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87.5 ea82t (ecu controlled wastegate actator) and manual boost controllers?


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13 replies to this topic

#1 87.5ea82txt

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Posted 04 January 2010 - 03:23 AM

Has anyone experimented with manual boost controllers on the later hotwire MAF ea82t engines? The ecu normally controls the wastegate actuator controller solenoid to either send a signal to the actuator from compressor pressure or pressure between the MAF and the compressor itself. One line runs from the solenoid to the compressor housing exit (Boost pressure), the other, to the intake boot (atmospheric pressure- or less than depending on how much cfm is currently being drawn from the compressor in relation to air filter restriction to create negative pressure in the intake). I have experimented with placing the mbc after the solenoid and even bypassing the solenoid entirely and have encountered the same results. The turbo seems to max out 17+ lbs! at even low throttle settings. Kinda makes it work like an on/off switch. The mbc is one that I made from brass fittings from the hardware store with spring and ball bearings and a 1/16" bleeder hole in the side to allow pressure to escape. I did not install it backwards. I even removed the spring and ball bearings so it was just a bleeder. No change. I figured it would run like stock except boost a little higher. I even taped over the bleeder to see if that would change anything. It didn't. Has anyone else encountered this?

Edited by 87.5ea82txt, 04 January 2010 - 03:29 AM.


#2 AWD TURBO!

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Posted 04 January 2010 - 03:46 AM

well the home made boost controller is junk :-\ but does work

#3 Turbone

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Posted 04 January 2010 - 08:15 AM

Theres a real good chance your going to blow your engine up using this (ask me how I know).
I got smart and bought a better unit off Ebay.
http://cgi.ebay.com/...=item518f85dcd4
The price I paid for mine is alot less, something like $60, I suggest looking at all the auctions for a cheaper deal.
http://motors.desc.s...s&_osacat=33739

#4 Gloyale

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Posted 04 January 2010 - 09:34 AM

The spring in your controller is too soft or something.

I have a mass produced version of the same controller on my rig, it works fine. I can tune from 6 psi all the way up to 14 with fine adjusment in hte middle.

If you are gonna use an MBC, just disconnect the wastegate solenoid (vac line only, pull hte elec. connectors and you get a CEL)

#5 Forkspear

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Posted 05 January 2010 - 02:10 AM

did you use a brass valve? or just some fittings with the spring inside. i used one designed for brass tubing. your spring is too stiff. too soft of a spring would just let all of the boost signal go through the controller and open the wastegat at 8psi. if the spring is too stiff it will act like the wastegat is not even hooked up and your boost will skyrocket with very little throttle like you said. try using a softer spring or trimming it down some. do not the stock boost controller hooked up if you have a controller. it will only mess things up. just unhook the lines from the turbo and wastegate and let them hang. you can unhook the one from the intake tube if you want but you will have to cap the hole it leaves. there is nothing wrong with a homemade boost controller. there is something wrong with asking $60 to $80 for a simple valve with a ball and spring with some fancy paint. with the controller gutted and all the way open you should run stock boost. if you are not something is wrong. try running just a vacuum hose from the turbo to the wastegate. it should run at 8psi. if it still skyrockets your actuator is probably toast

#6 Turbone

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Posted 05 January 2010 - 08:13 AM

This is what happened to my last EA82T after using a brass type MBC.
It didnt matter how much I tried to get it right, it still sucked and ruined my engine. If you want to take the chance of this happening, keep using the homemade stuff. Please post pics of the results.
Posted Image

#7 Gloyale

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Posted 05 January 2010 - 12:29 PM

did you use a brass valve? or just some fittings with the spring inside. i used one designed for brass tubing. your spring is too stiff. too soft of a spring would just let all of the boost signal go through the controller and open the wastegat at 8psi. if the spring is too stiff it will act like the wastegat is not even hooked up and your boost will skyrocket with very little throttle like you said.


You got it backwards. The MBC is suppose to bleed off pressure from the wastegate line. NOT bleed pressure THROUGH

If installed properly, a MBC with a weak spring will bleed ALL THE PRESSURE out of the WASTGATE line, leaving no pressure to open the wastegate, and Overboosting the intake.

IF the spring is stiff, no pressure will bleed from the wastegate line, so it will actuate a the stock 6-7 PSi

#8 87.5ea82txt

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Posted 05 January 2010 - 11:49 PM

So with the bleed through to the wastegate design, the wastegate actuator is going to see no signal until the boost pressure rises enough to lift the ball off the seat, which explains the high boost pressure at low throttle and the huge boost spike.
With the bleed to the atmosphere setup, one would run a line from the compressor to the wastegate actuator and put a T with the mbc somewhere in between the two. Then lessen the tension on the spring until the boost pressure in the line overcomes the spring tension and lifts the ball off the seat, venting pressure to the atmosphere and increasing boost pressure.

