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  • Need Help Pinpointing Problem

    Ok, I posted this on another forum, so I'm going to meld it all together. I was wondering if I could get some advice or opinions on what my problem might be.

    ...

    Well, I really don't know what it is, but I'm hoping you guys could give me some advice and direction. Recently the engine has been having some trouble starting, although the frequency varies. Sometimes it will also idle very rough and surge while in park. I also noticed a small ticking sound coming from somewhere. It also shifts hard out of park into drive from time to time, but I think that may be because its sits for awhile. Although I drove it around for the past two days and it did it.

    Otherwise it seems to run fine during hard acceleration and just normal around town cruising. Any ideas?

    ...

    No SES lights at all, the only time its comes on is when I get onto the highway. I checked that out and its just because I have a different filter on the car (so its a MAF thing).

    As for RPMs, I don't have a tach, so I don't have a way of checking atm.

    ...

    I'm not entirely sure, but my mechanic checked it when it was on last (its comes off and on, usually when I jump on the highway) and said it was the air filter causing it. For the record, my mechanic is the only one I trust with my car, so I believe him.

    I was just thinking back though. When I changed the rad hoses recently and took it out for a drive, the car stumbled and wouldn't accelerate, which my dad said never happened last time. It did it twice, once at around 60KPH, and once at about 80 as I was getting on the highway. It has ran fine since though.

    Would the fuel filter have anything to do with that?

    ...

    I also can hear a constant whirring sounds as the car drives that has started to become steady the past little while.

    ...

    The first part is my original post, the second two are answer to questions as well as some clarification and further explanation. Hopefully that will save some time.

    Dual Outlet Exhaust with Resonator Delete, Front STB, Rear STB, GMPP Trailing Arms

  • #2
    just a stab in the dark... But, sounds like a fuel problem to me.

    The loud whirring sounds like it could be the fuel pump on it's way..

    Or, the fuel filter could be getting iffy and that is causing too much back pressure for the pump - making the whirring sound...

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    • #3
      I'll get that checked this weekend along with the MAF, does anyone have any other ideas?

      Dual Outlet Exhaust with Resonator Delete, Front STB, Rear STB, GMPP Trailing Arms

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      • #4
        K&N and other oil type filters can contaminate MAF's with oil. If that happened then that would be your problem.
        sigpic New 2010 project (click image)
        1994 3100 BERETTA. 200,000+ miles
        16.0 1/4 mile when stock. Now ???
        Original L82 Longblock
        with LA1, LX9, LX5 parts
        Manifold-back 2.5" SS Mandrel Exhaust. Hardware is SS too.

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        • #5
          How many miles are on your vehicle and are you talking about or car listed in your profile?

          Having a contaminated MAF can cause several things to drift values however not enough to throw a code on all sensors effected by a MAF. The MAF has the most effect on stiotch. If you have a high impedance multimeter then you may want to test the o2 sensor and directly see if the engine is running lean or rich.

          Usually a good way of knowing if a fuel filter is pluged is with a pressure gauge with a primer valve to test flow only when the key in turned to on engine not running, using the power on cycle pump test. The reason you don't want to engine running is because the pressure then is regulated and it is difficult gauge flow, however testing the fuel pressure through RPM will determine the regulators capacity range. Some vehicles have a return comp fitting and am not sure if yours does.

          Through the primer valve use a clear hose to see if the fuel is discolored, if it is this usually this means the filter is bypassing.
          Last edited by Juglenaut; 10-25-2007, 09:44 AM.
          I am back

          Mechanical/Service Technican

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          • #6
            Originally posted by Juglenaut View Post
            How many miles are on your vehicle and are you talking about or car listed in your profile?

            Having a contaminated MAF can cause several things to drift values however not enough to throw a code on all sensors effected by a MAF. The MAF has the most effect on stiotch. If you have a high impedance multimeter then you may want to test the o2 sensor and directly see if the engine is running lean or rich.

            Usually a good way of knowing if a fuel filter is pluged is with a pressure gauge with a primer valve to test flow only when the key in turned to on engine not running, using the power on cycle pump test. The reason you don't want to engine running is because the pressure then is regulated and it is difficult gauge flow, however testing the fuel pressure through RPM will determine the regulators capacity range. Some vehicles have a return comp fitting and am not sure if yours does.

            Through the primer valve use a clear hose to see if the fuel is discolored, if it is this usually this means the filter is bypassing.
            I'm talking about the car in my sig and my profile yes. I have about 260000 KMS on it now (161500 miles roughly).

            Well, I am heading back up to my hometown this weekend, so I'm going to get my mechanic to have a look at it and see if is any of the suggested items.

            Thanks for the help and suggestions so far.

            Dual Outlet Exhaust with Resonator Delete, Front STB, Rear STB, GMPP Trailing Arms

            Comment


            • #7
              UPDATE:

              I finally filled up with gas today, my mileage went down drastically since the last time I filled up. I did have a mix of city and highway last fill, but generally I would get around 23 or 24 MPG. Now I am getting 16 MPG. I'm definitely going to look into the fuel filter, since I can't even remember the last time it was changed, and neither can the previous owner.

              Dual Outlet Exhaust with Resonator Delete, Front STB, Rear STB, GMPP Trailing Arms

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              • #8
                Anything yet???

                I am very curious as to what is causing the huge drop in MPG...

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                • #9
                  haha uh oh. i only get 16-19mpg city on the 3.1sfi with a 15k mile old fuel filter new air filter, new MAF, new pcv. new intake gaskets... shits fairly fixed up. no ideas why its running so inefficient. so when you find out, post up ASAP

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