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Quick Boost (PSI) Question


Fresh802
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Alright, so i have a 1989 chrysler conquest tsi. i hear that you should be boosting 7psi until around 4k rpm. And then 10psi after that. Mine does the exact opposite. so i get 10psi at lower rpms but then it drops to 7psi after 4k. My idle is high also around 1500. sometimes it idles around 1000 but usually 1500. Any help would be greatly appreciated. is there a way to make it just run 10psi all the time? Im not sure how the wastegate works on this car, any other car i would have just installed a boost controller and been done with it. But I am wondering also how the car goes about a 2 step boost setup. thanks!

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It sounds like for your idle issues you need to do a tps / isc reset. Just take a look at the service manual (you can get it at starquestgarage.com) and follow the instructions to reset everything correctly. As far as your boost issue is concerned it sounds like your vacuum sources for the wastegate are just switched around. The 88-89 cars have a 3 port wastegate, one is a reference port, one is for 7psi, and the last for 10psi. Just do a quick search on the forums and you will find the solution to making it always run 10psi.

 

Allen

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It sounds like for your idle issues you need to do a tps / isc reset. Just take a look at the service manual (you can get it at starquestgarage.com) and follow the instructions to reset everything correctly. As far as your boost issue is concerned it sounds like your vacuum sources for the wastegate are just switched around. The 88-89 cars have a 3 port wastegate, one is a reference port, one is for 7psi, and the last for 10psi. Just do a quick search on the forums and you will find the solution to making it always run 10psi.

 

Allen

Thank you very very much! Well, I just gave a good hard search on the whole 10psi thing. Couldnt find anything. But Ill put my car in the garage tonight and reset the tps/isc. I appreciate it very much. If you have any direct info on the 10psi thing let me know, or if you find anything referring to it. -thanks!
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After doing a bit of reading it looks like you should leave the middle port (middle of the actuator) open to the air, then use either of the outer ports for your vacuum source, then cap the other outer one you didn't use. That should set you up to always run 10psi.
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How could i not find that? haha. Seems simple enough. Ill give it a go on saturday. I would just like to say, I am on miata forums too and the help ive gotten here in one day has been better than the help ive had in a year on the miata forums. haah. and for that, i thank you.
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Given that Turbine Inlet Pressure (TIP) goes up exponentially with boost pressure consider that you may be making more power at 7 psi above 4K. A dyno would (dis)prove it.

I 100% understand what you are saying, But you can really tell the difference in power when its drops from 10 to 7.
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After doing a bit of reading it looks like you should leave the middle port (middle of the actuator) open to the air, then use either of the outer ports for your vacuum source, then cap the other outer one you didn't use. That should set you up to always run 10psi.

My wastegate has 3 ports yes. but it seems that one is on top of the other? not positioned like this . . . more like this : .
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If I remember correctly, manual trans cars went from 7 to 10. Auto cars stayed at 10. The parts that controlled the switch can be swapped from car to car.

 

 

The actuator has a big end and a small end. The port on the small end is 7 psi (leave open). The 2 other ports are both 10 psi. You run a line to one of them and cap the other one.

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If I remember correctly, manual trans cars went from 7 to 10. Auto cars stayed at 10. The parts that controlled the switch can be swapped from car to car.

 

 

The actuator has a big end and a small end. The port on the small end is 7 psi (leave open). The 2 other ports are both 10 psi. You run a line to one of them and cap the other one.

Mine has 2 ports on the small part and 1 on the big part. 1 from the small end and one from the big end both go to a small black plastic piece that seems to connect to the airbox? while the other one connects directly to the plastic tubing that runs across the top of the valve cover.
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Figured it out. Only part im wondering now is what do i do with the little black plastic piece that 2 of the lines were attached to? it also has a electrical plug on it.

 

The ignitor controls the solenoid on the aircan that switches between 7 and 10 psi.

 

unplug it

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