine shudder that is very pronounced and very unpleasant to the owner. It is a problem found only in the US DME version as imported into the USA and Canada from 1983 to mid year 1985. In Japan starting in 1982. This is not to be confused with the 944 motor mount problem that can also produces a shudder.


On deceleration (closed throttle), the fuel is shut-off temporarily. This done to save on fuel and cut pollution. The fuel flow is gradually reintroduced as the engine drops below 1,600rpm. The engine then returns to a normal idle condition. That is how the early Euro 944 functions._ The Euro 944 DME does not have the shudder problem.


In order to save on fuel, the US DME was redesigned for a fuel shut-off at 1,350rpm. Apparently this was a smog related change in the DME. The negative results to this change is, as the engines aged, they picked up this nasty shudder. My engine dropped to 600rpm before returning to normal idle of 950rpm. The shudder was very pronounced. The worst part of it is the shudder could not be fixed. It was internal to the fuel injection computer and swapping DMEs gets you another computer with the same problem.


There is now a bug fixed version of the software. I have modified the code to increase the fuel shut-off frequency from 1,350rpm to 2,000rpm. The code has been thoroughly tested and the shudder is gone!


NOTE: Not all early US Porsche 944 show symptoms of the shudder or it is so mild as not to be noticed.