I have an all stock car, with the exception of a DP. Car is 90k miles, had a hose job done 5 years ago. No CELs. I plan on keeping her sequential.

The problem: Sometimes with 2nd turbo does not come on. I have not found any circumstances that cause it (like only when its hot, only this or that, etc). The only thing i have noticed is this:

if I start in first gear, go WOT and roll through the gears, the 2nd turbo works every time. But occasionally (over half the time) from a 2nd or 3rd gear roll, I will only get the primary turbo all the way to redline.

I also have noticed almost EVERY time ... say i am at WOT at any RPM where the 2nd turbo should be on. If it isnt on, i can chop the throttle off, then WOT again and it will kick on like it should.

I have been doing searches and reading about this for a week before I am posting this. If anybody has a good idea on a really common culprit for this problem, I appreciate it.

One 7 owner suggested I pop the lines off the solenoids and spray WD40 inside of them, but I am leary of this.

I have sprayed around vacuum lines and UIM/LIM with some brake cleaner and found no obvious signs of a vacuum leak. And I removed the UIM not long ago to replace a dead coil and didn't see any vacuum lines popped off.

Thanks guys.

Todd.

 

Probably the check valve going to the pressure chamber. If you can suck air both ways through the check valve you need a new one.

 

This sounds like it could also be a solenoid issue. Def check them for sticking and/or failure! I had the same sort of thing happen fairly regularly on mine until I swapped to an aftermarket solenoid setup.

There is an excellent write-up on how to check and test your solenoid floating around on here. Unfortunately I can't find it right now though =( Maybe somebody else can chime in with it?? (Paging Mr. Links: Mr. Links, please render assistance on aisle 3..)


And... A shameless plug for somebody I've NEVER met... AzEKnightz is making replacement solenoids now, they are based off the original aftermarket solution offered by Rob Bailey (aka Saxyman, aka "Axiom") which I used to have. The Axiom Solenoids worked WONDERS and I can only assume that the ones made by Eric (AzEKnightz) will be just as good.

Here is a link to the group buy Eric has going on currently. It's just an option to keep in mind... https://www.rx7club.com/group-buy-product-dev-fd-rx-7-269/custom-solenoid-rack-968956/

 

Usually it's a solenoid after the engine is hot and the check valve after you've run through the gears chill and then roll into it again of course it could be 10 other things as well. Sequentials; love em, hate em

 

Yep. Agreed. I would just add: Pay particular attention to solenoid 'E', the pressure side turbo control solenoid, as it seems to be the one most likely to stick (under pressure) causing unreliable operation and some of the symptoms you've mentioned.

Note that solenoid E may test fine in a static test--so perhaps the best approach is to swap it out and see if there's a difference. If bench testing, apply pressure to the TCA port and see if it will release after cycling the solenoid.

 

ok, i removed all boost pipes, find a little split on the one going to the y-pipe. it was not between the hose clamps, so i doubt any air was seeping through it (but i will replace it anyways).

News update: The reason I checked the boost hoses is because I temporarily installed a boost gauge that I have had laying around. Car holds about 17in vacuum at idle. This things boost is very confusing. I have not had the car long, and i assumed i was making full boost but...

It seems to only boost 6 to almost 8psi boost tops. When the 2nd turbo kicks in, boost drops from 7 to 6 then holds about 5psi. Sometimes i can romp the gas and the boost will spike to 8psi for a few secconds, but once past around 5500 or 6k, it starts dropping back to 5 psi.

A few times i tried punching it in 2nd gear and it would boost over 2 psi on primary. then i'd shift to 3rd and it would jump back to 6 to 7 psi again.

I just dont get why its so random.

Initial visual inspection of the turbos after i removed the piping looked good, linkages attatched, vaccum lines look decent.

 

Also forgot to mention ... when i was doing the 2nd gear pulls and not registering any boost ... I could hear a very muffled blowoff valve type noise when i let off the throttle. Again, my car is 100% stock except for the DP.... but it sure sounded like a super low pich whistle version of a bov.

Fun stuff (sarcasm)

I saw the solenoid rack in the GP section. I like the stock sequential, but looking at all the mods... solenoid upgrades, efiiny y pipe, turbo rebuilds, etc ... sure seems about the same cost as a brand new single turbo. I'd like to diagnose this though, going to go test the check valve real quick.

 

there is a possibility the check valve between the y pipe and the turbo was pointing the wrong direction. I pulled it to blow through both ends (can only blow through one side) then i could have sworn it was pointing the opposite direction of what the vacuum diagram showed. Im tired, so i could be wrong, but if so it was making it a vacuum chamber instead of a pressure chamber.

I will put it back together tomorrow night and see if its any better. And look into that solenoid E testing stuff.

Any more tips, let me know. Thanks guys.

