mikejokich

iTrader: (1)

Here is my current mini pressure regulator. Norgren R07-100-RNEA
Mike

ndinunz

Update:

So, I decided to put the car back together with one of the new solenoids that had the least amount of symptoms and the rest of the solenoids switched around in different positions, such that the ones controlling the twins were the best of the bunch.

Good news is that I put it back together right, because the car runs, drives and goes into boost just fine. It also seems like throttle response after shifts is maybe a tad improved.

Bad news is, I checked with a boost gauge to the manifold, and it looks like I'm getting a 5-3-5 boost pattern. The car basically feels exactly the same as it did before I pulled the rack. The pattern is definitely right, drops briefly during transition and then holds 5psi all the way to fuel cut. I can definitely feel the car squat down when it gets into boost, but it just feels like it's not making ALL the steam. It doesn't feel particularly slow, but it also doesn't feel particularly fast. I'm not sure what a stock car should feel like. I've been bench marking against a friend of mine with an 8th gen accord v6 6 speed, and he pulls on me pretty good from any speed roll. I feel like the FD should at least be able to keep up with that car.

Does anyone have any advice as to what could be causing this symptom? I feel like the solenoids are working correctly at this point, it's just not making as much boost as it should.

I've read in some other threads that potential causes may be a clogged cat or boost leak. I do have a catless downpipe, but a stock midpipe. Could be worth a try to switch those. I've bench tested the CRV and the BOV and they both tested fine, but it may be worth testing again. I do notice a hissing when I get into boost. I'll step away from the solenoids and check there.

boostin13b

Glad to hear the boost pattern is right after all of that.

Clogged cat - definite possibility

Boost leak. Are you stock intercooler and piping? A lot of the rubber and plastic piping/couplers are known to split with age. May be hard to see at first glance and you may have to feel them out if you can't boost leak test (which is harder to do with the twin setup.)

What kind of Intake or air filter are you running? Clogged air filter can cause this. I have also seen when people run cone filters, they may slide it on too far and the end of the cone filter actually blocks the intake pipe acting like a clogged air filter.

ndinunz

All good points. I'm currently on the stock airbox and stock intercooler, almost all of the couplers are still factory. I'll go through them all and check for leaks.

I also happen to have a catless mid pipe in my garage, so I can pop the factory one off and throw that one on if I can't find a boost leak.

I'll update once I can get back into it. If it's something as simple as a boost leak and I don't have to tear the rack out again, I'll be ecstatic.

gdub29e

iTrader: (16)

It’s been a bit, so I will have to reread the thread before I can comment. What ecu are you on?

Also, do you have a workshop manual?




~ GW

boostin13b

If you are on stock ECU watch out with that catless midpipe. I would go easy on the throttle just to see if you can boost above the 5 psi and that will let you know if it is the cat but don't go full throttle and rev it out, You will overboost and risk popping your engine without a cat and stock ECU.

Definitely pull out the filter and make sure nothing is blocking the intake for the box and the filter isn't plugged.

ndinunz

Thanks for the precaution. That’s why I haven’t installed the mid pipe yet, because I’m on the stock ECU. It would only be on there just to test. I will be sure to be careful with my throttle input. I will also be sure to check the factory filter and inside the airbox.

I do not own a workshop manual, but I assume they can be found online.

gdub29e

iTrader: (16)

Here is the online version. http://foxed.ca/rx7manual/manuals/93...highlights.pdf

Since the car is almost completely stock. How many miles are on the turbos?

ndinunz

The chassis has about 81k miles on it. I think it would be safe to assume that's how many miles are on the turbos. The car received a reman engine around 15k miles ago.

ndinunz

Also want to quickly mention that the boost pattern is the same regardless of what gear I'm in

gdub29e

iTrader: (16)

Got it.

Since you have a pretty nice boost pattern, but it’s just low. I think you can forgo testing the turbo control. You need to test the Westgate and pre-control actuators. Go into the manual and look up section F-84. The specifics for testing the actuators is on the following page. If you do not have compressed air with a regulator an easy tool is to get a minivac that does vacuum and pressure. Test them to make sure that they’re working correctly. I would double check that your wastegate and pre-control solenoids are operating correctly. They are located on the uim right behind the pressure chamber. Pretty easy to get to those.

For the sequential system to work correctly both the Wastegate and pre-control have to work together. Initially, the wastegate remains closed during primary operation and the pre-control bleeds as needed. When the secondary Turbo comes online the pre-control is closed and the wastegate takes priority.

I am hoping that it’s just something as simple as a clogged cat, But I have a feeling it may not be. The early sequentials specifically the A1 are know For extreme cracking. If the wastegate area around the flapper is not sealing correctly, you will run into low boost. The fact that you’re seeing low all across the board is kinda an indicator of that. I would check the cat for being clogged and any intake obstruction as suggested. I personally would not put a straight pipe on a stock car. It’s just asking for trouble. I Would, however suggest to smoke test the intake. Pretty easy to do with a cigar and a minivac.

One last thing. How are you reading boost pressure? Do you have an aftermarket gauge installed?
Do you know if they installed the boost restrictor pills?


~ GW

ndinunz

Awesome, thanks so much for the advice. I will definitely go through the procedure in the service manual after inspecting the intake system for leaks. Noted on the straight pipe.

I have tested those two solenoids, but I will test them again as well as the CRV and BOV since I'll be in there anyway.

I'm testing boost pressure with a gauge hooked up to one of the ports on the UIM. I do not know the status of the restrictor pills.

ndinunz

Also, in the service manual you linked, the F section only goes to 78. I found the full manual online, though

gdub29e

iTrader: (16)

I’ve never used the online one since I have the actual hardcopy so that may be very accurate .

