Pressure/Boost testing the vacuum system
#1
Pressure/Boost testing the vacuum system
Boost tests are a staple in the DSM world. Cap off the turbo inlet and apply pressure. If you're lucky nothing will start making noise till you've got 15 or 20 psi in the whole system.
I wanted to check my stock twins for any leaks so I capped off both turbo inlets. Whether I apply pressure directly to the UIM or to the Y-pipe, I can't build ANY pressure in the system at all. It's all going somewhere too quickly to even register on the gauge. I sprayed soapy water around, listened everywhere, etc. and I couldn't find any obvious leaks. Is this "just the way it is" with a rotary or am I missing something obvious?
Thanks!
I wanted to check my stock twins for any leaks so I capped off both turbo inlets. Whether I apply pressure directly to the UIM or to the Y-pipe, I can't build ANY pressure in the system at all. It's all going somewhere too quickly to even register on the gauge. I sprayed soapy water around, listened everywhere, etc. and I couldn't find any obvious leaks. Is this "just the way it is" with a rotary or am I missing something obvious?
Thanks!
#4
RX-7 Bad Ass
iTrader: (55)
I've boost tested a number of FD's, the pressure usually does fade away after a few seconds, but it will build up pressure.
I usually set my air compressor to 20psi or so then feed air in.
That is a mystery. Is the car making boost in general?
Dale
I usually set my air compressor to 20psi or so then feed air in.
That is a mystery. Is the car making boost in general?
Dale
#5
Yea I set my compressor to 20 psi as well and am feeding the system via a tire valve. I am unable to build any pressure at all. I tried feeding air while turning the eccentric shaft to see if there was any position of the rotors that wouldn't leak all the air straight out but couldn't find one. Not convinced the pressure is even getting that far.
The stock twins boost great. I'm chasing down a boost control issue (sometimes on 3rd/4th gear pulls it spikes beyond what I've got it set for) so I thought maybe I had a vacuum leak in/around the wastegate actuator/solenoid which I was trying to find with the pressure testing in the first place.
The stock twins boost great. I'm chasing down a boost control issue (sometimes on 3rd/4th gear pulls it spikes beyond what I've got it set for) so I thought maybe I had a vacuum leak in/around the wastegate actuator/solenoid which I was trying to find with the pressure testing in the first place.
#6
RX-7 Bad Ass
iTrader: (55)
Where are you piping in the air pressure, and where are you reading boost from? If one or either is after the throttle plates, that could be blocking the pressure. Open the throttle plates up during the boost test.
Dale
Dale
#7
At first I tried introducing air through one of the top nipples (where my BOV is normally sourced from) on the UIM. Then I tried on the other side of the throttle at the y-pipe. I also opened and closed the throttle by hand and nothing seemed to make any difference.
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trickster
2nd Generation Specific (1986-1992)
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07-01-23 04:40 PM