I got my 928 running under boost for the first time a couple of days ago. I'm getting about 5 lbs of boost at 5500 RPM and it seems to be working pretty well so far (BFG). I need to add a blow off valve, and am wondering if the 749's wastegate control logic handles high boost/closed throttle situation, like when shifting.

Also, I'm having trouble logging data from the 749. Datamaster and FreeScan both can connect but have trouble keeping synched up. I get data errors with Datamaster, Freescan just doesn't save any data. I've fiddled with the comm delays a lot (I know hte 749 is sensitive to this) and just can't get them to connect reliably. Anyone BTDT?

Thanks,

Bill
94 Z28A4
84 Porsche 928s Vortech/749
http://mywebpages.comcast.net/p-928/749.html

 

BOVs are easily done, manually.
A goggle for Mitsubishi Gen I, and BOV should find you some, and there's a how to on how to change the vacuum refering to make them pretty good. You can typically find them for like $35 with flange.

Maybe once we get the source code better documented, a more elegant answer will appear.

 

The 749 code does have provisions (i.e a table) for determining desired boost level given engine speed and TPS. And, there is a table for wastegate duty cycle vs. TPS. Unfortunately, I'm not very familiar with their operation. But, this is where I'd start looking...

I understand the problems you're having maintaining communications with the 749 controller. I've also run into similar problems. In the process of trying to eliminate outside interference, I ended up putting together a MAX232 interface with the shortest possible wires. This helped eliminate most of the "dropout" conditions I was running into. However, at times, it still takes a while (and a few tries) before I can get communications started with the controller. As you stated, the 749 is very touchy when it comes to the communication delays. Any noise on the line will likely wreak havoc....

Glad to hear you're having success with your car!

 

Just as a FWIW, the ecm is blind to clutch operation. Maybe a brake light switch on the clutch pedal, and that to the P/N input and then use the Charcoal Canister output?. Just thinking out loud with this.