NoPistons -Mazda Rx7 & Rx8 Rotary Forum

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-   3rd Generation Specific (https://www.nopistons.com/3rd-generation-specific-18/)
-   -   7 - 5 - 2 Boost Pattern (https://www.nopistons.com/3rd-generation-specific-18/7-5-2-boost-pattern-29588/)

jonrx7uk 12-02-2003 08:36 AM

'92 Jap import 3rg Gen RX7.

Had the car a month or so and fitted a boost guage yesterday, and got a 7 - 5 - 2 Boost Pattern. Now i know why the car doesn't feel too fast https://www.nopistons.com/forums/pub..._DIR#>/sad.png



The car has twin K&N filters and a downpipe (i think). Everything else looks stock. I have replaced the inlet extension manifold gaskets recently but was wondering what else to look for which would indicate the crappy boost pattern.



I am new to the rotary world but have had my head under the bonnet (hood!) more than behind the wheel.



Blocked main cat? If so, is it okay to replace and will i need to alter the ECU?



Any help much appreciated.



(the forums in the UK are a bit crap.... https://www.nopistons.com/forums/pub...IR )

amp 12-02-2003 09:54 AM

you need to generate 8psi for the secondaries to properly boost..

check the double throttle..make sure thats not stickin

check the coupler for the ypipe..make sure theres no leak there

check your precontrol solenoid..

rsjetjock 12-02-2003 10:04 AM

You are having a typical problem for an FD.

Before looking into solenoids and throttles bodies, check all hoses from the turbo outlet to the intake inlet. 98% of the time it is a small crack in a hose. Inspect them very carefully. When the line is not under boost it can be had to find.



If you determine that it is not a crack in a hose. Then move to the turbos solenoid controls.

9BASE3 12-02-2003 10:46 AM

Yup. Do the above and you should find the problem.. https://www.nopistons.com/forums/pub...#>/biggrin.png





Oh, welcome by the way!! Stick around!

apexkw 12-02-2003 10:57 AM

good info above. my problem was the hose going to the bottom of the intercooler was cracked. next one was the hose coupler on the y pipe..and some rotten vacuum lines.

jonrx7uk 12-03-2003 02:37 AM

Checked all the inlet hoses (1 to CRV, 1 to Bypass) and they had tiny cracks where the hoses joined the turbo assembly. Cut the hoses down and reinstalled them, no difference https://www.nopistons.com/forums/pub..._DIR#>/sad.png



Checked the 'Y' pipe coupler, no problem there...



Checked all vacuum hoses in Rats nest.



Disabled the double throttle last week.



Will check the hose to the bottom of the intercooler and the vac line to the vacuum chamber tonight.... Will let you know.



I checked a few previous threads and thought that the 2 solenoids behind the pressure chamber may have been swapped round, so i swapped them and took the car out for a run. It ran rough at idle but made a solid 5 psi to redline. By doing that am i disabling the ECU control of the 2nd turbo?



How do i check the function of the solenoids?





Many thanks

Fd3BOOST 12-03-2003 08:39 PM

God I thought I would never see a "I have a 3-6-8 boost pattern what do i do" thread.





Anyway sounds like you are not getting any secondary boost. You need to at least ins[pect the charge relief valve and the large black hose that connects it to the Y pipe assmebly. The charge control valve might also be sticking.

Look into anything controlling secondary boost..



http://www.fd3boost.com/Images/Techn...inal_image.jpg

amp 12-04-2003 08:17 AM


Originally Posted by Fd3BOOST' date='Dec 3 2003, 09:39 PM
Look into anything controlling secondary boost..

but hes not generating enough psi on the primaries for proper transition to the secondaries...

which is regulated by the precontrol solenoid..

are we dealin with factory vacuum lines here jon...

Fd3BOOST 12-04-2003 12:55 PM


Originally Posted by amp' date='Dec 4 2003, 06:17 AM
but hes not generating enough psi on the primaries for proper transition to the secondaries...

which is regulated by the precontrol solenoid..

are we dealin with factory vacuum lines here jon...

Possibly but I have had problems with the hose I mentioned and it caused similar boost problems. ie 7-8 on primary then a even worse secondary.

He is still getting transition as his boost pattern clearly shows.

jonrx7uk 12-05-2003 04:06 AM

i am running on factory / aftermarket vacuum lines (some are blue).



Boost guage shows 17hg at idle which i assume is normal.



I have visually checked the charge relief valve and the large black hose that connects it to the Y pipe assemebly (1 inch diameter), and cut a small crack out with no difference. Can i check the CRV by swapping it with the ABP valve to see if there is a difference? The ABP valve is dumping boost when i let off...



I replaced the inlet hose to the primary turbo with a new pipe (from a 200SX) last night, thinking that it may be deforming under boost, no difference...



Put new hose clips on all the 1 inch pipes, no difference...



Checked all pipes to and from Intercooler...



Visually inspected primary turbo, no noticable play in shaft...



Is it time to go non sequential?


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