How do I find a leaking injector?
#2
Yes, it's called the injector balance test. The injector balance test checks the injector in the car. You disconnect the injector harness from all the injectors, hook up a fuel pressure gauge, and use this injector testor which hooks up to an injector (in place of the harness) and you fire off the injector at your control. You measure the pressure before and after, repeat for all injectors. If one or more injector is bad, it's variance will be more then 10kPa compared to the other injectors.
Before you do that, check the injector resistance first. It'll probably be much faster to do that.
Before you do that, check the injector resistance first. It'll probably be much faster to do that.
#3
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Car: 1989 Iroc
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One of the ways i read about in one of the Automotive repair manuels was to pull the fuel rails, and put a peice of paper under each injector, then turn the key to prime the fuel pump. Any injectors leaking will drip gas onto the paper, and *bam* you have your leaky injectors. Its probably a good idea to take all the proper percautions when working around the fuel system. Just had to mention that for safty.
Laters,
Joker
Laters,
Joker
#4
Supreme Member
I don't see how an "injector balance test" is going to tell you anything other than that you've got injectors leaking. You fire off an injector and the pressure drops a certain amount based on how much it's fired, but if you've got injectors leaking it's been dropping ever since there was fuel in the rails. Pressure will bleed off no matter what if you've got a bad injector, so doing this won't at all let you isolate the problem. Pulling the fuel rail and priming the pump to watch for a drip seems easier and more reliable.
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subject
Is there an easier way to get the retaining clips off and on the injector harnesses? It took me forever to access and test and re-clip the easiest one. I can't even imagine getting at the buried ones...
#6
Originally posted by rezinn
I don't see how an "injector balance test" is going to tell you anything other than that you've got injectors leaking. You fire off an injector and the pressure drops a certain amount based on how much it's fired, but if you've got injectors leaking it's been dropping ever since there was fuel in the rails. Pressure will bleed off no matter what if you've got a bad injector, so doing this won't at all let you isolate the problem. Pulling the fuel rail and priming the pump to watch for a drip seems easier and more reliable.
I don't see how an "injector balance test" is going to tell you anything other than that you've got injectors leaking. You fire off an injector and the pressure drops a certain amount based on how much it's fired, but if you've got injectors leaking it's been dropping ever since there was fuel in the rails. Pressure will bleed off no matter what if you've got a bad injector, so doing this won't at all let you isolate the problem. Pulling the fuel rail and priming the pump to watch for a drip seems easier and more reliable.
Like I said, check the injector resistance first. Hook up an ohmmeter to the 2 nodes of the electrical connector of the injector. Depending on the injector, the resistances are usually 12 or 15-16 ohms for GM injectors. The resistances should be matched within a small variance. To determine your injector resistance, use a dental mirror, wipe off the top sides of the injector and look for the imprint, and search for the injector stats.
If the resistance is OK, then try the injector balance test.
Last edited by 91Z28-350; 03-10-2003 at 10:05 PM.
#7
Re: subject
Originally posted by Svelte_SS
Is there an easier way to get the retaining clips off and on the injector harnesses? It took me forever to access and test and re-clip the easiest one. I can't even imagine getting at the buried ones...
Is there an easier way to get the retaining clips off and on the injector harnesses? It took me forever to access and test and re-clip the easiest one. I can't even imagine getting at the buried ones...
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#10
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OK, the TPS, IAC etc is all set right.. new O2.. the problem is even with everything set properly I still get a bit of a rough idle and horrible gas mileage. Throttle response is a little jerky, and when I leave the car in the garage it smells like fuel later on
I get about 12-14mpg overall when others have seen 5+ mpg more
When I got the car it wasn't running close to how it should, and it feels like i've almost got it there, but not quite...
OH yeah, I don't know if it's the scanner or what but when I hook the scanner up and plug in any variable, like 02 voltage, it refreshes the number like once every 3 seconds.. on my other tpi cars it used to update the number a few times a second
I get about 12-14mpg overall when others have seen 5+ mpg more
When I got the car it wasn't running close to how it should, and it feels like i've almost got it there, but not quite...
OH yeah, I don't know if it's the scanner or what but when I hook the scanner up and plug in any variable, like 02 voltage, it refreshes the number like once every 3 seconds.. on my other tpi cars it used to update the number a few times a second
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Car: 2008.5 Mazdaspeed 3 GT
Engine: 2.3 DISI Turbo
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I just replaced all of my vacuum hoses hoping that I wouldn't have to pull the injectors for just about the same issue RE: poor MPG. I gained 1-2 MPG back, but everything else is good up to this point. I've changed the O2, checked for gasket leaks, etc. Looks like the only thing left is the injectors themselves.
My injectors check out fine electrically. That means a good cleaning *should* clear them up if the internal seals aren't worn to badly. I'll be using the DIY method posted by a thirdgen.org member here a while back.
My injectors check out fine electrically. That means a good cleaning *should* clear them up if the internal seals aren't worn to badly. I'll be using the DIY method posted by a thirdgen.org member here a while back.
#14
Supreme Member
I see. That seems like a lot of work to just see that you've got an injector leaking. Why don't you just pinch off the return line, prime the pump, and check to see if pressure drops? That will take maybe five minutes.
As far as your problem, it may be a combination of things. Leaking injectors could very well contribute. See any gas puddles under the car? If you drive with a lead foot, 14mpg may be good for you.
As far as your problem, it may be a combination of things. Leaking injectors could very well contribute. See any gas puddles under the car? If you drive with a lead foot, 14mpg may be good for you.
#15
Yes, that's true. Pinching off would work, though I've not done that. How do you pinch it off? Remove the return fuel line and cap it, or just put a clamp on the rubber return hose? I kind of need to do this particular test, because I just noticed my fuel pump priming and awfully lot when I had to toggle ignition switch for some work I was doing. I hooked up my fuel guage and it doesn't maintain pressure. I don't think I have a fuel leak, no smells, no droplets, and I don't think my injectors are bad. The drop is very fast, and seems too fast for a leaky injector and a smooth running injector. It seems like my fuel pump check valve may be shot, so I need to check that.
GM injectors are worth something, as they aren't exactly cheap from the dealer. Finding the bad one may be worth it, for selling the remaining good ones to someone on e-bay.
GM injectors are worth something, as they aren't exactly cheap from the dealer. Finding the bad one may be worth it, for selling the remaining good ones to someone on e-bay.
#16
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Car: '91 Z28
Engine: L98 5.7L TPI
Transmission: 700R4
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Originally posted by 91Z28-350
...Pulling the fuel rail is quite a bit of work just to see if the injectors are a problem. You've got to pull the plenum and runners and clean all the gaskets, replacing the gaskets, and most likely the o-rings too...
...Pulling the fuel rail is quite a bit of work just to see if the injectors are a problem. You've got to pull the plenum and runners and clean all the gaskets, replacing the gaskets, and most likely the o-rings too...
KAM
#17
Supreme Member
You won't remove the clips to pull the injectors out of the intake. You want them in the fuel rail still. You just need to remove the plenum and loosen the runners, remove some bolts and pull the injectors out. You might want to replace the o-rings, but the gaskets will be fine unless they're ancient and break, in which case they should be replaced anyhow.
You can clamp off the return line beside the drivers side accessories where it's rubber.
You can clamp off the return line beside the drivers side accessories where it's rubber.
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