LoneStarS30Z

iTrader: (2)

Let me start off by saying I've been doing tons of reading and testing, mainly because my issues originally started as having low secondary boost. I was getting a 12-9-7 boost pattern or something near that. Primary would pull strong and evenly, and would fall flat after the transition point.

So after much checking and testing, I replaced all the solenoids under the UIM, minus the precontrol/wastegate solenoid (the other one I bought had broken nipples). After changing those out, my low secondary boost issue was not fixed, but instead I picked up a new issue, over boosting and hitting fuel cut.

My mods are very simple, just an intake with hard pipes and a cat-back. Still have my stock cat. This is also on a '99, so my restrictor pills are in the nipples, not the hoses.

I ordered the PFC Boost Control Kit in hopes it would control the overboosting and of course things did not go as planned. I've tried a bunch of different PFC settings, sequential boost control on and off, changing boost values and the like with no change at all, still over boosting.

I'm running out of ideas now. I've checked and doubled check all my hoses, and having a '99, I have the simple vacuum set up and all looks good. My pressure tank also holds fine. Following the troubleshooting guide in the FAQ's, it says spiking over 14 can be caused by the hoses for the turbo precontrol and wastegate control actuators. I checked those also when installing the boost controller and they're snug.

Short of putting in my old solenoids, what else can I try? PFC or solenoid/actuator related?

Thanks gentlemen, please bare with me, I just want to be able to drive hard again!

Mrmatt3465

iTrader: (10)

From what I understand, the pfc boost control kit is for a single turbo set up. The pfc can change precontrol and wastegates solenoid duty cycle to alter boost. Because you have a 99 rx7 I believe you have the black box solenoid set up. I am unaware of how exactly that box works but I feel it may just be an enclosure of solenoids? Have you tried testing that box? Did you buy new solenoids or used ones? It wouldn't be unlikely to have bought a bad used one. You said your pressure tank holds pressure, what about your vacuum tank? Do you have a mityvac? It's a great investment to help you troubleshoot these issues. In the FAQs there is also a great link and video to testing actuators and solenoids with one. How do all of your check valves look? Are they the factory ones? I would hit up dale Clark for his awesome check valves. Also, have you replaced the factory vacuum lines with silicone? The heat of the rotary is known to bake the stock rubber lines. A cracked line may not be easy to see.

Matt

LoneStarS30Z

iTrader: (2)

Yup I have the big black box instead of the older rats nest. I haven't tested it because honestly I haven't found any information on testing it. The solenoids I bought were used, I'll be retesting those over the weekend. My check valves looked fine also, but i put some vacuum to a spare one I had and sure enough it leaked. So I will have to look into Dale Clark's check valves. So far I've only changed vacuum hoses on solenoids and check valves I've replaced. Those hoses I changed were actually in good shape, but stiff as a cardboard.

I do have a Mityvac which has been very handy so far. I haven't checked the vacuum tank since it looks like a real pain to get to, plus IIRC that wouldn't lead to the symptoms I'm having.

Thanks for the input, I would like to leave no stone unturned.

Mrmatt3465

iTrader: (10)

The vacuum tank stores vacuum for the turbo control actuator. The actuator is actuated quickly using both pressure and vacuum. If only one form of force is applied, a slow transition will resort ie a drop in boost and then slowly climbing back to 10 psi. Also check your charge control actuator and ensure it opens and closes with key on key off. There's a vacuum line that actuates that valve via secondary turbo pressure. If that line leaks or the actuator is bad, it may stay partially closed. Do you have the pfc set to its basemap duty cycles for the turbos?

Matt

asianguy02

iTrader: (4)

I hate to say it, but you will need to drill out the restriction pills in the nipples to make any changes to boost aside from making it spike at transition or lowering it overall check out here:

Boost Controller

robinette has gone way over my level of professionalism to get everything out there, pay particular attention to the part for tuning the valves for a MBC as that is the info that will help the most

DaleClark

iTrader: (55)

Yep. You will NEVER get good boost control with those pills in there, PERIOD.

If you want to keep using the PFC for boost control, read up on using the MAC valve for doing the boost control. I *think* that boost control kit you have is similar. Or, install an aftermarket boost controller.

Let me know if you need a set of check valves, I have plenty in stock. I don't think it will fix your current issue, but it will help you down the road when the stockers fail.

Dale

arghx

iTrader: (3)

Do you have a Datalogit? If we can see logs of solenoid duty and turbo transition it will help a lot.

LoneStarS30Z

iTrader: (2)

I have checked the charge control actuator, but I believe the thread I was reading on it had somewhat mixed posts on how it should work properly. IIRC, the way mine worked, is when I started the engine the rod pulled in, then when I shut the engine off, and turned the key to off, it released. Then when I turned the key back on, not starting the engine, it slightly pulled in. Then pulled fully out again and didn't move until I started the engine once again. I can double check if need be though, that was a while ago.

I set the duty cycles on the turbo's as low as it can go on the PFC and it looks like it has no effect on turbo operation. I will try to find a way to check out the vacuum tank.

