AFM Question

[kdubb]

Is the AFM for the 944 the same AFM for the 911 84-89?

[Aprilia]

You can't exchange them even though they basically perform the same function. The AFM for the 944 was made for the smaller 2.5L engine, so the draw from a 911 3.2L engine would open the flapper to a setting greater degree angle at a given rpm and signal the DME to dump more fuel than necessary into the intake. Theoretically, you could cobble together a system with a new fuel map on the DME or increase the flapper spring tension to match the 911 AFM flapper angles across a range of air flow volumes (in CFM). It would be much easier to refurbish a 911 AFM as long as the IAT still works.

[uwanna]

Originally Posted by Aprilia

You can't exchange them even though they basically perform the same function. The AFM for the 944 was made for the smaller 2.5L engine, so the draw from a 911 3.2L engine would open the flapper to a setting greater degree angle at a given rpm and signal the DME to dump more fuel than necessary into the intake. Theoretically, you could cobble together a system with a new fuel map on the DME or increase the flapper spring tension to match the 911 AFM flapper angles across a range of air flow volumes (in CFM). It would be much easier to refurbish a 911 AFM as long as the IAT still works.

Don't know about the 944, but this may somewhat throw a monkey wrench in your theory. The AFM for a 964 3.6 is the same P/N as a 3.2!
But I'm sure the "fix" was done in DME code.

[Morrie]

Furthermore... if the 944 is a later car, like my 89 944S2, the engine is 3.0 liters.....

[kdubb]

For responding. That was an excellent explanation.

[stlrj]

Originally Posted by uwanna

Don't know about the 944, but this may somewhat throw a monkey wrench in your theory. The AFM for a 964 3.6 is the same P/N as a 3.2!
But I'm sure the "fix" was done in DME code.

The AFM on my 87 3.2 came from a 3.6 964 and works perfect.

[Aprilia]

That is a good point. Our sponsor lists the 964 AFM as the replacement for the 3.2 911 even though the unit is lost likely pre-set for a 9% greater air flow. I expect that a 3.2 with the 964 AFM would run more lean across the rpm range but that could be automatically adjusted out by the closed loop O2 sensor or by adjusting the a/f mixture at idle.
With that in mind, it might be possible to get 3.0 944 AFM to fit a 3.2 911 if the IAT sensor range and values match.