Garrett

I had a peculiar boost problem wherein my secondary boost would not come online when my car was warmed up (intake temps at 40 C and above). This was very weird and nobody really could give me any answers. So I set out to solve the mystery.

I did the silicon vac job. Holy ****, is that a ******* mind numbing humbling thing to get involved in. Well after thoroughly checking everything and replacing every single one of my lines I found nothing unplugged or wrong visibly. I scoured the Internet in a desperate search for answers, then came upon a thread that suggested the same circumstances I was experiencing. It involved the turbo control solenoid. What happens is, this thing heats up and gets damaged because it is directly on the Air Control Valve. So, because that is linked up to the intake, when the air got to be hotter than 40 C, my solenoid quit working.

On a hunch, backed up with this information, I bought a new one. Presto! I have full boost with no hesitation. I am also betting that a lot of secondary turbo problems arise from the malfunction of this solenoid due to its location. So, if any of ya'll have this particular problem, then here is your fix.

The car transitions perfect now and better than ever before. I was always wondering about this and it has been a nuisance all along.

Thanks for listening and good-bye!

psi4psi

where exactly is this solenoid located?

BTW thanks for posting the solution, no many do that

Garrett

Look on the vacuum hose diagram. It is called Solenoid Valve (turbo control) and is right on top of the Air Control Valve (ACV).

http://www.scuderiaciriani.com/rx7/v...placement.html

LAracer

Great thread! It's good to hear about solutions as well as just problems.

Cihuuy

great detective work!! you have just solve one of the many problem of the 7...

if the turbo control solenoid had stoped working... imagine all the other solenoid on the rat nest, directly on top of the engine??

Did you move the location of the turbo control solenoid then??

adam c

iTrader: (2)

That's great. Thanks for sharing.

Garrett

No, I did not move its location. I will look into that. It does sound like an excellent idea.

rx7dave77

Thanks Adam for letting telling me about this one. Garrett, what did the part cost you? I don't have temperature problems, but mine is still picky about when it wants to give me full boost.

M. F. Luder

thanks for the info Garret. I would also like to know how much it cost you & where you got it from. I called a Mazda dealer here in MA, but the parts guy i talked to didn't know what I was talking about. You wouldn't happen to have a part number or something like that would you?

Garrett

Cihuuy: I was thinking about the rat's nest potential for heat damage and yes the heat off of the engine would certainly be a problem. However, the only solenoid that is shrouded in a heat shield is the turbo control solenoid. I am thinking that this solenoid takes the most abuse from heat. I also can imagine that the placement of the rat's nest is peculiar, so maybe it could use a shield of some sort. I am not sure why it isn't more protected from engine heat.

The part number for the turbo control solenoid is N3A1-18-741.

Don't buy this from a dealer, they will overcharge you. Buy it from Mazda Performance out of Huston. They are very professional and the best I have dealt with so far. They will also be able to help you if you don't have the part number. Almost all of their business comes from RX-7s, or at least that is what they told me.

http://www.mazdaformance.com/index

I am not really sure whether replacing the turbo control solenoid will fix your problem rx7dave77 but it wouldn't hurt to try it. I did it without testing to see whether it is the culprit or not. I was just ******* tired of paying 200 hundred dollars every time I tried to get it fixed and did it without properly diagnosing it. Granted it was a pretty weird boost issue with seemingly no hope I just couldn't take it anymore. Though it is fairly vain to just replace it, it maybe worth it in the future when it starts fouling up.

The placement of this solenoid is easy to get to. It isn't like accessing the solenoid rack. All you have to do is remove the Upper Intake Manifold and there it is.

In case you would like to properly diagnose a potential boost issue, you can use this link to help you out. It goes into a lot of technical jargon that I have just recently become acquainted with but it does serve as a thorough resource for any boost issue.

http://www.scuderiaciriani.com/rx7/boost_problems.html

Garrett

donsmith

What was your weird boost pattern before the fix. No boost, low boost, spikes?????

