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

Injector causing vac leak?

Thread Tools
 
Search this Thread
 
Old Feb 5, 2006 | 11:11 PM
  #1  
mr0pistons's Avatar
Thread Starter
Bird Dog
Tenured Member 05 Years
 
Joined: Sep 2003
Posts: 795
Likes: 0
From: St. Louis MO
Injector causing vac leak?

I think I have finally sourced my problem. I started the car up and it revved to 5k really fast then slowly climbed until I shut it off. When it was going my friend said he heard some noise coming from under/around the UIM. So I had him crank it with the gas pedal to the floor so it wouldn't start. I heard it coming from what I am positive is one of the secondary injectors. I have never dealt with injectors before, have never removed or taken them out so I don't know how they are supposed to be seated. But when I had the manifold off I noticed the injector in question could spin pretty easily. The other one was pretty secure though. Is this my problem? What could be causing it to act like this?(the injector, not the car)
Reply
Old Feb 5, 2006 | 11:21 PM
  #2  
HAILERS's Avatar
HAILERS
Tenured Member 10 Years
 
Joined: May 2001
Posts: 20,563
Likes: 27
From: FORT WORTH, TEXAS,USA
There are rubber grommets at the bottom of each injector. If they are old they get rock hard and are a potential air leak/vacuum leak. Normal fuel injectors will move back and forth with light finger pressure.
Reply
Old Feb 5, 2006 | 11:22 PM
  #3  
mr0pistons's Avatar
Thread Starter
Bird Dog
Tenured Member 05 Years
 
Joined: Sep 2003
Posts: 795
Likes: 0
From: St. Louis MO
So it's a damn good chance this is what's causing my problem?
Reply
Old Feb 6, 2006 | 01:13 AM
  #4  
n/a-luvr's Avatar
certified nutz and boltz
Tenured Member 05 Years
 
Joined: Jan 2006
Posts: 230
Likes: 0
From: myrtle beach, sc
Did I give you advice before? Don't remember but anyways the kits to repack the injectors are $8 per injector at advance - they have to be ordered so prepare to wait a day. Just replaced mine last week; the rubber had become so hard, I had to drill them off! I also replaced the LIM/UIM gasket. The result?

MUCH BETTER, the idle has improved, driveability has increased, purrs instead of growls (which is a good thing in this instance). Cheap investment for an older car.

However, they normally don't so bad that you can definitely hear them unless you've removed them and put them back together with the same old or broken seals. Are you positive you don't have a vacuum hose disconnected? I had a huge leak after reassembly and it was one of the hoses that connects to the back of the UIM by the throttle cable. It was tricky to find cause the noise was reflecting off the firewall making the leak sound like it was coming from the secondary injector area. Hold a clean funnel to your ear to pinpoint the leak. ~rich
Reply
Old Feb 6, 2006 | 09:02 AM
  #5  
HAILERS's Avatar
HAILERS
Tenured Member 10 Years
 
Joined: May 2001
Posts: 20,563
Likes: 27
From: FORT WORTH, TEXAS,USA
Originally Posted by mr0pistons
So it's a damn good chance this is what's causing my problem?
If you didn't remove them, I don't see them being your problem. The problem usually arises when someone removes them and then reinstalls them and cracks one of them on reinstallation.

If you removed the primary fuel rail and reinstalled it, then it's possible that you got the injectors in a touch crooked and cracked a old lower grommet and caused a air leak.

If you did not do that, then I'd re-read the post above this one by na-luvr.

A engine that starts up and the rpms keep climbing above 5000 makes me think something has the throttle plates jammed a touch open. I'd take a look at the plates and see if they are cracked open a touch. They should be closed all the way with the engine off.

