Need a service-manual scan of EGR (94-97) - Miata Turbo Forum - Boost cars, acquire cats.

General Miata Chat A place to talk about anything Miata

Need a service-manual scan of EGR (94-97)

Old 10-31-2012, 04:43 PM
  #1  
Boost Pope
Thread Starter
iTrader: (8)
 
Joe Perez's Avatar
 
Join Date: Sep 2005
Location: Chicago. (The non-murder part.)
Posts: 27,962
Total Cats: 2,446
Default Need a service-manual scan of EGR (94-97)

I am looking for a diagram of the vacuum side of the EGR system in a '94-'97 car. The EGR valve diaphragm, the vent/vacuum solenoids, and the functional path between them.

Any chance one of you faeries can hook me up?
Joe Perez is offline  
Old 10-31-2012, 06:06 PM
  #2  
Elite Member
iTrader: (21)
 
Join Date: Jun 2007
Location: Rochester, NY
Posts: 6,000
Total Cats: 768
Default

Sorry, just checked and my Haynes doesn't have any diagrams.
rleete is offline  
Old 10-31-2012, 06:10 PM
  #3  
Boost Pope
Thread Starter
iTrader: (8)
 
Joe Perez's Avatar
 
Join Date: Sep 2005
Location: Chicago. (The non-murder part.)
Posts: 27,962
Total Cats: 2,446
Default

A pox on your Haynes manual. (And the one I just ordered off of eBay for $1.99 plus $3.99 shipping.)
Joe Perez is offline  
Old 10-31-2012, 06:21 PM
  #4  
Newb
 
Join Date: Sep 2011
Location: Texas
Posts: 18
Total Cats: 3
Default

tobimaru is offline  
Old 10-31-2012, 06:26 PM
  #5  
Elite Member
iTrader: (21)
 
Join Date: Jun 2007
Location: Rochester, NY
Posts: 6,000
Total Cats: 768
Default

Props to you, sir.
rleete is offline  
Old 10-31-2012, 06:42 PM
  #6  
Boost Pope
Thread Starter
iTrader: (8)
 
Joe Perez's Avatar
 
Join Date: Sep 2005
Location: Chicago. (The non-murder part.)
Posts: 27,962
Total Cats: 2,446
Default

Props indeed, that is precisely what I was looking for!



From looking at pictures of the actual parts, it appeared that the two solenoid valves were plumbed in series, and I thought "That's stupid- I must be looking at this wrong." This confirms that they are, in fact, in series.

So that, of course, raises the question in my mind: Why the heck did they bother having two solenoids when it would seem that one would suffice?

With a single solenoid of the type on the right, the ECU would be able to select between atmosphere or manifold vacuum. The only thing that adding the second solenoid does is to enable the selection of a third state: sealed off from both atmosphere and manifold vacuum.

What possible purpose can there be to such an arrangement?
Attached Thumbnails Need a service-manual scan of EGR (94-97)-egr.gif  
Joe Perez is offline  
Old 10-31-2012, 09:19 PM
  #7  
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 75,089
Total Cats: 2,114
Default

looks like ones a two and way and ones a three way/
Braineack is offline  
Old 10-31-2012, 09:26 PM
  #8  
Tour de Franzia
iTrader: (6)
 
hustler's Avatar
 
Join Date: Jun 2006
Location: Republic of Dallas
Posts: 29,085
Total Cats: 367
Default

Originally Posted by Joe Perez View Post
Props indeed, that is precisely what I was looking for!
1351719430[/IMG]

From looking at pictures of the actual parts, it appeared that the two solenoid valves were plumbed in series, and I thought "That's stupid- I must be looking at this wrong." This confirms that they are, in fact, in series.

So that, of course, raises the question in my mind: Why the heck did they bother having two solenoids when it would seem that one would suffice?

With a single solenoid of the type on the right, the ECU would be able to select between atmosphere or manifold vacuum. The only thing that adding the second solenoid does is to enable the selection of a third state: sealed off from both atmosphere and manifold vacuum.

What possible purpose can there be to such an arrangement?
More reason to put them in the garbage...or come up with a way to run EGR to increase fuel economy on my daily, and spell it out for me like I have the brain of a child.
hustler is offline  
Old 11-01-2012, 01:41 AM
  #9  
Boost Pope
Thread Starter
iTrader: (8)
 
Joe Perez's Avatar
 
Join Date: Sep 2005
Location: Chicago. (The non-murder part.)
Posts: 27,962
Total Cats: 2,446
Default

Originally Posted by hustler View Post
More reason to put them in the garbage...
Or to retrofit EGR into a vehicle which did not originally have it (such as 1990 Miata with an NB engine in it) for the purpose of running E85 in a high-compression configuration and yet still being able to pass a California emissions test.


