weird problem with boosting
 

I have done the seq. simplification and all good solenoids for the turbo control, and both turbos work wonderfully. However, everytime I do a hard pull up to redline, then the next hard pull, the first turbo would not come on until I let the car cruise for about 10 seconds without boosting, then everything works wonderful again. But if I boost again after the last hard pull, the exhaust tone will be different, and I will not get primary boost at all, then after transition, both turbo will come on full boost. Can anyone tell me why this is occuring?

Since you have simplified the sequential setup, this may not apply. However, in the stock setup:

Once the turbos have both come on line (~4500 rpm), they will stay in parallel mode until the revs drop below 3000, at which time they will go back to sequential. Therefore, if you have the secondary turbo come on line, and then shift into the next gear and see above 3000 but less than ~5000 rpm, the turbo response will be slow and the exhaust note will be loud, since the exhaust path thru both turbos is open.

Does this sound like what you're seeing?

Sounds like a problem with the turbo control and/or the check valve for the vacuum chamber.

yes, the exhaust note is definitely louder, more like NA engine tone. However, my concern is, after the secondary came online after 4500 rpm, and I shifted to a higher gear, the exhaust tone is louder, and the turbos will behave like parallel, meaning if it is below 4500 rpm, I will not get boost, but above 4500 rpm, both turbos come on. However, my problem is that it take like 10 second or so nomatter if I am cruising or car idle for the turbo to back to sequential again after a hard pull pass 4500 rpm. Is this happen to guys who have done the seq. simplification mod?

Hook up your boost gauge to the vacuum chamber. See if it's maintaining vacuum - even during boost, it should still have plenty of vacuum. If vacuum is ok, move it to the pressure chamber and see that it maintains plenty of pressure, again during boost and shifts.

Dave

Same Issue
 

I have the same issue. I just had major work done to my motor and baught 99spec turbos (still in standard configuration). Rotary Power in Gardena, CA did all the work. When I get the rpm +4500 (second turbo comes online) and let the rev's come down to first turbo range (3000 ~ 4000), the exhaust note gets deep, loud, NA type. Jeff replaced my primary turbo control soleniod thinking that it might be faulty (they tested it and sometimes it would click sometimes not) but even with the new one I still have that issue. They can't seem to solve it. When I dynoed the car, the boost graph showed no boost before until ~4000 and then it progressed up sharply to 14.8psi. Any help is much appreciated. Thanks.

I am having the same issues as of right now as well. If im doing a hard pull and shifting like I should when the transition occurs you can hear the excess boost being diverted somewhere else. But, if I "blip" the throttle very quickly during the transition the car pulls like gangbusters! I dont understand this at all, I spent 3 hours last night checking all of my couplers and vacuum lines and all is well. Tonight I did the test for the Charge Control Valve which is located on the backside of the y-pipe. This is the test that involves turning the car on and then off to see if the actuator for the CCV moves in/out and it does. Please help w/anything you can.

Thanks, Jamie

Hey everyone, I think my solution will solve this problem. My local Rotary Shop (Rotary Power, Gardena CA) put on a regulator from the turbo's to the pressure chamber. If the turbo control system sees more than 10 psi and the gate starts to stick. What you need to do it add a regulator and set it to 10psi tricking the system into thinking you only are boosting 10lbs. This is for cars that are on seq-turbos boosting more than stock levels. This solved my issue. I'll post pictures later.

My car has been doing this since I did the Seq. Simplification also. Only after a real real hard pull, I have no primary boost, I thought it was a vac hose collapsing maybe

Dave, on the simplified sequential the turbos' do behave the same way as stock, just as you described. I have been running this way for about 2 years and it never fails. If I'm above 4,500 RPM, I'm in parallel mode and everything else is the same as you describe.

Joe

This is the same solution that I went for, and it works for me.
Here is the part you need from McMaster
Name: Brass Adjustable Vacuum/Pressure Relief Valves
Part number: 48935K25
http://www.mcmaster.com/nav/enter.asp?pagenum=432

You may also need this to connect it to vacumm hose
Name: Brass Hose Fitting, Barb X Female Pipe For 3/16" Hose Id, 1/4" Pipe
Part number: 5346K51

Hope that helps.
Reza

To clarify, the simplified sequential simply removes all emissions solenoids. It does not appreciably reduce anything in the turbo control system.

Dave

You got a picture of how you set this up? I'm looking at the part and it looks like it only has an inlet.

It looks like it vents through the hole in the adjust screw.

I forgot to mention in the PM: Tee your boost gauge into one of the lines that goes to the turbo control actuator, and run those boost tests again. If the line holds pressure (or vacuum) when you're not getting primary boost, you've found the problem. If it's the pressure side not releasing and the line has 12+ psi in it, I would look into the pressure regulator solution. Otherwise, replace the solenoid.

Dave

Yeah, that's what I got too. If it's going to be between the turbo and your pressure chamber, if there's only one line in and no line running out to continue to the chamber, how's that gonna work?

Pick up a tee fitting and branch it off of that.

