Strange Boost Pattern And Late Transition
12-02-2002, 08:41 AM
#1
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Join Date: Oct 2002
Posts: 113
I started asking about this in another thread where I thought the problem was the precontrol, but I think I've ruled that out now.
Here's what I get at WOT in 3rd
0-5500 rpm: boost steadily decreasing from 13psi to 10psi
5500 rpm: 5 psi
5500 rpm-redline: 6psi
With the high initial boost, I'm thinking that the wastegate or charge relief might be the problem. The low secondary could be just a leak somewhere, but the late transition is very confusing. Anyone experience a similar problem? Any suggestions would be much appreciated. Thanks.
(my mods: intake, smic, cb)
Here's what I get at WOT in 3rd
0-5500 rpm: boost steadily decreasing from 13psi to 10psi
5500 rpm: 5 psi
5500 rpm-redline: 6psi
With the high initial boost, I'm thinking that the wastegate or charge relief might be the problem. The low secondary could be just a leak somewhere, but the late transition is very confusing. Anyone experience a similar problem? Any suggestions would be much appreciated. Thanks.
(my mods: intake, smic, cb)
12-02-2002, 09:25 AM
#3
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Join Date: Oct 2002
Posts: 113
I don't hear any leaks (but that doesn't mean there aren't any). The y-pipe and coupler is stock. The efini is on order. I had a pretty good look at the y-pipe coupler when I was debugging the precontrol, and it seemed ok; no huge holes like some people report.
Why do you say to check the CRV? Because of the high primary or because of the low secondary?
Why do you say to check the CRV? Because of the high primary or because of the low secondary?
12-02-2002, 09:33 AM
#4
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Join Date: Feb 2002
Location: Frederick MD
Posts: 6,331
The low secondary. I have never had a problem with this, but some people say that it will cause low secondary boost if not functioning properly.
You can always swap the BOV and CRV to see if that fixes the problem... Then you'll know if the CRV is bad. Both valves are the same, just used differently. (Can someone verify this?)
You can always swap the BOV and CRV to see if that fixes the problem... Then you'll know if the CRV is bad. Both valves are the same, just used differently. (Can someone verify this?)
12-02-2002, 09:59 AM
#5
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Join Date: Oct 2002
Posts: 113
Here's a hypothesis. Can anyone agree with this or explain why I might be full of sht...
The primary boost decreases before transition because the precontrol is gradually bleeding off more exhaust to the secondary (as it should). But the wastegate, which should (I guess) opposite from the precontrol to keep the boost constant over this region, is not working. i.e., the wastegate should gradually close and the precontrol should gradually open, thereby keeping the primary boost pretty constant, exept that maybe my wastegate is not working so my boost starts out too high and decreases.
This is just a theory, but if there's some reason it couldn't be true I'd like to know so I don't waste time checking it out.
And it still doesn't explain the late transition. That's the most confusing part of this whole problem.
The primary boost decreases before transition because the precontrol is gradually bleeding off more exhaust to the secondary (as it should). But the wastegate, which should (I guess) opposite from the precontrol to keep the boost constant over this region, is not working. i.e., the wastegate should gradually close and the precontrol should gradually open, thereby keeping the primary boost pretty constant, exept that maybe my wastegate is not working so my boost starts out too high and decreases.
This is just a theory, but if there's some reason it couldn't be true I'd like to know so I don't waste time checking it out.
And it still doesn't explain the late transition. That's the most confusing part of this whole problem.
12-02-2002, 02:16 PM
#10
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Join Date: Oct 2002
Posts: 113
I just read on the FAQs at
http://www.autosportracetech.com/RX-7/rx7stuff.htm
that my boost gauge might read several psi (3-4psi by my calculations) higher because I live at 7000ft above see level. However, I'm not sure if I completely understand this since the gauge reads very close to 0psi when the car is off. Maybe the gauge automatically complensates.
Anyone have any experience with boost at high altitude?
Does the ecu (and mine is stock) regulate the pressure to be 10psi above sea level or 10psi above the measured atmospheric pressure?
http://www.autosportracetech.com/RX-7/rx7stuff.htm
that my boost gauge might read several psi (3-4psi by my calculations) higher because I live at 7000ft above see level. However, I'm not sure if I completely understand this since the gauge reads very close to 0psi when the car is off. Maybe the gauge automatically complensates.
Anyone have any experience with boost at high altitude?
Does the ecu (and mine is stock) regulate the pressure to be 10psi above sea level or 10psi above the measured atmospheric pressure?