How can I go about drilling them out with getting debris in there? I've seen that link but didn't pay much attention to it, I'll study it more this time, thanks.

I wouldn't be totally surprised if the check valves are bad, I'll look into the ones you provide. I figured better safe than sorry and one less thing to worry about.

I do not, but I should be able to borrow one soon. Lately I haven't been pushing it hard since the overboosting occured, so I don't think I can get accurate logs without me feathering the throttle a bit.

arghx

iTrader: (3)

I'm guessing you lowered "duty" but didn't lower target boost a whole lot. What you did might have resulted in additional instability in the control--overshooting in duty cycle as the feedback goes nuts. I've seen it.

I've never physically examined '99 spec turbos. The pills are built into the pressure source right, not the actual wastegate? If that's correct, you could tap one of your hard pipes for a pressure source instead of messing with the turbos.

You're basically flying blind without being able to take data. You can monitor charge control & turbo control solenoid operation + TPS signal + rpm, which will tell your turbo transition. Then you can monitor precontrol & wastegate duty cycle. Please see https://www.rx7club.com/3rd-generati.../#post10749148

and https://www.rx7club.com/single-turbo...ontrol-900599/ , where I performed target boost & duty cycle sweeps

LoneStarS30Z

iTrader: (2)

Hmmm, just to clarify, what exactly is being set then? Because when changing the settings, it shows a duty cycle, but also a target pressure which I though was what I was adjusting, target boost.

On my turbo's, the pills are built about 1/2 an inch deep into the nipples where the hoses run between the wastegate and precontrol actuators. What would tapping a hard pipe do?

Oh and thanks for pointing out that post in the first link you posted. I've actually used that link before for my idle, but didn't realize that information was farther down in the thread.

arghx

iTrader: (3)

I don't have the magic formula the PFC uses unfortunately. If you have a datalogit you can see differences in boost pressure vs solenoid duty when you make changes. Since the PFC uses some kind of feedback system, when duty cycle is set low and boost is calculated to be significantly below target, the feedback system will have a greater tendency to overshoot.

For a lot of people, you can just play around with the Commander a little bit and get the boost control dialed in. The Datalogit logs aren't even necessary, although they are helpful. When you get into a situation like yours, where you have to troubleshoot, you need to be able to see what's happening on a second-by-second basis.

What sucks is that the PFC requires this $300 box to have that capability. Some other platforms are much cheaper (for most Subarus, it is practically free to have that functionality on the stock ECU). Some are even more expensive.

Again, I've never physically inspected 99 spec turbos that closely. If the pills are only on one side, the side supplying the pressure (not the actuator themselves), well you can just cap them off and get pressure from somewhere else. Drill and tap a hardpipe, install a T pipe thread fitting with hose barbs on 2 ends, then use that to supply pressure for the wastegate and precontrol.

The restricters are simply an orifice. I actually compared them to a bottle of barbecue sauce in this thread: https://www.rx7club.com/3rd-generati...2/#post9414255 . The restricters are totally normal. All sorts of cars using conventional boost control & 2 port solenoids come with them. They can be arranged in different ways and accomplish different goals.

On an Rx-7, the restricter raises boost pressure by limiting how much air can push open the actuators. On a 3000GT, the restricter lowers boost pressure by limiting how much air the stock boost control solenoid can be bleed out of the actuator.

That thread ended up being more like a blog. I update it when certain topics come up. Lately there hasn't been a whole lot left to cover within the scope of the thread's original purpose.

LoneStarS30Z

iTrader: (2)

Hmmm interesting stuff. Kind of an update, it seems that the PFC is actually doing it's job in terms of making sure the engine doesn't overboost. Weirdly enough though the setting on the commander doesn't necessarily represent what value it'll cut boost.

For example, I had it set at .50 kg/cm2 I believe, it cut me off at .75 kg/cm2. I then upped it to .60 kg/cm2 and it cut me off at .84 kg/cm2.

So that's somewhat good news that atleast I'm "safe" from boost spiking, however I still need to find a real way to control it and get a constant target. Because now what it's doing is reaching that cut off point and the PFC is either cutting boost or fuel and the car bucks down hard, essentially still keeping me from being able to go WOT.

I should be able to get that datalogit soon to borrow from a friend, if not I'll be ordering one for myself or hopefully find one here for sale a bit cheaper.

About the pills, do you mean tapping into one of the intercooler hard pipes, or the Y-pipe or something of that nature? I have no problems drilling out the pills, but I'm just wondering how I'd go about getting the metal shavings out. I'll have to check again to see if just one, or both nipples had pills. I looked yesterday and I can't remember which one I checked out, but I was under the assumption both nipples are supposed to have it.

arghx

iTrader: (3)

That's actually in the PFC commander manual, the one that comes from Apex'i. The overboost cut is nominally .25 kg/cm^2 higher than the target. I've seen it hit a little lower though at times.

You could tap the Y pipe or hard pipe. It kind of depends on which one you're comfortable messing with, and whether you are concerned about resale value of the part.

