Boosting Problem? Not Wastegate...

[ZeroZ95TSI]

I have a 1990 eclipse GSX. All stock. Now this is kinda both ways... i have a boost problem meaning my boost is unlimited like my wastegate is stuck but its not because ive checked it. im using the stock BCS and its not working i guess... i disconnected the battery, resetting the ecu in the process and it works... i have to do this everytime i shut off my car in order for my boost to stay at 10 psi. Whats the problem here... bad ECU? that would suck... i could just get a manual boost controller but... but... i wanna know where the problem lies first. HELP ME

 

[CanadianTSi]

Run a pressure source straight to the wastegate and see what happens. It should bring your boost down to around 8psi.

 

[ZeroZ95TSI]

I have another question.... what does that have anything to do with it... its not a wastegate problem... its a boost controll issue through the ECU. Im just wondering if i need to get a new ECU or what... thanks for trying though

 

[Cool Mr Steve]

Can I ask why your still using the BCS? You have a MBC, so the BCS is not necessary. Most people completely bypass the BCS when using an MBC because it could cause problems with inconsistent boost. It's sort of redundant to have another boost controller, and can really only cause more issues.

 

[Newlogics]

ECU can't really control boost. It can activate BCS and raise boost by a couple of pounds, but that's it. Your ECU has NOTHING to do with your boost issue. Your BCS may be clogged or broken. Get rid of it, and make sure MBC is hooke right.

Routing a vacuum line from pressure source directly into the wastegate will bring your boost to about 8psi REGARDLES (provided wastegate actuator works) of BCS or your imaginary ECU boost control problem.

 

[Ultimatedsm]

Get a MBC, hook the arrow side to the wastegate actuator, and the other side to the J-pipe nipple, I don't recommend tapping the BOV line, I noticed boost response wasn't as great.

 

[oldman]

you're getting infinite boost because the bcs is bleeding off pressure before it even gets to the mbc, remove your bcs completely, cap off the return nipple near the MAS, J-pipe fitting goes directly to the inlet of the mbc, outlet of the mbc goes directly to the actuator. The Canadian is right, don't tap your bov line for your mbc.

 

[ZeroZ95TSI]

i didnt say that i had a manual boost controller installed... i have the stock bcs... the whole car is set up stock besides for BOV and emissions. i have replaced the bcs many of times and its the same. im going to get a manual boost controller soon i was just wondering if the bcs gets controlled by the ecu. i know theres no point in using two boost controllers at the same time i never said i had a manual boost controller installed. thanks though

 

[ZeroZ95TSI]

heres the key information. my boost is unlimited becuase wastegate is stuck closed because the bcs is staying closed and thus not letting any pressure to the line to open the wastegate. My bcs is controlled by the ECU. !!!When I UnHook My Battery And Plug It Back In Then My Stock BCS Works Fine!!! I know i need to get a manual boost controller im just planning on selling this one and i wanna be able to keep the stock BCS on.

 

[oldman]

Are you sure you didn't change the original hose routing? The factory BCS doesn't work like you think it does. Pressure doesn't pass through the bcs on it's way to the actuator, bcs is simply a bleeder valve bleeding pressure off the hose from compressor to actuator and reroutes back to the intake pipe. If anything, the bcs is stuck open bleeding off too much pressure causing infinite boost.

 

[Newlogics]

Like Oldman said (and oldmen should be listened to), most likely there is a vacuum routing problem.

Stock BCS has two positions: Closed and open (duh)
When closed, 100% or pressure is routed into the wastegate actuator and pops it open at around 8psi.
When open, it bleeds some of the pressure from the line, thus taking longer to open wastegate actuator and raising boost to around 11psi.

Let's say your BCS is hooke up to be 'in line' with your wastegate actuator, instead of as a bleeder. When you reset your ECU, ECU will open BCS (as default position), which will allow pressure to get to wastegate actuator and thus controlling your boost. Then ECU sees some knock (common for 1Gs) and closes BCS. All of a sudden your line to the actuator is blocked and your boost is no controlled.

This scenario fits what you're describing, so all I can conclude from this, is that your BCS is not hooked up as a bleeder (the proper way), but instead is in-line with actuator.

hope this makes sense.