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boost problems ????


Alex Cavaliere
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Hello I drive a Subaru Impreza Turbo EDM MY98 with plug in Link ECU V4 road Turbo = TD05-16G big (stock TD04-13T) Injector= stock 380 cc fuel pump = walbro 255 lt The Boost in 3th Gear is: 1.3 bar @ 4600 RPM 1.2 bar @ 5100 RPM 1.1 bar @ 5400 RPM 1.0 bar @ 5500 RPM 0.9 bar @ 5600 RPM 0.8 bar @ 6000 RPM 0.7 bar @ 6400 RPM 0.65 bar @ 6900 RPM the car is not competitve with this boost process now i found in a loggin make with link software something strange: the zone are just to 5500 RPM 550, the next step 5600 RPM the zone are 475 just when the boost loss 5700 zone = 480 so further to red line. have you a idea ??? wath can cause this problem ???? thanks for answers alex www.impreza-cup.ch

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OK, there are two things to consider here:

  1. Can your turbo produce the boost that you want all the way up through the RPM?  Are you sure that it is not running out of puff?  Dont just assume, you must test this.
  2. Boost control is not set up properly.  You should enter the boost target values that you want in the boost targets part of the zone table.  For the area where it is coming on to boost, enter targets that are close to what it can actually make.  that will help prevent overshoot.  Make sure your base, and sensitivity values are setup correctly.

Note that to run high boost you may need to upgrade your MAP sensor.  Otherwise you may go outside its range...

The zones you are talking about, are they the fuel zones?

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hello Ashley thanks for answers yes the turbo can produce boost just to red line. boost control i make with manual boost controller perrin, also with apexi AVCR selenoid and Apexi Controller and i try without hose to waste gate. it is always the same. you recommend the stock map sensor just to 240 Kpa, i dont exceed this boost. the zone is CRNum 1106 from Data Logging i think is ignition zone not fuel but im not sure. with big turbo it make so: RPM MAP Zone (1106) 5300 218 550 5500 209 550 5600 202 475 5700 197 475 5900 191 475 6000 189 480 6100 184 480 ... ... whit smaller Turbo TD04 its the same but later RPM MAP Zone (1106) 5900 207 560 6100 205 560 6300 204 480 6300 200 480 6400 198 485 thanks Alex

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CRN 1106 is "Active Zone"  It tells you what zone is currently being used in the fuel and ignition tables.  It does not tell you the value of fuel or ignition.  It also has nothing to do with boost control.  What are the target values in the boost table?  If the boost targets are getting smaller then the actual boost value will also get smaller...

the only thing weird about the logs is the funny zone numbers you have given...  The first digit in the zone number refers to the table row while the last two digits refer to RPM.  So you can see the row number going down with boost (from 5 to 4), but the last two digits do not track the actual RPM (RPM is increasing, but active zone is going really high!!!

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yes i found this also weird mine car d`ont can turn 8000 RPM or more. In mine zone table it does not have zone 480 or 485 the max. in row 4 are 475 and with big Turbo i become zone 480 by 5600 RPM now i fit the stock ECU and in the next days i go to a Subaru Dealer for make a check with Subaru Select Monitor perhaps finde these something not in order thanks Alex

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  • 3 months later...

I think you need to get a tuner to look at your car.  If you are running out of injector duty cycle then you engine will be going lean!!!  It probably isn't the reason your boost is dropping off.  That could be a boost control issue or a turbo matching issue.  You will obviously need to install bigger injectors ans re-tune your engine.  At minimum, put a wideband O2 sensor in and check you mixture at full power in case you are doing damage to your engine.  I think bore washing is the least of your worries if you have injectors at 100%.  I am not sure why you saw 85% on the ECU and 100% on the Apexi doo dah!!!

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