Fitted a decat, boost drops??

jimmy180sx

Fitted a decat to my subaru impreza after the NCT, as since doing so the boost has dropped to about 0.5bar from 0.9. Any ideas?

biko

Did you do it yourself or a pro?
Up down pipes?
Year/turbo etc?

jimmy180sx

biko wrote: »

Did you do it yourself or a pro?
Up down pipes?
Year/turbo etc?

Fitted it myself. All new gaskest and checked for leaks etc.

Its a decat down pipe. The car is a 98 UK turbo 2000 impreza totally standard except for HKS induction and full turbo back stainless system including the newly fitted decat.

jimgoose

Presumably this includes a hi-flo air filter of some kind as well? You'll need an ECU re-map to compensate for the change in gasflow. This would probably explain the lower boot level as well.

jimmy180sx

Would an adjustable actuator or boost controller rectify this? I dont wont to be running anything above standard boost of 0.9bar. Just would like that extra bit of power up the rev range, as it is noticable different to when i had the standard cat on it. Standard cat seemed to run that bit smoother.

jimgoose

jimmy180sx wrote: »

Would an adjustable actuator or boost controller rectify this? I dont wont to be running anything above standard boost of 0.9bar. Just would like that extra bit of power up the rev range, as it is noticable different to when i had the standard cat on it. Standard cat seemed to run that bit smoother.

The computer should be optimising the boost itself, I should say. It's probably concluding, based on sensor data, that less boost is needed because of the increased flow-volume in there. I can't tell you any more - you need a serious Scooby-Doo nerd to take it from here, either on here or in one of them performance shops.

jimmy180sx

jimgoose wrote: »

The computer should be optimising the boost itself, I should say. It's probably concluding, based on sensor data, that less boost is needed because of the increased flow-volume in there. I can't tell you any more - you need a serious Scooby-Doo nerd to take it from here, either on here or in one of them performance shops.

Cheers Mr.Goose

dan_ep82

Check for leaks around the turbo/actuator vac lines.

Also check the actuator is controlling the boost. Easiest way is to pull the pipe off that goes from the actuator to the turbo.

Bring it for a very careful drive,no flooring it. Reason being you should have unlimited boost,if it still wont go over .5 there's something wrong with the actuator. Try freeing oil on the arm.

Also take the actuator arm off the wastegate flap and try moving the flap by hand.sometimes aftermarket decats can interfere with the wastegate penny.

Usually fitting a decat increases the boost,you hardly hit fuel cut and knocked it into limp mode? (not even sure if the wrx has limp mode)

Also you can post a thread here,you'll get an answer fairly quick - http://www.isdc.ie/

12gauge dave

Is it idling higher than it used to?
Maybe your actuator isnt up to the task anymore. Can you get upgraded ones for imprezas?

Was the decat new or used ever been welded or anything?

jimmy180sx

dan_ep82 wrote: »

Check for leaks around the turbo/actuator vac lines.

Also check the actuator is controlling the boost. Easiest way is to pull the pipe off that goes from the actuator to the turbo.

Bring it for a very careful drive,no flooring it. Reason being you should have unlimited boost,if it still wont go over .5 there's something wrong with the actuator. Try freeing oil on the arm.

Also take the actuator arm off the wastegate flap and try moving the flap by hand.sometimes aftermarket decats can interfere with the wastegate penny.

Usually fitting a decat increases the boost,you hardly hit fuel cut and knocked it into limp mode? (not even sure if the wrx has limp mode)

Also you can post a thread here,you'll get an answer fairly quick - http://www.isdc.ie/

Cheers dan i'll give it a go. DecT is second hand but in very good condition, no welds, etc.

I'll let you know if successful

jimmy180sx

So after a lot of routing and digging i couldnt find any leaks. A friend suggest i check for any fault codes, which i did and guess what, map sensor fault. I never even seen the check engine light turn on. I tested the sensor and it is fecked. Replaced it with another from my donor and reset ecu, and wahay, loads of boost.

Cheers for the help people

jimgoose

jimmy180sx wrote: »

So after a lot of routing and digging i couldnt find any leaks. A friend suggest i check for any fault codes, which i did and guess what, map sensor fault. I never even seen the check engine light turn on. I tested the sensor and it is fecked. Replaced it with another from my donor and reset ecu, and wahay, loads of boost.

Cheers for the help people

Jolly good. Well fixed, that man. :cool: