Bad Fuel Injector?

Posted by habitatguy187, Oct 22, 2008
Tuning & Engine Management - 4G63 EPROMS, ECU, MAF, knock, EGT, wideband, datalogging, fuel trims, etc. Read this Forum's Strict Guidelines.

  1. habitatguy187

    habitatguy187 Proven Member

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    Ok, I've been trying to track down this problem for awhile now, and to no avail. What happens is if I drive my car for awhile, shut it down, then start it up soon after, it idles real bad and misses out while cruising under 15mph. Now the annoying problem is that when I boost into the 5k rpm range I get such a bad miss that it almost feels like fuel cut. (def. not as violent as fuel cut though)

    I've changed plugs and wires, done BLT after BLT with soapy water and fixed all problems, fixed all vacuum leaks. Boost is set at 13psi. So could this be a bad fuel injector? Is there any way to test if a fuel injector is bad? Or maybe the ppl who owned the car before me put in smaller injectors???

    Also when I start my car warm the vac pressure is real sporatic (sometimes vac is -18 at normal idle, but most of the time at or around -16 at normal idle, sometimes as low as -13), and it almost feels like the car is running too rich, but after I drive around a bit, it's fine.

    Please help. I'm getting pretty fed-up with this crap. And please don't tell me to do a BLT, cause I've done like 50 in the last 2 weeks. Thanks
     
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  2. spectr019

    spectr019 Proven Member

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    well the hacked mass is kinda a ghetto trick that can sometimes easily screw up the mas reading...also, I've NEVER seen somebody do a mod "removing all vacuum lines"...If that's as simple as it sounds, then there would be your IN HG problem, as well as driving issues.

    Ben :talon:
     
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  3. habitatguy187

    habitatguy187 Proven Member

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    I know it's not the mass cause I tried out my friend's in my car and same thing happened. As for "all vacuum lines" I should've said, "all vacuum lines according to taboo speed shop diagram" (except for fpr vacuum line) Anyway, how can I tell if an injector is bad?
     
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  4. spectr019

    spectr019 Proven Member

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    to see specifically if an injector is bad...I personally haven't heard of any methods to do that. If you are pretty suspicious of an injector, I would first ask how old they are? If they are pretty old, or if they have been sitting unused for a long time, throw some fuel injector cleaner through them and see if that helps at all.
    If you think that the car is running rich, I would think it would run lean if an injector isn't working up to par, unless the other injectors are controlled by the ecu to inject way more than normal (which consequently would put them attempting to be over 100% idc).
    My very first thoughts before I finished reading your initial post was to check the wires, your symptoms were very familiar to me, and I found out that it was the wires.
    I guess if you think it's an injector, just put new injectors in. Or if you have your old injectors, re-set whatever fuel controller your using, and put in the old 450s and see how it goes. Good luck whichever way you go though.

    Ben
     
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  5. habitatguy187

    habitatguy187 Proven Member

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    I've put in 3 bottles of fuel injector cleaner in the car in the last 2 months, and I'm still on stock fuel settings. I was wondering if you could tell if an injector was leaning out by the way the spark plug nearest it looked? I don't know a whole lot about spark plugs though, so any word of advice will help.
     
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  6. PIMking

    PIMking Proven Member

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    seafoam it...
     
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  7. thebird_19

    thebird_19 Proven Member

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    What shape are your coil packs in?
     
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  8. redyute1

    redyute1 Proven Member

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    You can use a digital multimeter to test the resistance of the injector,set the meter to ohms disconnect the injector and test them they sould be within range of each other.That test lets you know if you have a bad injector coil.
     
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  9. habitatguy187

    habitatguy187 Proven Member

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    Just stick the multimeter prong into the injector clip thing? And if I have a bad coil do I need new injectors also? Thanks
     
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  10. byebyev8

    byebyev8 Proven Member

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    Try some injector cleaner. It really works my old car would do almost the same thing but alot worse(If I started the car warm it would idle and run terrible almost like it was on 3 cylinders). At first i thought it was a hot start problem then my car threw the bad injector CEL and before i got new injectors i tried the cleaner and it never happened again.
     
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  11. spectr019

    spectr019 Proven Member

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    That's not a bad idea you were saying about the plugs. If one injector is not putting in enough fuel, then the plug will have a semblance different from the others. You said you changed the plugs already, if you still have them, take a look at those bad boys. If one is different, it's not necessarily an injector, but something to do with a certain cylinder, you'll just have to figure out which one and go from there.

    Ben :talon:
     
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  12. habitatguy187

    habitatguy187 Proven Member

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    So today I changed my fuel filter, and while I had the battery out I noticed my charcoal can, I traced a vac. line back to the intake, but I saw some other lines missing on the charcoal can, so this may be my problem (I thought I had checked all the vac lines), I'm gonna cap the intake nipple tonight and keep you guys posted.

    I guess it makes sense cause this one wouldn't show up in a BLT because it's before the turbo inlet.
     
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  13. snowborder714

    snowborder714 Moderator

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  14. habitatguy187

    habitatguy187 Proven Member

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    No that wasn't it, see the guy before me ripped out a lot of hoses, and I've still got a vac. leak somewhere, but I was thinking, if the charcoal canister isn't hooked up but the line from the intake is hooked up to it, would it lose enough air to cause a mild fuel cut?

    On second thought, this isn't fuel cut so it must be something to do with the fuel system.
     
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  15. habitatguy187

    habitatguy187 Proven Member

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    Sorry it's been so long, but anyway, I checked my plugs all turned out ok, re-wired my fuel pump and still having a problem. I was thinking that maybe I have the automatic injectors in my car. Is there a way to tell the difference between the 450s and the autos?
     
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  16. steve

    steve DSM Wiseman

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    http://www.dsmtuners.com/forums/bolt-tech/221081-injector-identification.html
    http://www.dsmtuners.com/forums/newbie-forum/245844-tan-injectors.html
    http://www.dsmtuners.com/forums/newbie-forum/264867-injector-color-question.html
     
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