Incidentally, who the hell is that girl in your avatar?
Joe Perez is offline  
Old 11-01-2012, 09:49 AM
  #10  
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 75,089
Total Cats: 2,114
Default

How do you not know who Taylor Swift is? honestly.


I have a feeling the 2-way solenoid is an on/off, to simply open the EGR fully. Then the 3-way is a pwm signal to control the amount of flow. Why they couldn't have just used one is beyond me. But then again I'm just guessing.
Braineack is offline  
Old 11-01-2012, 10:21 AM
  #11  
Newb
 
Join Date: Sep 2011
Location: Texas
Posts: 18
Total Cats: 3
Default

Originally Posted by Joe Perez View Post
Props indeed, that is precisely what I was looking for!


Found using Google images surprisingly. I saw the diagram and it was the right year and everything!
Attached Thumbnails Need a service-manual scan of EGR (94-97)-i-hate-sandcastles-_-success-kid-know-your-meme.jpg  
tobimaru is offline  
Old 11-01-2012, 10:27 AM
  #12  
Tour de Franzia
iTrader: (6)
 
hustler's Avatar
 
Join Date: Jun 2006
Location: Republic of Dallas
Posts: 29,085
Total Cats: 367
Default

Originally Posted by Joe Perez View Post
Incidentally, who the hell is that girl in your avatar?
One of my blondes.
hustler is offline  
Old 11-01-2012, 10:32 AM
  #13  
Boost Czar
iTrader: (61)
 
Braineack's Avatar
 
Join Date: May 2005
Location: Chantilly, VA
Posts: 75,089
Total Cats: 2,114
Default

Originally Posted by hustler View Post
One of my blondes.
She's kinda Chicken-headin' it as of late.

Are you John Mayer?
Braineack is offline  
Old 11-01-2012, 01:50 PM
  #14  
Boost Pope
Thread Starter
iTrader: (8)
 
Joe Perez's Avatar
 
Join Date: Sep 2005
Location: Chicago. (The non-murder part.)
Posts: 27,962
Total Cats: 2,446
Default

Originally Posted by Braineack View Post
I have a feeling the 2-way solenoid is an on/off, to simply open the EGR fully. Then the 3-way is a pwm signal to control the amount of flow.
Hmm.

I'm torn here. PWMing the solenoid which is connected to the VTA would potentially introduce a vacuum leak into the system when the other solenoid was open.

On the other hand, PWMing the solenoid which is connected to the manifold would accomplish nothing, assuming that the other solenoid was fully open in the non-VTA position. (Regardless of PWM, the vacuum at the diaphragm would very quickly equalize at manifold pressure in the absence of a bleed, and I don't see a bleed anywhere in the system.)

Does the ECU in fact PWM this signal? I kind of assumed that since the EGR valve itself was vacuum-operated, that the position of the diaphragm would tend to automatically be proportional to manifold vacuum.

On the other hand, the presence of the EGR valve position sensor even in the pre-OBD II cars does suggest closed-loop operation.

I really wish I had a '94 - '97 car here to examine. Or at least a '94-'97 EGR valve to experiment with.
Joe Perez is offline  
Old 11-01-2012, 03:05 PM
  #15  
Elite Member
iTrader: (21)
 
Join Date: Jun 2007
Location: Rochester, NY
Posts: 6,000
Total Cats: 768
Default

Fly out to Rochester. You can inspect my system to your heart's desire.
rleete is offline  
Old 11-01-2012, 03:16 PM
  #16  
Boost Pope
Thread Starter
iTrader: (8)
 
Joe Perez's Avatar
 
Join Date: Sep 2005
Location: Chicago. (The non-murder part.)
Posts: 27,962
Total Cats: 2,446
Default

Originally Posted by Braineack View Post
How do you not know who Taylor Swift is? honestly.
Simple- I'm not a 13 year old girl. (I had to use Wikipedia to find out who Taylor Smith even was.)

Originally Posted by rleete View Post
Fly out to Rochester. You can inspect my system to your heart's desire.
Yeah, about that...

No.
Joe Perez is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Corky Bell
Prefabbed Turbo Kits
18
11-22-2016 10:01 PM
curly
MEGAsquirt
11
09-22-2015 12:54 PM
hdizzle
Meet and Greet
8
09-21-2015 11:08 AM
Heyitsryan
WTB
0
09-12-2015 09:47 PM
sharkythesharkdogg
WTB
7
09-06-2015 02:40 PM


Quick Reply: Need a service-manual scan of EGR (94-97)


Archive Advertising Cookie Policy Privacy Statement Terms of Service

© 2018 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.