I'm more familiar with FD tech stuff, but I just bought a 89 TII. Basically I was wondering what the stock map sensor is good for? With the FD, its upper range is 17 psi. Also, I know the stock boost gauge sucks, but i was wondering what the 450 mmHg is equal to? With the dawes device, I can't seem to bring the boost down...granted its got an open exhaust and intake. I might have to put the hi flow cat back on until I get the wastegate ported when it gets rebuilt. What happens when you go past the upper limit of the map sensor? I go flying by the 450 mmHg and at about 1/8 past the 450 range the check engine light comes on. When I hold the boost to the 450 line, no check engine light.

Any ideas?

Tim Benton
93 RX-7
91 RX-7
89 RX-7

 

The first thing you need to do is get a decent aftermarket boost gauge, especially if you're off the scale of the stock one! 450mmHg is 8.7psi, which is about where fuel cut should occur. I've got no idea what the limits of the pressure sensor are but it's probably a lot higher than that. A Dawes device won't bring boost down, no boost controller can.

 

Its only good for about 1 bar or 14.5psi...



-Ted

 

Thanks Jason and Ted for the info.

Tim

 

Not sure what you meant about the dawes device or any boost controller not being able to bring the boost down. Are you referring to the open intake and exhaust setup and boost creep? I plan on putting the hi-flowcat back on the car to have some backpressure....that should help with the huge over boosting.

Tim Benton

 

A boost controller raises boost by sending a lower pressure to the wastegate actuator. To lower boost you'd need to do the opposite, which is impossible.
Overboost and boost creep are caused by the FC's tiny wastegate not being able to flow enough to keep boost down once the exhaust and intake are freed up. The solution is to port the hell out of it. A cat will help but only because of the restriction to exhaust flow, which kills performance.