My issue is I am not getting boost at all but I,m not getting out of VACUUM at all when accelerating!
Running full open exaust,pfc and sequential,ported motor.
I have checked the vac lines,found 7 leaks in the hoses and replaced them,pulled the couplers inside out changed the stock bov around,had the uim off 3 times looking for the smoking gun,compression tasted ok,motor runs fine.
So where would you look next?solenoids? would you not expect even a few psi? even with a bad one?
I would love some input before we go tear into anything else,thanks.

 

What does it feel/sound/smoke/stutter like when you're on the throttle and it's maxing out at 0psi?

Does the MAP reading in the PFC match the boost gauge?

How's your TPS reading?

Dave

 

does a whissling sound comes when you rev it up ??

Con

 

Engine itself feels and sounds normal,there is a small change in intake pitch at the 4500 rpm change over point,it sounds like something is blocking something preventing the flow.As the revs rise the vacuum gauge never makes it out of vacuum to boost and the motor feels choked.
Yes my map reading on the pfc is matches my boost guage.
I have not checked my tps reading directly,can I do this via the pfc? thanks,Carl.

 

[QUOTE=mp5]Engine itself feels and sounds normal,there is a small change in intake pitch at the 4500 rpm change over point,it sounds like something is blocking something preventing the flow.As the revs rise the vacuum gauge never quite makes it to boost and the motor feels choked more in the higher rpm range where boost should be.
Yes my map reading on the pfc is matches my boost guage.
I have not checked my tps reading directly,can I do this via the pfc? thanks,Carl.

 

Rx7maniac13b. no whistling sound

 

Check your wastegate and precontrol actuator arms to make sure the small e-clips have not come off, leading to the arms dangling freely and not attached to the flapper doors like they should be. You'll need to jack up the front passenger side of the car and get under there with a flashlight to look around.

 

It could be so many things. The worst being your turbos are gone. How many mile are on them. Aslo try boosting with the hood up and intake taken off. See if the boost comes back out of one of the intake tubes. I have seen a set that had one bad turbo and the good one just blew its boost out through the other one.

 

Thank you for your suggestion, I have had a good look at the precontrol arms they are all attached,I removed the e-clip from the wastegate flapper it moves freely back and forth,as for the actuators?do they stick open/closed?

 

Interesting idea..87,000 miles on the turbos...it would not be a big suprise if they are gone,however there was no oil on the turbos when I looked underneath and they were boosting fine post boost leak fix.After the leaks are fixed the turbos fail to work?just coincidence?
I,m not quite ready to write the twins off yet and still think it is a control issue of some sort.

 

Your turbos are almost positively fine.

This is almost always a control problem. The valves controlling exhaust and/or intake flow are probably not operating properly. Goodfella's idea of checking the actuator arms is a good start.

Anyway, solving a boost problem takes patience since there are many possible failure points. The fix is usually cheap. The trick is to start with the basics. Boost leaks, loose vacuum hoses, disconnected actuator arms, and bad check valves are perfect starting points. If you're lucky, it'll be something visual and simple. I think you hit those items already, but you didn't mention check valves.

Next step is the KOKO test - http://www.fd3s.net/boost_test.html. If you let us know the results that gives the rest of the troubleshooting some direction.

Dave

 

Check the double throttle, make sure the butterflies are not stuck shut.

 

[B]Hey guys, I'm new and from the sound of it, my FD is having a similar problem. I bought it about 4 months ago. It had a new engine w/ 5k but the turbos were original and now have 90,000k on them. the car has been very good and has had no problems until just last weekend. I was driving and my RPM range went from 2,000 to like 4,500 in like one second, almost like it just skipped the primary turbo. the boost was quivering at 10psi and I could hear it spool but it sounded really bad and there was a huge loss of horsepower. I have nobody down here to help me! theres only like 3 ppl down here that even have FD's and they cant help either. im in VA and short of going to peter farrell and getting charged an arm and a leg for a diagnostic, I dont know what to do. I dont know a lot about these cars and I really need help.