Dave

Turbo Gate Fix - ILLUSTRATION
 

Hey Guys, I have my emissions so I'm not sure what gets eliminated and what doesn't. I have new 99spec turbos, which are boosted to ~15 lbs and I canyon run the car every now and then. I'll post pics though of the simple 10 minute fix (assuming you ahve a pressure regulator and about 1.5 - 2 ft of silicon hosing).

Bad_Karm7, not sure how the simplified seq works (or what is eliminated), the mod attaches between your pressure chamber and turbo (hook it up to the check valve). I'll post pics tonight to help clarify this. They will be night shots though.

Here is what needs to be done though (made a quick diagram):
http://x402.putfile.com/2/5220125378-thumb.jpg

Pictures!!!
 

Here you guys go, took them quickly so detail isn't that great. Also, this regulator is just one that Jeff (Rotary Power) had laying around for testing, once he gets new ones I'm going to go back and get it permenently mounted and get the hosing to match my red.

http://rotaryproject.com/imagesforums/presureReg01.jpg


http://rotaryproject.com/imagesforums/presureReg03.jpg


http://rotaryproject.com/imagesforums/presureReg04.jpg


http://rotaryproject.com/imagesforums/presureReg05.jpg


http://rotaryproject.com/imagesforums/presureReg08.jpg


http://rotaryproject.com/imagesforums/presureReg10.jpg

Thanks for the pics, I knew what would be needed for set-up. The parts he listed didn't make that set-up possible. Just curious how he pulled it off. But as Dave stated to use a t fitting, was what I was thinking needed to be done. I was thinking of just getting the part, calibrate it with my trusty mytivac to 10 psi and call it a day. the whole theory sounds like you guys are on the right track.

Just a quick question. The regulator will set the pressure chamber to 10 psi correct? But when you are running +10 psi boost, dont you need more than just 10 psi of pressure from the chamber, or the 10psi is only need to activate the turbo control solenoid?

The 10 psi reguator is to "trick" the system into thinking you're only boosting 10 lbs (stock levels). The system is setup to handle 10psi max, so when you turn up the boost the system reads these new levels of 10+ psi boost and causes the sticking issue I was talking about in my earlier posts. This mod is just to run 10psi through the turbo control system so it operates as if it was boosting 10lbs. Wont affect the amount of boost entering the motor. I'm boosting ~15lbs on high-boost. and 11 on low boost. This mod solved my issue, now when in the canyons, I don't get that annoying boost lag (reason why I didn't go single turbo).

Can someone who has more technical knowledge of the way the turbo control system works explain this in greater technical details (e.g. sequence of events which trigger the primary/secondary gate to open/close/ Also, it would be helpful if someone explained the stages the primary/secondary turbos are in while describing the sequence; pre-spool, etc)?

Thanks.

Haha! I was the one who developed that system and told Jeff about it when I had my rebuild done a few weeks ago.

In any case, you do not need 10psi. 9psi on the regulator works just fine.

lol awesome, he did mention one of his customers told him about it :-). Thanks! for telling him; man it brought a big a** smile to my face when I tested it out. Howd you figure it out anyways?

Imran, I purchased the pressure bleed screw and tee it into the vacuum lines that goes into the pressure chamber between the check valve and chamber, and adjusted to 10psi. I assume it works the same as the pressure regulator you have showned in the pictures correct?

Yeah, Jeff didn't believe that this unit actually works, until I explained to him the actual function of the device. Heck, who would believe that "some little regulator" could resolve such an issue, right? I was, and still am, planning on doing a semi-extensive write-up on this. I'll give you the gist of it.

After I installed my M2 ECU, I discovered that the increased boost pressure (13PSI at the manifold) was causing the sequential system to respond poorly. I then set it back to 7psi (default wastegate), and everything worked fine. (look up my turbo issues thread that I started if you want the symptoms)

Much like any turbo system with an intercooler, you will see varying amounts of pressure before and after the intercooler on this car's intake plumbing due to the drop pressure of the intercooler. Now, the stock intercooler has a drop pressure of around 2.5psi+ when you see 12psi at the manifold. That means that everything prior to the intercooler, including the solenoid rack, is seeing 14.5psi+! Well, the solenoids aren't even rated for that when new. Heck, some NEW solenoids hardly pass even at stock boost levels.

The immense amount of pressure causes the springs inside to "get stuck". The pressure regulator basically gives the the solenoids the correct amount of pressure needed for them to turn on/off. 9psi is just enough. 14psi+ is a little bit much for these solenoids, especially if they are old. I hope this clears things up for you a little bit.

I don't think a pressure bleed will work correctly; it might work, but you will always bleed pressure above 10psi. You want to just REGULATE it. I'd try to get a regulator. I found some cheap-o ones, but I decided to go with something that I have used on other applications and that I trust. I would go a little lower with the setting, 9psi should be fine. I used a very similar device on the picture above, but mine looked to be a bit better in quality.

I wouldn't mess with a regulator until you have verified that it is in fact a lazy solenoid. How do you find this? Set your boost to the default wastegate setting (7psi). An old/tired solenoid should react just fine under these conditions (as it is probably seeing no more than 9psi). If it still does not react correctly, chances are, this regulator won't really help your boost issue.