LoneStarS30Z

iTrader: (2)

Ah ok, I bought mine used ofcourse, so I didn't have the factory manual, just the online FAQ from that PaulR33 something or another website.

I may take a look at drilling the pills next weekend, just seems like the best idea in terms on cleanliness. I'll have to make a judgement call next time I peek my head down there.

Next post should hopefully contain some logs for examining as I'm sure I'll be slightly dumbfounded from it all at first.

DaleClark

iTrader: (55)

Drilling the pills out in the car should be a cinch. Pull the Y-pipe off and stuff a rag in there. Get a drill bit that will fit into the nipples and coat it in grease. The grease will trap most of the shavings. After drilling out, blow it out with compressed air and maybe shoot some brake cleaner in there.

It will probably take you longer to remove the Y-pipe than it will to drill the pills out, it's really no big deal.

While you could drill and tap another pressure source, I just don't see a good reason to do so. Actually, on my car, I have removed the stock pressure reference tube coming off the primary turbo compressor housing and drilled and tapped to put a barb fitting in there. It's just cleaner than the stock setup.

Anyhow, drill it out and be done with it. Won't take you any time at all.

Dale

RotaryEvolution

iTrader: (30)

before going too nuts in everything else, test the wastegate with pressure to see if it actually opens. the diaphragm may be torn causing it to not open and has gotten progressively worse to the point of not functioning.

LoneStarS30Z

iTrader: (2)

Bah! Duh! Why didn't I think of that? Thanks Dale. Should I be looking to drill them completely out, or just opening the orifice slightly bigger and testing to see if the boost levels go down?

How do I go about doing that? I'm assuming plug the MityVac into the actuator's nipple, then apply pressure and see if the rod moves?

RotaryEvolution

iTrader: (30)

either apply vacuum like you described or apply about 10 pounds of air pressure from an air compressor to the actuator, the second hose will have to be pinched closed during the test. you can do both since the vacuum test will give you more definitive results but the pressure test will verify the actuator is actually moving.

r0ma

not meanign to hijack but is there any instructions around regarding testing all 4 actuators? I am picking up a mityvac today and am trying to hunt a similar issue as LoneStar with the car overboosting...

LoneStarS30Z

iTrader: (2)

Thanks, will give it a try. One thing that I've really wanting to check is to see if the little c-clip has fell off the rod. I checked the other 2 and they're there, but this is covered up by a big *** heat shield. Been meaning to find a suitable inspection mirror to stick down there, but hopefully this test will tell me more.

LoneStarS30Z

iTrader: (2)

Not sure if you've seen it, but this website talks about the charge control, and turbo control actuators. Although it does somewhat mention the wastegate and pre control actuators, I don't believe it says much about actually testing them. So that kind of info would be great for others having the same issue.

http://www.autosportracetech.com/RX-...leshooting.htm

RotaryEvolution

iTrader: (30)

i doubt the clip is an issue, if it fell off the wastegate would basically be open all the time resulting in low boost versus what you have.

sounds to me like the precontrol solenoid or the wastegate solenoid are stuck open, venting all pressure and allowing boost to overshoot. one simple test you can do is pinch off the line coming out of the wastegate actuator heading to the driver side of the engine which goes to the solenoid. pinching the line will give you the lowest boost that the wastegate can manage based off of line pressure. if it still has the issue then the wastegate is not the problem, but by the sound of it since it does in fact have a transition point still i am leaning towards a wastegate solenoid problem.

the 2 connectors side by side on the twin solenoid pack can be swapped and will also result in a similar scenario. i always mark the wastegate actuator with some paint along with the clip, because it is not easy to discern between the 2 connectors. in the past i have had to cut open the harness a little bit to get a good grasp of the color of the wires to figure out which exactly is which.

LoneStarS30Z

iTrader: (2)

I'm picking up a used precontrol/wastegate solenoid tomorrow, I will be testing it before swapping it, and also testing my current one to see if that was indeed the issue.

There's an AzeKinghtz solenoid rack for sale right now and I'm contemplating buying it, I think it will be well worth the extra money ($580 more than I'm paying for this other solenoid), but I think it'll for sure rule out any solenoid issues in the near future. Whereas just replacing a bad solenoid with another used one may yield the same issue after a while.

DaleClark

iTrader: (55)

The stock solenoids aren't as big of a problem as people make them out to be. I have original solenoids on my car (122k) and a perfect boost pattern.

Really, I don't think the aftermarket solenoids are worth the money. Use the money for something your car really needs.

Not to mention from your original post the solenoids seem OK, it's your boost control that's gone wild, and that's simply what happens when you open up exhaust and intake with the factory pills and boost control. Get good boost control and you're done.

Dale

adam c

iTrader: (2)

Since your transition boost is 9 psi, I would drill the prespool nipple as little as possible. A tiny bit of drilling goes a long way.

The wastegate nipple can be a little more than the prespool nipple. Again, a little drilling goes a long way.