Wastegate and pre-control restrictor pills belong in the lines between the actuators and the primary turbo. These allow the factory solenoids to operate correctly. Arghx had a nice thread on this. https://www.rx7club.com/3rd-generati...tified-841821/


After chatting with one of my OG friends who is also a forum members, we both think a quick testing procedure would be to disconnect the wastegate and pre-control lines. Loop them together and then go run the car. Don’t go out and floor it, but see if that Increases the boost. The cracking spring pressure for the factory actuators is 7 psi. You’re not even obtaining that at this point. That would be a quick way to diagnose. Again, just don’t get too excited

~ GW

ndinunz

Just flipping through the manual, I read that as well. What's interesting is that can definitely feel the boost pressure drop at the transition point, and this was confirmed by the boost gauge. So I think the flapper is definitely operating correctly, which is interesting.

So, if pulling the lines from the gate and precontrol DO increase boost pressure, what does that say exactly? That the actuators are faulty?

gdub29e

iTrader: (16)

I would pull the lines at the solenoids up top. It’s a lot less to take apart. If you were to unplug them at the solenoids up top and leave them open… You would effectively be on spring pressure. The factory cracking spring pressure is around 7 psi. So you should see 7/5/7 On the boot gauge or something like that. When you loop them together, you effectively add pressure since it cannot bleed away to the backside increasing the cracking psi pressure. What we’re hoping to see at this point is the boost increase. Just remember to take it easy you just wanna verify. You don’t want it to spike by flooring it. Again, this is just an evaluation.

if you see the boost pressure increase drastically then it may be one of the actuators and or missing the pills. If it stays the same, then chances are the wastegate is either sticking or the sealing area is destroyed.

~ GW

ndinunz

Thanks again so much for the advice.

I just want to confirm this testing procedure 100%. You're suggesting I pull the lines off of the wastegate and the precontrol solenoids (solenoids I and J respectively on the vacuum diagram). Each solenoid has 2 ports. Are you saying to loop the top and bottom ports of each solenoid together or are you suggesting to loop the I solenoid to the J solenoid? Just want to be sure my testing procedure is correct.

Thanks

gdub29e

iTrader: (16)

Each of the solenoids have two ports. One of the ports connect to the pre-control / wasegate via the hard piping and the other is actually just a return line back to the primary Turbo elbow. In OEM configuration, it has to remain a closed system for emissions.

You want to loop the pre-control actuator and wastegate actuator hoses together. They will be the individual ones on the hard piping. The return side actually is tied together right at the top with the OMP Lines. It has a large section that has them tied together. I cannot remember whether it is the top port or the bottom port because I’m not standing in front of my car at this point and able to trace the hoses back those few inches. I think an easy way to do this would be to pull them off at the hard piping and make a loop right there.


~ GW

ndinunz

Got it, I’ll try exactly that and report back. For anyone else who may be facing similar issues, they would be the top ports on the solenoids.

ndinunz

I just tried that exact test. Took the pre control and the wastegate lines off of the hard lines, and connected the two hard lines with some silicone tubing. Absolutely no change in performance. Boost gauge still confirms 5-3-5

ndinunz

Upon some inspection, I found this huge hole in the coupler connecting the upper charge pipe to the pipe coming off of the bottom of the intercooler. Going to replace the coupler as soon as I can and test again.

gdub29e

iTrader: (16)

Yep, that will do it. Reconnect the wasegate / pre control hoses and replace that coupler. I would still take the time and smoke test the intake. Here is an easy way to do that.


~ GW

ndinunz

So I got a hold of a new coupler, reconnected the waste gate and pre control solenoids and retested. The results were encouraging, but my problem is not completely solved.

After fixing this boost leak (maybe still more to be dealt with) I’m now getting a 10-3-5 boost pattern. The primary turbo comes on strong and holds 10 pounds. I can definitely feel the flapper opening at the transition, and the boost gauge drops to almost nothing, then spools back up to 5psi. Towards redline, the needle on the gauge jumps around a lot, between 5 and 7 pounds it seems.

I’m wondering if maybe the secondary turbo isn’t prespooling, or perhaps, the wastegate actuator is faulty. This is a guess based on the fact that the needle on the boost gauge drops so far at the transition. I also wouldn’t be surprised if there is another boost leak somewhere, although it does hold 10 pounds up until the transition so I’m not sure it would be a major contributor to my issue at this point.

Does this information potentially help indicate what could be causing my problem to those of you who are more knowledgeable about the twin control system?

I’m going to be out of town the whole weekend, so I can’t do any more testing, but I will certainly be brainstorming and researching. Once I get back, I’m going to smoke test the intake system, do a deeper inspection for more leaks, and retest with the pre control and waste gate hard lines looped together again to see what I can learn.

gdub29e

iTrader: (16)

Before you start chasing your tail you need to do some basic testing. Start with smoke testing the intake and eliminating any leaks. Then, you need to test the wasegate / pre spool actuators. Then test the turbo control actuator. Then the charge control and charge relief. I get that’s not fun but you need to know that they are working correctly before you proceeded. There could be a number of things causing that secondary turbo being low. After you verified they are working correctly we can continue.



~ Gw

scotty305

iTrader: (2)

When the wastegate is open, it will vent exhaust and prevent the primary turbo from spooling. If you force your wastegate solenoid to 100% duty cycle, you will never see more than 7psi on the primary turbo.

If you have low boost after the secondary transition, I would look for problems with components or vacuum lines related to the charge control valve or charge relief valve. Or check for leaks between the secondary turbocharger outlet and the charge control valve, because those leaks wouldn't affect primary boost at low RPM when the charge control valve is shut.