Welllllll there's an exception to the above with a cold engine. The waterthermowax will have the primary plate cracked open a touch. You'd have to lift up on the thermowax linkage to disengage that thermowax to make the primary plates go to full close.
Reply
Old Feb 6, 2006 | 09:45 AM
  #6  
mr0pistons's Avatar
Thread Starter
Bird Dog
Tenured Member 05 Years
 
Joined: Sep 2003
Posts: 795
Likes: 0
From: St. Louis MO
I did remove them, I was going to put 720's in but they were the wrong injectors. I'll get some grommets for them and try that. I'll check out the throttle plates too.
Reply
Old Feb 8, 2006 | 12:44 AM
  #7  
mr0pistons's Avatar
Thread Starter
Bird Dog
Tenured Member 05 Years
 
Joined: Sep 2003
Posts: 795
Likes: 0
From: St. Louis MO
Well, I fixed the injector problem. My dumbass had two grommets on the bottom for some reason Now instead of starting and revving up and up, it just fires like it should but dies right away, any thoughts? I wasn't able to get enough tries to get it to work because the battery pooped on me. I'll try tomorrow with a charger and see what happens.
Reply
Old Feb 8, 2006 | 01:06 AM
  #8  
n/a-luvr's Avatar
certified nutz and boltz
Tenured Member 05 Years
 
Joined: Jan 2006
Posts: 230
Likes: 0
From: myrtle beach, sc
Dies like something has killed fuel or spark or dies like something is set too low? There is a HUGE difference between the two as the former will go from rpm to stop quickly and smoothly while the latter will cough and sputter somewhat as the engine gets close to stopping. ~rich
Reply
Old Feb 8, 2006 | 01:43 AM
  #9  
mr0pistons's Avatar
Thread Starter
Bird Dog
Tenured Member 05 Years
 
Joined: Sep 2003
Posts: 795
Likes: 0
From: St. Louis MO
Starts up like its going to the 3k and shuts off. It doesn't cough or sputter, just dies. goddammit. I think it has to do with the connection between the UIM and LIM. I need to get my hands on a gasket. ****** carquest doesn't carry the sumbitches, so i just winged it to see if it would work. obviously not.
Reply
Old Feb 8, 2006 | 01:45 AM
  #10  
mr0pistons's Avatar
Thread Starter
Bird Dog
Tenured Member 05 Years
 
Joined: Sep 2003
Posts: 795
Likes: 0
From: St. Louis MO
Also, I don't think it will start without having my foot on the gas a little bit. Any thoughts on that? Perhaps it is linked with the leak at the manifold?
Reply
Old Feb 8, 2006 | 09:20 AM
  #11  
n/a-luvr's Avatar
certified nutz and boltz
Tenured Member 05 Years
 
Joined: Jan 2006
Posts: 230
Likes: 0
From: myrtle beach, sc
Originally Posted by mr0pistons
Also, I don't think it will start without having my foot on the gas a little bit. Any thoughts on that? Perhaps it is linked with the leak at the manifold?
Yup, running too lean. Your foot on the gas is giving enough TPS input to increase fuel to the point where it'll run. ~rich
Reply
Old Feb 8, 2006 | 09:29 AM
  #12  
DemonicPupil's Avatar
AutoX Donut Maker
Tenured Member: 20 Years
 
Joined: Feb 2005
Posts: 792
Likes: 1
From: Annville, PA
I think it's more like he didn't plug his BAC back in. Look under your intake piping and see if a 3/4" ish hose is not plugged in. If fit's not, it'll fire up and die every single time.
Reply
Old Feb 8, 2006 | 02:34 PM
  #13  
mr0pistons's Avatar
Thread Starter
Bird Dog
Tenured Member 05 Years
 
Joined: Sep 2003
Posts: 795
Likes: 0
From: St. Louis MO
Originally Posted by DemonicPupil
I think it's more like he didn't plug his BAC back in. Look under your intake piping and see if a 3/4" ish hose is not plugged in. If fit's not, it'll fire up and die every single time.
The one that goes to the charge pipe between the turbo and IC, yea it's plugged in. Although the plug that plugs into the BAC has definitely seen better days.
Reply
Old Feb 8, 2006 | 04:30 PM
  #14  
JoshRX7's Avatar
Senior Member
Tenured Member 10 Years
iTrader: (5)
 
