2nd Generation Specific (1986-1992) 1986-1992 Discussion including performance modifications and technical support sections.

No power at high rpms

Thread Tools
 
Search this Thread
 
Old Jan 15, 2003 | 01:19 PM
  #26  
Zach McAfee's Avatar
FTD Wanna Be
Tenured Member 10 Years
 
Joined: Jun 2002
Posts: 1,252
Likes: 0
From: Virginia
Originally posted by Net Seven
I just tested them with an air compressor. They go down and stay down real quick. They work get like that. Then that means that there is no pressure from the exhuast to make them open?? What do you guys think the problem is?
The air compressor has enough airflow to hold them open even if there is a leak. I would be carefull because who knows how much pressure the diaphragms in the actuators can take. A pump is better because you can keep the pressure low and monitor how much pressure is required.

If you can't get your hands on a pump, use the air compressor initially and then hold the line closed with your hand to make sure it holds the air. With the hand pump I could keep the actuators open, but as soon as I stopped pumping they would slowly slide back into place.

I don't know what your exhaust setup is, but I'm pretty sure you have enough backpressure with a street setup. Again, if you had a pressure gauge, you could measure exactly how much backpressure you have by hooking it up to the 6port feed line and running the motor up in RPMs.

I highly recommend running to the parts store and buying a nice vacuum/pressure pump with a guage on it. These are also nice for bleeding the brakes by yourself.
Reply
Old Jan 16, 2003 | 11:59 AM
  #27  
hugues's Avatar
Why am I here ?
Tenured Member 05 Years
 
Joined: May 2002
Posts: 671
Likes: 0
From: Boston, MA
To check if the cat is clogged, remove it an inspect the honeycomb. Clogged or damaged will be obvious.
Another way to check for a clogged exhaust (symptom: low power at high rpm, hard to start) is to:

connect a vacuum gauge to intake manifold

rev the engine to about 2,000-3,000

release throttle

manifold vacuum should rise for a short moment and then go back to normal quickly. If it is slow to react, there's an obstruction in the exhaust.

hugues -
Reply
Old Jan 16, 2003 | 07:45 PM
  #28  
Net Seven's Avatar
Thread Starter
Rotary Enthusiast
Veteran: Army
Tenured Member: 20 Years
Liked
iTrader: (5)
 
Joined: Apr 2002
Posts: 1,470
Likes: 15
From: Mesa, AZ
Well are they supposed to slowly go down after i stop putting pressure into the hose?
Reply
Old Jan 17, 2003 | 08:10 AM
  #29  
Zach McAfee's Avatar
FTD Wanna Be
Tenured Member 10 Years
 
Joined: Jun 2002
Posts: 1,252
Likes: 0
From: Virginia
Originally posted by Net Seven
Well are they supposed to slowly go down after i stop putting pressure into the hose?
No, that is exactly the problem. There is a leak. They should pull down and stay down.
Chances are you didn't remove all of the gasket material. Take off the actuators and completely clean everything and reinstall using gasket sealer just in case.
Reply
Old Jan 17, 2003 | 03:36 PM
  #30  
Net Seven's Avatar
Thread Starter
Rotary Enthusiast
Veteran: Army
Tenured Member: 20 Years
Liked
iTrader: (5)
 
Joined: Apr 2002
Posts: 1,470
Likes: 15
From: Mesa, AZ
So its fine to use that silicone gasket stuff on the aux ports? I guess I can do that... also how do i check to see if the actuall aux are good or not? I got extra ones laying around so I can put those on.
Reply
Old Jan 17, 2003 | 06:36 PM
  #31  
Full Member
Tenured Member 05 Years
 
Joined: Oct 2002
Posts: 157
Likes: 0
From: edmonton alberta
Are the actuators working if you get the 3800 rpm hesitation?
I have a streetported moter, nosats, no airpump and a header running thro 2 straight piepes which i think are 2 1/2 in diameter so are mine working?
I haven't reved past 5000 yet so im not sure. If their not what do i have to do to get them working again? Put on a new airpump?
Reply
Old Jan 18, 2003 | 02:22 AM
  #32  
Net Seven's Avatar
Thread Starter
Rotary Enthusiast
Veteran: Army
Tenured Member: 20 Years
Liked
iTrader: (5)
 
Joined: Apr 2002
Posts: 1,470
Likes: 15
From: Mesa, AZ
I just checked my aux ports by placing my thumb over the opening and it stays down so, its holding compression... Then I tried to blow into the hose and I couldnt get the ports down at all. Too hard to blow into. What do you guys think??? I know the problem is the ports not opening at 3800rpms because the grease donesnt get smeared.
Reply
Old Jan 18, 2003 | 11:01 AM
  #33  
Zach McAfee's Avatar
FTD Wanna Be
Tenured Member 10 Years
 
Joined: Jun 2002
Posts: 1,252
Likes: 0
From: Virginia
Originally posted by Net Seven
... so, its holding compression...
Ok, since there are no leaks you need to verify your exhaust is creating enough backpressure. You need a pressure gauge to do this.
... Then I tried to blow into the hose and I couldnt get the ports down at all. Too hard to blow into.
Your lungs will barely produce 1psi, which isn't enough. This only works on S5 actuators.
What do you guys think???
I think you'd be interested in this.
https://www.rx7club.com/forum/showth...hreadid=147853
As far as the stock system, there isn't much too it, so if you troubleshoot it from where the air goes in to where the valves move, you will find the problem. I screwed around with mine for 2 months before I figured it out. I was swappin **** out and not getting anywhere. When I started testing each part of the system I found my problem. Your problem, I don't know until you test every section. You do need a pressure gauge at this point to save any more hair pulling.