 

SevenTT, it seems you have a slipping clutch. RPMs cant change that fast unless the tires are spinning.

Dave

 

[B]It's an automatic. and I think the tires are spinning but it's like I can be flooring it and the engine is roaring but i'm only going like 25mph.

 

[B]Okay, when I'm driving, if I slowly and I mean slowly accelerate, the rpm's wont shoot up very far but if I'm accelerating fast, or even normally, they will and the engine roars. it even occasionally stalls on me.

 

[B][B]It sounds similar is what MP5's is doing. I dont know?!

 

[QUOTE=dgeesaman][font=Arial]Your turbos are almost positively fine.

This is almost always a control problem. The valves controlling exhaust and/or intake flow are probably not operating properly. QUOTE]

Valves? are you referring to the wastegate and turbo pre control actuators? it looks like they work on pressure?everything checks visually,as does the turbo control actuator underneath,I put the mighty vac on the larger of the two hoses and the rod moves freely back and forth.

 

[QUOTE=mp5]I'm referring to the turbo control valve, charge control valve, charge relief valve, and air bypass valve. The wastegate and precontrol valves operate on pressure, yes.

I suggest running the KOKO test I linked before, and also doing a couple of runs with the air bypass valve disconnected from your intake. Also do the same with the charge relief valve disconnected from your intake. The air bypass should not make the sound of venting air when you're trying to boost. The charge relief should not vent after 4500rpm.

Another thought - does the car have any trouble revving up to 0psi? Or does it struggle a little bit just to get out of vacuum?

Dave

 

I did most of the koko that I can do solo just to get started(freind coming over tomorrow can look for the charge and turbo control actuators moving)
I did see the charge control actuator move back out when the turbo timer shut off.
Ok this is what I have so far my vacuum reads 10inhg engine running at normal operating temperature,I have pretty good streetport.
Wot in neutral did not give me any psi at all,at this point I,m under the hood and again go wot and do not see the precontrol rod move at all.
Removing the hose at the charge releif actuator,nothing happened,no air escaping at all,I can confirm that the charge control actuator rod is in when motor is running and out when motor is shut off.The pressure tank does release air when I remove the front hose with the motor off.
And yes the motor does have trouble revving up to 0 psi.In fact it is not getting out of vacuum.

 

Maybe that's the key issue. If you had a boost leak of any kind or open control valve, I would expect it would easily get to 0 but no further.

If you're having trouble revving to 0psi, that suggests something else.

Is there any possibility you have something clogging your exhaust?

Dave

 

sounds like your auto tranny needs a rebuild or i would suggest ditching that worthless pos and putting a manual in it.

 

auto tranny guy: it really sounds like your transmission is slipping.

To the OP: CHECK YOUR DOUBLE THROTTLE ASSEMBLY, it sounds to me like the secondaries are not opening. No throttle = like your foot isn't on the gas = slowass car and impossible to get out of vacuum.

but that may not be the only problem, even with 1/3 throttle the turbo should spool.

 

Ok I managed to get a set of used solenoids most of them check out blowing by blowing air through b-c port test,thankfully I have a brand new switching solenoid that will work as a replacement for the broken double throttle control solenoid so I will dig into this tomorrow and give a update.
Two things,first I need to generate 7 psi to operate the solenoids?hopefully this solves that.
I know of 3 or 4 that I replaced less than 2 years ago so I may just be unlucky.
Second,a year and a half old vacuum hose job with viton has revealed 8 splits and holes(my fualt being clumsy) not one has popped off at and the integrity of the viton feels as good as new,but if your working on fixing your motor,and who isnt you may want to check yours.

 

If there is any way you can use a Mityvac to test the solenoids before putting them in, I strongly recommend that. Mileage or simple click tests are insufficient to find sticking solenoids, which can be pretty difficult to diagnose any other way.

If you choose to buy a Mityvac - get the Silverline Plus kit. Money well invested if you plan to keep the stock sequential setup.

Dave