Joined: Jul 2005
Posts: 556
Likes: 1
From: Louisville, KY
You've got a pretty big vacuum leak somewhere it sounds like...
Reply
Old Feb 8, 2006 | 04:40 PM
  #15  
InMyWhiteTII's Avatar
We are the D
Tenured Member 05 Years
 
Joined: Nov 2005
Posts: 492
Likes: 0
From: Indianapolis
I think me, you, and JoshRX7 all need to get together and find out what the hell is wrong with our cars. Damn vacuum leaks are killing me
Reply
Old Feb 8, 2006 | 05:29 PM
  #16  
NOPR's Avatar
Rotary Apprentice
Tenured Member 15 Years
 
Joined: Jan 2005
Posts: 2,181
Likes: 0
From: USA
i assume you took off the UIM to get to the injector, did you completely (COMPLETELY) remove the old gasket and put on a new one?
Reply
Old Feb 8, 2006 | 11:34 PM
  #17  
mr0pistons's Avatar
Thread Starter
Bird Dog
Tenured Member 05 Years
 
Joined: Sep 2003
Posts: 795
Likes: 0
From: St. Louis MO
Originally Posted by InMyWhiteTII
I think me, you, and JoshRX7 all need to get together and find out what the hell is wrong with our cars. Damn vacuum leaks are killing me
+1

I just found a crack in the LIM. **** YEA!!!!! I think that is my problem.
Reply
Old Feb 9, 2006 | 10:55 PM
  #18  
JoshRX7's Avatar
Senior Member
Tenured Member 10 Years
iTrader: (5)
 
Joined: Jul 2005
Posts: 556
Likes: 1
From: Louisville, KY
First time I've ever heard excitement over a cracked manifold... haha. Hope you found your problem... however, get that screwdriver and carb cleaner out and tighten everything up for sure

Josh
Reply
Old Feb 10, 2006 | 12:40 PM
  #19  
mr0pistons's Avatar
Thread Starter
Bird Dog
Tenured Member 05 Years
 
Joined: Sep 2003
Posts: 795
Likes: 0
From: St. Louis MO
Originally Posted by JoshRX7
First time I've ever heard excitement over a cracked manifold... haha. Hope you found your problem... however, get that screwdriver and carb cleaner out and tighten everything up for sure

Josh
Ha, it was more sarcasm. I'm really not that excited at all.
Reply
Old Feb 10, 2006 | 12:52 PM
  #20  
n/a-luvr's Avatar
certified nutz and boltz
Tenured Member 05 Years
 
Joined: Jan 2006
Posts: 230
Likes: 0
From: myrtle beach, sc
I got an '87 s4 n/a LIM on my parts car if you need one... ~rich
Reply
Old Feb 10, 2006 | 03:16 PM
  #21  
ilike2eatricers's Avatar
I R SAD PANDA W/O BAW
 
Joined: Nov 2002
Posts: 6,061
Likes: 1
From: bay area
how do you get a crack in a stock intake manfiold??
Reply
Old Feb 10, 2006 | 03:21 PM
  #22  
Juiceh's Avatar
Saiga-12 Power!
Tenured Member: 20 Years
iTrader: (4)
 
Joined: Oct 2004
Posts: 4,385
Likes: 2
From: N of Chicago
I had an S4 NA LIM crack on me.. it happens. I have a S5 TII LIM if you need it mr0pistons.
Reply
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
trickster
2nd Generation Specific (1986-1992)
25
Jul 1, 2023 04:40 PM
rotor_veux
2nd Generation Specific (1986-1992)
5
Sep 3, 2015 07:10 PM
Donald Hampton
New Member RX-7 Technical
7
Sep 1, 2015 03:41 AM




All times are GMT -5. The time now is 09:34 AM.