Buy me a plane ticket and I'll take a look at it.
Reply
Old Jan 18, 2003 | 11:07 AM
  #34  
Zach McAfee's Avatar
FTD Wanna Be
Tenured Member 10 Years
 
Joined: Jun 2002
Posts: 1,252
Likes: 0
From: Virginia
Originally posted by luv'n my 7
Are the actuators working if you get the 3800 rpm hesitation?
I have a streetported moter, nosats, no airpump and a header running thro 2 straight piepes which i think are 2 1/2 in diameter so are mine working?
I haven't reved past 5000 yet so im not sure. If their not what do i have to do to get them working again? Put on a new airpump?
The 3800 hesitation is another beast. Add a few more ground straps. You probably broke a few when you replaced the motor.
I'm assuming you have a S4. That exhaust system may not produce enough backpressure. The airpump has nothing to do with it unless you have a S5, in which you need the air pump but the system is almost flawless in that it does not depend on backpressure.
Read through this post if yours are not working.
Reply
Old Jan 18, 2003 | 02:18 PM
  #35  
Net Seven's Avatar
Thread Starter
Rotary Enthusiast
Veteran: Army
Tenured Member: 20 Years
Liked
iTrader: (5)
 
Joined: Apr 2002
Posts: 1,470
Likes: 15
From: Mesa, AZ
Ok, I need to know exactly how this system works. So far all i know is that backpressure from the exhuast line blows pressure into that hose and the aux ports go down. Is there any other vacume lines or anything like that, that could be leaking? When I said it wasnt leaking and was holding pressure I ment that I took the aux ports off the car and tested them not the stuff on the car.
Reply
Old Jan 18, 2003 | 05:00 PM
  #36  
MrFuzzy's Avatar
Damn Right It's Me
Tenured Member 10 Years
iTrader: (1)
 
Joined: Jan 2003
Posts: 1,331
Likes: 0
From: Chino Hills, Cali
If the Cat is clogged would it affect smog testing?
Reply
Old Jan 18, 2003 | 05:08 PM
  #37  
Net Seven's Avatar
Thread Starter
Rotary Enthusiast
Veteran: Army
Tenured Member: 20 Years
Liked
iTrader: (5)
 
Joined: Apr 2002
Posts: 1,470
Likes: 15
From: Mesa, AZ
Ok i have now just tested it while it was all attached with an air compressor. I put 10psi into the line and the ports slowly went down, then when the pressure stops they go up really fast. I even tried to kink the hose while they were down to see if the pressure went back into the the air compressor or something, and same exact thing they just go back up really fast.

So right now i know that I need a lot more psi to get them down then they are supposed to be getting, and they dont stay down at all. An air leak somewhere you think?? Its not the aux ports, i just tried swaping them and stuff like that, and same exact thing... I also have new gaskets on them, and yes i did take off the old gasket very well.

Some please help, my car seems like a slow POS.
Reply
Old Jan 18, 2003 | 05:40 PM
  #38  
Net Seven's Avatar
Thread Starter
Rotary Enthusiast
Veteran: Army
Tenured Member: 20 Years
Liked
iTrader: (5)
 
Joined: Apr 2002
Posts: 1,470
Likes: 15
From: Mesa, AZ
I am thinking maybe I should take the intake manifold off and everything like that and clean the ports, and replace all the hoses. I think that I have a leak somewhere in the hoses causing my ports not to work. How much hose of what size will I need and what gaskets and other things would I need to do this job?
Reply
Old Jan 19, 2003 | 09:50 AM
  #39  
Zach McAfee's Avatar
FTD Wanna Be
Tenured Member 10 Years
 
Joined: Jun 2002
Posts: 1,252
Likes: 0
From: Virginia
Ok so you do have a leak. Try spraying windex everywhere and then put air to it. It will bubble up where your leak is. I don't think you need to remove your whole intake.
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Queppa
New Member RX-7 Technical
11
Nov 18, 2024 03:47 AM
distr0
Megasquirt Forum
48
Mar 18, 2022 06:17 PM
Skeese
Adaptronic Engine Mgmt - AUS
65
Mar 28, 2017 03:30 PM
stickmantijuana
Microtech
30
Apr 23, 2016 06:37 PM




All times are GMT -5. The time now is 12:19 PM.