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)

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.

So it's a damn good chance this is what's causing my problem?

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

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.

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.

Well, I fixed the injector problem. My dumbass had two grommets on the bottom for some reason :dunno: 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. :wallbash: :wallbash:

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

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. Fuckin carquest doesn't carry the sumbitches, so i just winged it to see if it would work. obviously not.

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

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.

You've got a pretty big vacuum leak somewhere it sounds like...

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

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?

+1

I just found a crack in the LIM. FUCK YEA!!!!! I think that is my problem.

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.

I got an '87 s4 n/a LIM on my parts car if you need one... ~rich

how do you get a crack in a stock intake manfiold??

I had an S4 NA LIM crack on me.. it happens. I have a S5 TII LIM if you need it mr0pistons.