So this works pretty good? How does the stock computer control setup compare to the mbc venting to the atmosphere set at the stock boost level? Does the computer modified solenoid work some extra torque in there on spool up or is it pretty comparable?
As far as I know the engine has 105k miles on it and has never been pulled apart in its 23 years. I figure 10psi should be pretty safe with an intercooler, high flow intake, and for an exhaust, it ends after the cat, which is hollowed out. I've got an msd coil and I gapped my plugs a tad wider if that makes a difference.

I briefly played with mbc and took it off after the way it ran. I just recently rotated the compressor housing about 20 degrees or so to better line up with the angle of the intake of the intercooler. When doing so, I marked the wastegate actuator in its original position, rotated it, and drilled a new hole on the bracket to bolt it up. I've only driven the car a few times down the road and back to see how she ran and it wants to boost around 12psi...so really, decreasing boost is the problem now. I was just curious what the deal with the mbc was. I'm thinking the actuator is sitting a little further away now and the extra spring pressure is holding shut the wastegate. I'm going to try and widen the hole and rotate the actator about 1mm closer and see if that lowers it down some. Or what if I just bypass the solenoid and hook the compressor strait to the actuator and see if that lowers it at all. If thats the case, then I may not need a mbc or computer control at all.

Edited by 87.5ea82txt, 06 January 2010 - 03:02 AM.
Updated


#9 87.5ea82txt

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Posted 06 January 2010 - 02:24 AM

This is where I drilled the new hole.

[IMG]http://i879.photobucket.com/albums/ab357/875ea82txt/Image172.jpg[/IMG]

Edited by 87.5ea82txt, 06 January 2010 - 02:45 AM.


#10 TheSubaruJunkie

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Posted 06 January 2010 - 02:56 AM

Do yourself a favor and get a REAL MBC... not some $10 home made piece of crap.

I tried the home made piece of crap once, and nearly destroyed my engine. Boost was never steady and fluctuated between 8psi & 12psi alot.

I then went to ebay and bought a much nicer MBC made by Go Fast Bits... and it worked 1000x better.

Believe me (and Rob.. & everyone else who tells you) boost control is not the place to cut corners or go cheap on. Do it right, or plan on doing it over again.

#11 87.5ea82txt

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Posted 06 January 2010 - 04:06 AM

Boost was never steady and fluctuated between 8psi & 12psi alot.


Another reason I question the reliability of the homemade controller to keep a particular amount of bleed or the amout of boost spike at a given boost pressure is I have no idea as to the spring rate of the homemade unit compared to one of the massed produced variety.

Right now I need to figure out my situation with the wastegate actuator and get my boost down to a reasonable level before I mess with something that's going to increase it. If it's because my hole is off, it can't be much.

#12 Forkspear

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Posted 08 January 2010 - 02:25 AM

Do yourself a favor and get a REAL MBC... not some $10 home made piece of crap.

I tried the home made piece of crap once, and nearly destroyed my engine. Boost was never steady and fluctuated between 8psi & 12psi alot.


my $10 piece of crap is quite nice. zero fluctuation. you just have to know what you are doing. i got fluctuation when i had no bleeder hole or ball and spring, just a brass valve. basically you adjust the valve to the desired boost spike then it drops back to stock. it just lengthens the time it takes the wastegate to receive the boost signal by restricting it. add a ball and spring in the valve and the signal cannot pass through to the wastegate until it overcomes the pressure of the spring. this pressure is easily adjustable with the valve. the turbo spools faster like this but boost still falls. you have to drill a tiny hole somewhere on the wastegate side of the valve. this does not let the pressure build up after the valve and open the wastegate. i can adjust my valve anywhere from stock to upwards of 14psi. my boost is rock steady. the size of the bleeder hole is relative to the size of wastegate line. when i swapped to the td04 the bleeder hole was too big for the smaller wastegate lines. i got creative and closed the hole up a little and it works fine. still rock solid right where i want it.

This is what happened to my last EA82T after using a brass type MBC.
It didnt matter how much I tried to get it right, it still sucked and ruined my engine. If you want to take the chance of this happening, keep using the homemade stuff. Please post pics of the results.
Posted Image


lol being new to turbo cars i accomplished that very quickly when i first got my rx. my buddy talked me into pulling off the wastegate line for a little while. needless to say it does not take much

#13 Forkspear

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Posted 08 January 2010 - 02:35 AM

Right now I need to figure out my situation with the wastegate actuator and get my boost down to a reasonable level before I mess with something that's going to increase it. If it's because my hole is off, it can't be much.


im sure you will figure it out. i would try moving the actuator so the rod is more parallel with the turbo. i know it has some angle built into it. moving the actuator down would shorten the rod and put less tension on the spring. looking at your picture, you might be able to use the original holes.

#14 Forkspear

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Posted 08 January 2010 - 03:20 AM

if you hook up the wastegate direct you should get 8psi. if its maxing at 17 psi with your controller you should make the spring softer
if it is setup to limit the signal. stiffen it if it limits pressure bleed. another thing to think about is if your actuator is messed up and running 12 by itself, fix it and you would probably run less boost with the controller set up the way it is.




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