 

Sir, i have the exact same problem with my diva

You are not alone´... I will do a full hose job (has been never done on my car) and hope the best!

good luck!

 

If you are only getting 6 psi on primary it won't go to secondary, now you have to figure out why you aren't getting full boost. I had the same problem it was a hose not connected in my case.

 

My check valve fell off. I put a new one on and it works.

 

You need to replace the split crossover pipe which should bring the boost up on both primary and secondary.

The blow off sound is a bad TCA which is why you are only getting the secondary to come on when you shift from 1st to 2nd or run through all the gears and don't lift off the throttle keeping TCA pressurized. If for example you leave it in one gear and accelerate breath of the throttle and try to accelerate again it may or may not work depending upon how much pressure the TCA lost.

I have those parts in good shape and will PM you

PS I may be wrong but I'm pretty sure all the check valves should point to the engine.

 

Here is dgeesaman's thread on Testing Solenoids.

Here is arghx's thread on the Twin Turbos ( I also recommend all of his why is this engine so damn complicated threads )

Websites for troubleshooting these turbos:
Here and Here (<-- if you look at nothing else look here)

and the thread where I found all of this FAQ for 3rd Gen & other useful links ( It really is useful )

 

^^ thanks for the info, i will tinker with it some more when i get off work. Is all this stuff the main reason people switch to non-seq or to single? I keep hearing that sequential is problem after problem to keep it running correctly. Still new to the FD, I have only owned this car a few weeks.

 

Not necessarily so. I have had only 2 or 3 problems with the sequential over the last 18 years, which is not a bad track record. Take some time to learn the system and sort it out.

 

No luck so far, but my time has been very limitted. Replaced the Y-pipe hose last night and checked all hoses between the turbos and the engine. Vaccum and Pressure tanks both seem to be doing their job and related check valves are functioning.

 

Check under the pressure tank and make sure hoses didn't come unplugged, if they do you will only get 5-6psi, also make sure they aren't brittle or cracked as it could cause a leak and only get full boost intermittently. I had 2 not connected when I bought it and had the exact same problem as you, hooked them up and it fixed it.

 

I have the same problem. When i rew it up at idle i can hear that the reliefvalve makes noise at first time but when i rew it up again right after the rews have lowered the relief valve is silent ant the boost wont rise. As in motion (autotranny) when i floorit it will or will not start the second turbo but after ill pump the throtle it will some case start the second turbo. Now its winter and i have stripped the engine bay, I found out that one of the check valves was broken (split in two in the middle) and the other one had huge crack on it. I will replace them and will report at spring if it did the trick.

 

Rats nest is out of the car. I have one broken nipple on the solenoid “C” (vacuum swithing) and I broke one of the 2 solenoids that sits right under the UIM. It had epoxy on it and just the slightest pressure broke it. As far as solenoid “C” I really don’t know if I broke it during disassembly or if it was already broken.

I may order some coolant hoses while I am in here, but I may not have an update for a while. Whenever I figure out the issue, I will post it. Tedious work to say the least.

 

You have some solenoid work infront of you.
If you plan on staying twin seq, i can really recommend the solenoid kit Aezknight is throwing together now. A new solenoid will set you back what? 100 bucks or so at mazda, and a used one, well its at least 10 years old and could go a few years working, or die on you in 3 weeks, and your brain will tell you "i replaced this one 3 weeks ago, cant be this one" and throw you out on a wild goose chase.
The Aezkit is mid 600s dollar, gived you the 4 solenoids you need, serial connected so you remove a bunch of vakuum hoses, you can remove a bunch of solenoids(if you are in a non-smogcheck state), a perfect wiring loom, quick disconnect on the wiring loom, bracket for alternate placing to get it out of the oven over the shortblock, you get new checkvalves with viton seals.. Its just a mechanical piece of **** engineering...! People are reporting back on this kit as being just... awesome! Insane response, superbly put together, quality parts..
I cant wait to fit mine when the engine arrives from the states.

 

I may resort to that... we will see.

 

Remove the sequential system :-)

 

Or.... Don't listen to the newb.

Get the seq system working right and you will love it!! If not that then just go single, don't waste you're time with non-seq crap, it's the worst of both worlds and not that much cheaper.

 

Ok, I have done a complete vacuum hose replacement on the car and replaced all check valves with new ones. Still getting around 7 psi primary and 5 to 6 on seccondary. If I disable the electronics and just use wastegate pressure it runs a 6-4-6 boost pattern. With the electronics in place it runs more like a 7-9-5 pattern. And the transission seems late, but I can't confirm it (tach is not working)

 

I absolutely recommend Azeknightz kit. I just installed it on my car and it is awesome! If you're doing the vac hose job at the same time you can eliminate the factory solenoids and simplify your ratsnest! I'll post pictures of my simplified rats nest