Garrett

My problem was as I stated in the first sentence. I don't mean to sound redundant but when my intake temps got above 40 C the secondary turbo would not come on-line. Also, in which I didn't mention, I would get an occasional boost flutter at transition and sometimes low boost after the secondary kicked in. I really never had a boost spike. I think I suffered from just about all the related problems with a turbo control solenoid going bad.

Hope that helps. I'm feeling extra pressure from your 5 question marks.

Garrett

FDsmilin'

Hey everyone, just found the forum yesterday. I just gotta thank garrett, this problem has been plaging me for the past 3 months...hopefully this will take care of it. I will let everyone know. Thanks again.

Cihuuy

Garrett: im not sure if there is any difference in temperature, whether it is near the acv or the rat nest! But just as long as the solenoid does not touch any part of the engine, i think it would be fine...

What i did when i did the simplification setup is that i fabricated a new metal to hold all of the solenoid that is left. I position it bellow UIM, so that i can easily check for loose/poped hose. Not sure if it will help from the heat tho...

rx713bt

iTrader: (4)

The exact same thing happened on my friends car. After warming up the turbo control solenoid would quit working and the 2nd turbo would not kick in. It was quite difficult to toubleshoot. I heard you can stick the solenoid in the oven and bake it to 200 degrees F and apply voltage to it to check it it still works.


-Jeff

Cihuuy

Its weird how the solenoid stoped working at certain temperature?!? is this a defect or does all of our solenoid are like this??

Toadman

GJ! We need a sub-forum under 3rd gen titled "boost troubleshooting". With 72 vacuum hoses and numerous valves/solenoids, it's almost mandatory.

Garrett

Toadman: Yes, that would be a good sub forum. I think it would be nice to have an arena where, as in my case, you can share a fix or share a problem. Well, I guess you can still do that in the 3rd gen forum. But, it would be handy to just have it plain and easy to find nestled in its own sub-forum.

Or maybe, make a sticky where people that have had a boost problem and fixed it can post their problem and its fix. Don't know if that would work, given the plethora of questions that come with a boost issue from the victim of a boost malfunction. The sticky might be overloaded with discussion of a particular aspect instead of posts consisting of boost fixes. Come to think of it, it wouldn't hurt. I mean, most stickies get overrun with post after post of futile comments. We might as well try a sticky that holds hope for sufferers of boost issues. I almost threw in the towel over this boost problem, so I can imagine that others are equally as disheartened.

Garrett

jayk

You didn't, by any chance, have a loud whistle that accompanied the second turbo not working?

Also, how much did the part cost from the place in houston?

ExpensiveHobby22

Hey jayk, that whistle sound would happen to me when the "blow off" (i know that's not the correct term) valve for the 2nd turbo came out of the hose it's normally connected to. The air would rush out of the hose it used to be connected to, hit the valve, and make a whistle.

My friend also had the same problem except it tunred out to be the hose burst and would whistle.

rx7speed811

i wish i had read about your successful solution to this problem way back when i had my fd and the stock sequential setup. it very well might have fixed all my problems, it sounds like. this was well over a year ago, but i remember being so frustrated and disappointed after doing the long tedious hose job, checking everything over twice, and still getting no boost after putting everything back together. good work, garrett!

ROTORHP

I'm actually feeling hopefull that I might fix my secondary grief now after reading this thread. I noticed today(finally had a 30° day) that my secondary wouldn't work when it was so hot outside.... then I read this!!! I have a check valve on order... now I think I will order me a solenoid valve as well Sure hope it cures it.... then on to the ACT clutch that is sitting on my table

tnblkbelt

Thanks for the suggestion...I will try anything at this point in time...Felt your frustration...been there...done that...

SleepR1

If all else fails, check your vacuum chamber. If it's full of oil, you will have no vacuum charge to work the turbo control actuator.

Herblenny

iTrader: (13)

Garrett, Thanks for the post.. I also have some issues with my secondary.. But its combination of not coming on and recently the whistling sound.. which I have never heard before.. I have just, I mean literally right before I was reading this, I got my engine all apart to do the simplification set up.. Damn.. If I youd of known this little earlier.. i guess I'll go head and do the simplification thing..

Thanks for the solution..

PHILIP SOHN