YoshiFD3S

iTrader: (19)

My FD is running stock twins, sequential. Twin-intakes, down-pipe, stock cat, and cat-back exhaust, some oldschool APEXi AVC-D, and S-AFC II.

Plz listen carefully.

The problem is that in 3rd, 4th, and I believe 5th, if I boost...it'll hit 10psi, then slowly creep up to 12psi and even a little higher until it hits fuel-cut. I AM running stock ECU, and NO I don't want it to be pushing that much boost. I just want stock boost. But even if I disconnect the AVC-D it doesn't make a difference. So I'm TOTALLY like "WTF" right now. The problem is that I don't know what the hell is causing it to boost like that. A few times, maybe 2 days ago, it would boost pretty solid in like, 1st gear, then when I shifted into 2nd, it would literally only boost 2psi, and I'd swear you would only hear one of the turbos spooling. Today it kinda did the same thing, except 5psi.

If I'm already in 1st or 2nd gear and I go full-throttle, but shift slowly enough, it seems to be boosting more stable, at about 8psi to 10psi, solid. Jesus, I'm hardly even sure how much I am supposed to be getting in each gear. These were NOT problems I expected to experience with the car so early in having owned it. The seller did NOT mention any of these problems whatsoever to me. *sigh* Don't ask.

Another problem is that while boosting under full-throttle, I will get one stutter that causes me to lose alot of boost. It seems to happen about 1 to 2 times as the RPM's increase. I'm honestly guessing it's the spark plugs. She is due for a tune-up, according to the seller. I have NGK 9's, Mazda OEM filter, and some Taylor Pro spark plug wires w/ braided cores, ready for tomorrow.

Now then, There are a few things I want to point out though, that might help you guys better analyze the situation. Currently, there is an APEXi aftermarket BOV installed...VERY ghetto-like. It seems to be hooked into one of the air lines that would normally hook up to the air pump, or whatever that 2" or so, sized line that sticks out on top of the rear turbo is.

AND the stock "BOV" is still there too. WTF. It's right where it should be, location wise, but it is also blowing atmospheric.

Previous owner installed an oldschool APEXi AVC-D, and tonight I basically found out that there's no way it can be hooked up right. Even if I disconnected it, it wouldn't make a difference, so that leads me to believe it's something vacuum line-related. I don't know.

I DO plan on removing that stock BOV and replacing it with either the APEXi, or purchasing a Greddy Type-S off a friend, and put that in it's place, as should be done. Right now the air-pump itself is not getting power, the plug is disconnected, since it as well, it no longer hooked into the stock air box, or even the intake. Read below.

I'm guessing that maybe one of the reasons why these problems exist is because the previous owner did not install PROPER intakes for the turbos. From what I've seen, like on the APEXi twin-intakes I believe, the air pump and other stock devices are supposed to be connected to that intake piping. That is not the case with this intake setup of mine.

- Besides the BOV and disconnected vacuum lines, I'm not sure what else it could be. I don't even want the stupid APEXi AVC-D in my car. It doesn't work, and I obviously don't WANT to be running more than stock boost on the stock ECU.

One of the things I'd like to know (and do NOT tell me to search for it), just what IS the regular boost pattern I should be getting in each gear? How does "10-8-10" work? Is it like that in every gear? First it boosts up to 10psi, then as the butteryfly valve opens fully to the secondary turbo, it lessens to 8, then increases back to 10psi? Seems simple enough. Is that correct?

Ugh. It's very disheartening to have these kinds of problems with the car already. I'm so scared that when I'm trying to test it out on the highway, and it hits that fuel cut as the needle goes a hair past 12psi on my gauge, that I'm gonna blow my motor. But at the same time, I was trying to test adjusting the boost controller lower, thinking it was actually hooked up properly.

God. Help me figure this out.

I'm taking it into Mazcare tomorrow for a scheduled compression test and overal diagnostic, though I'm hoping to get some input from you guys too. Mazcare is the type of rotary specialist shop that thinks all rotary cars should be left stock...or so their attitude leads you to believe.

