overboost problem, need a little help

A

at7we2

Member
Joined
Oct 31, 2003
I recently installed an aftermarket boost controller on my GN. I didn't like the unit so I removed it and returned to the OEM setup. Ever since I reinstalled the factory solenoid and "Y" fitting I have *no* boost control. At about 2/3 throttle the boost shoots past 24 psi. :eek:

I've got the restricted side of the "Y" fitting going to the compressor tap and I've already replaced all of the hoses with new hose and I've replaced the solenoid with a brand new GM wastegate solenoid - still can't turn the boost down. I've adjusted the rod way-way out, much farther out than I ever had to before and still get 24+ lbs. of boost. If I bypass the wastegate solenoid by running a hose straight from the compressor to the actuator it works fine. I have full adjustability and there's no problem. That means the actuator and wastegate are working properly, right? So what could be wrong with the factory setup? Is there anyway to check the signal to the solenoid? Is there anything else I can check?

any input is appreciated.
 
still have same problem

come on guys, 66 views as of 12/3 and no replies? I've still got the same problem I described in my first post.

How can I check the signal to the wastegate solenoid?

Thanks,
Rob
 
Did you replace the hoses with the kit or your own from the auto parts store? The one going to the solenoid is 5/32 as the others are 7/32. It matters too as the 7/32 used for all three will leak at the valve even with a zip tie sometimes. The OEM set up is stepped down at the valve with a plastic L fitting and smaller hose.
 
I was having trouble with mine. But. it was spiking to almost 30. Installed one of Jason's Boost controllers, and now a solid 20.

Still can't figure out why it started doing the spiking.
 
Russ,

I'll check the hose sizes, but I'm pretty sure everything is tight. I used some of what the boost controller came with although I'm still using the factory "L" fitting at the solenoid with the original smaller dia. hose. Any other ideas?

Bruce,

I'm sure if I let it go, it would probably hit 30 psi or close to it. I've seen it hit nearly 27 with the Scanmaster and knock gauge going berzerk! :eek: :eek:

Thanks for your replys, but I'm still open for suggestions. :confused:

thanks,
Rob
 
The restriction hole does not go to the compressor housing. Put it going to the accuator side. ;)
 
I'm 99% sure about my last post, but if that does not work, then putting the metered oriface going to the solonoid would surely make more pressure go to the accuator to open the wastegate sooner.

Scott
 
Well, I see the info on gnttype, in a few different places. Maybe they are right, but the suggestions I gave will make more pressure to the accuator to open WG sooner. What type of DP do you have? Here is a test to try:
Turn on ign. (key on, motor off), pop hood, open throttle body (WOT), listen for solonoid to click fast, or make noise. Here it? Then that works ok then.
Take off the accuator arm, check for free movement in the wastegate valve. AT* DP often get stuck. another thing to test is the diaphram in the accuator. Take off line going to it, blow into it. Is accuator sealed? Do the same thing for the solonoid. It should be closed and not allow air to pass through it when car is idling. Find anything?

What type of boost cont. did you try?
 
turbo2nr,

*IT WORKED*!!!! Woooo--hoooo!!! :D :D


you were right, putting the orifice toward the actuator instead of the compressor works perfectly!!! I feel stupid for not trying that myself first! :p wonder why gnttype.org shows it the other way? :confused:

Thanks for your help!

Rob
Dallas, Tx
 
hmm, I have always went by the saying" the straight side of the 'y' fitting goes straight to the turbo", which is how it is shown on gnttype.org, and is the way it is on my untouched TTA.
I'll have to try switching it around as well since I'm having some boost controll issues and using the BstC controller with some new turbos when set at lower boost settings below 20#.
 
I just looked on my car. It has the straight end going to solonoid, the other side of the (I'm going to call it a "Y" because that's what it looks like) has two outlets, the straight end goes to the compressor, the angled end goes to the accuator. I think the angled end has the oriface, right? I'll go check.
 
Originally posted by turbo2nr
I just looked on my car. It has the straight end going to solonoid, the other side of the (I'm going to call it a "Y" because that's what it looks like) has two outlets, the straight end goes to the compressor, the angled end goes to the accuator. I think the angled end has the oriface, right? I'll go check.
Click to expand...

Look on the gnttype page here at the bottom, there is a diagram, which is in agreement to what I've always thought (not sure which one of the 'Y' arms has the restrictor in it).
http://www.gnttype.org/maint/quickref.html

But what Rob above and I thought you were saying to to switch the "Arms" of the "y' between the actuator and the compressor...the solenoid always should be connected to the single bottom part of the "Y".
 
turbo actuator hose "Y"

yeah, I've always had the single, bottom of the "Y" going to the solenoid. It was the other legs I had to swap. As a side note, my plastic "Y" fitting is grey instead of black like in the illustration on gnttype.org. Is it possible the orifice is in a different location on the black an grey fittings? I can't go look at it right now, and I don't remember which "leg" has the orifice (straight or side) on my car. I'll check again later.

Either way, I had the restriction to the compressor as shown in the diagram and it didn't work, *at all*. Now that I've filpped it, putting the restriction to the actuator, everything is working perfectly.

and thanks again for helping me figure this out and taking the time to look at your cars.

Rob
 
I've got a couple of extra 'Y' fittings and the ones I have are gray and the restrictor orifice is in the straight leg of the 'Y' so if putting it to the actuator is working for you now, that is opposite of what is on gnttype.org and is dirrent then the way mine has always been hooked up, and it worked fine with the stock turbo....but I am having problems now at lower boost levels so I'll swap them around and try it.

But thinking about it, with the restrictor in the leg going to the compressor housing, that will restrict the full boost pressure from going to the solenoid and the actuator, if you change that now to be on the actuator side, its only restricting the full boost pressure from going to the actuator, full pressure will be on the solenoid now.....that just doesn't seem right since all the solenoid does is bleed off pressure going to the actuator...guess I'll try it and see what happens.

BTW, I've never seen a black 'Y' fitting either, the orignal on the GN 13 years ago and the original on my TTA were both gray, I'm fairly certain they were the originals on both cars as the TTA only has 5k miles on it when I got it.
 
Ok....I pulled the grey plastic "Y" fitting off my GN and I've got it in my hand now. The brass orifice is in the *straight* side of the "Y". I had the straight side with the restriction going to the actuator and everything worked fine. However, when I had the restriction going to the compressor (like the illustration on gnttype shows, I had no boost control (boost just kept climbing, FAST!).

so do I have some kind of freak actuator or solenoid? :p

Rob
 
Just FYI, I finally solved my slow boost creep problem. Switching the hoses off of the "Y" did not have any effect.
Mine would start off at the set boost level, but would slowly creep up to 20-21# before it would stop creeping.

I ended up taking the exhaust housing off, ( I have a 3" THDP) and the WG hole was already opened up to 1 1/16", I ended up opening it up to about 1 3/16" and fully ported and put a smooth radius curve in the inside of the housing around the WG hole so exhaust gas can flow easily out of the hole.
Works like a charm now.
 
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