:[

P.S. For stop-and-go traffic, and just regular cruising, the car drives fine. No stuttering, no nothing. It's under this full-throttle boosting, that I'm having these problems.

P.P.S I gear a hissing sound from underneath the shifter, or around it. Leads me to believe there is an exhaust leak by the o2 sensor on the down-pipe, possibly. Might explain why he told me something about the check engine light being on because the o2 sensor isn't hooked up?

dgeesaman

iTrader: (7)

I suggest you check that cat to be sure it's not gutted. It should weigh a ton and the matrix should be visible from the front pipe using a flashlight.

Check to make sure all the lines between the primary elbow and boost controller (beige, light blue, pink, and green lines on the diagram) are intact and not crossed up.
http://www.davidgeesaman.com/rx7/93v...lor.edited.jpg

The inconsistent behavior is probably caused by bad check valves or a sticking solenoid or two.

IME, the way to fix it is to do a full rats nest job, and use a Mityvac and 12v power source to test every solenoid both hot and cold. (Or, buy all new solenoids for around $300). I just buy a block of old solenoids, test them all, and use the ones that work best. And then verify EVERYTHING with the vacuum diagram.

As for the AVC-D, I'd swap it out too, and install a manual boost controller, Damian and DaveW style.

10psi should be acheivable in all gears. Sometimes one gear runs a psi higher/lower than the others, but essentially they should do the same.

Of course the seller won't mention those things. People selling FDs know the buyer is at a major disadvantage in trying to determine the problems. That's why buying an FD is so difficult if you haven't owned or worked on one before.

That's a good first step. However, it's probably unrelated to the boost issues.

Are you referring to the secondary turbo inlet, or something on the Y-pipe? Sounds like it's installed in place of the regular BOV. I suggest you figure out exactly what it's connected to.

Stock setup has two BOVs - one for regular BOV duty, and one for venting prespool air. Both vent to the stock airbox to reduce noise. Like Dale says below, there is not much 'wrong' with the stock valves, and the aftermarket BOV provides no real benefit.

Do you need the air pump or not? If not, do a full removal. If so, get the missing parts and hook it up properly.

Yep, and all gears should look pretty much like that. There are a couple of items at the bottom of my page that should help explain it further: http://www.davidgeesaman.com/

I think going back to stock (at least as far as replacing the stock turbo control system and using a basic ball-spring manual boost controller) is the only way to ensure things are working before you can move forward. So if Mazcare has indicated disappointment with haphazard mods, and they aren't interested in sorting out a mess caused by poor choice of aftermarket components, I don't blame them. It could easily end up with a monstrous labor bill, unresolved issues, and you're unhappy. Not that it's your fault - but you've inherited it and it's not expensive to replace all the parts with used stock parts and get all that working ok first. For about $200, you can buy a good Mityvac and all the solenoids, stock airbox, and turbo valves you'll need to test and build a running turbo control system.

Or the secondary air injection tube. But check the O2 sensor as well.

Dave

dubulup

bravo dgeesaman

DaleClark

iTrader: (55)

That's one problem with buying a pre-modified car - it's hard to tell whether the previous owner knew what the hell he was doing.

One thing to know - stock, there is basically 2 blow-off valves. One is the true BOV, the other vents the second turbo's air while it's in prespool. That is correct how he has it set up - you typically just replace the BOV. Really, the stock BOV's are VERY good - flow well, respond quickly, and even make a keen "pssh" noise if you open-air vent them.

Do you have any underhood pics? We could probably offer some more advice on how he has the intake set up.

I HIGHLY recommend getting the colored vacuum line that Dave linked to above and making a good printout of it. With it, you can solve a LOT of the problems and see if hoses are set up properly.

I would also try and keep that Apexi boost controller to some extent. It's not a bad one per se, and with your mods you will need a boost controller or you'll get spiking on the second turbo's transition.

As a start, new plugs and maybe a new set of check valves - that goes a LONG way. Then, start the deep troubleshooting.

Dale

areXseven

iTrader: (1)

Applaud, Applaud, ...APPLAUD!. That is one of the best responses I've ever had the priveldge of reading on this Forum! Great effort on the part of Dave a/k/a : dgeesaman!!