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Idles fine, falls on its face when you open the throttle.

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  • Idles fine, falls on its face when you open the throttle.

    Still need to pick up leads for my DMM to test the TPS. I did start the car with the tps unhooked and it did exactly the same thing as it did with it plugged in. New plugs (NGK V Power .044 gap), Autolite Wires, new cap and rotor, new coil, new icm. New fuel pump and filter. Only thing I haven't messed with seems to be the PCM/TPS/VAF/O2 thus far. Any ideas what could cause this?

    And when I say falls on its face, it sounds like it's loading up with fuel (and smells that way too!) But it idles perfect.

    I have a Haynes, just not sure what components to start with
    93 Ford Festiva L 5 speed: In process of fixing PO's negligence

  • #2
    The TPS on these doesn't really do much. It signals Idle and WOT...that's about it. I would look at the VAF meter next.
    Brian

    93L - 5SP, FMS springs, 323 alloys, 1st gen B6, ported head & intake, FMS cam, ported exhaust manifold w/2-1/4" head pipe.
    04 Mustang GT, 5SP, CAI, TFS plenum, 70mm TB, catted X, Pypes 304SS cat-back, Hurst Billet+ shifter, SCT/Bama tuned....4.10's & cams coming soon
    62 Galaxie 2D sedan project- 428, 3x2V, 4SP, 3.89TLOC

    1 wife, 2 kids, 9 dogs, 4 cats......
    Not enough time or money for any of them

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    • #3
      Sounds like a stuck VAF.

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      • #4
        Well crap. Is that a visual inspection thing? Haven't even seen inside it (slipped airbox open to put in the k&n a while ago but that's it)
        93 Ford Festiva L 5 speed: In process of fixing PO's negligence

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        • #5
          VAF and also check your intake hose (from the VAF to the Throttle body). Could have an air leak which would mean your getting in unmeasured air flow which is throwing off your Air to Fuel ratio

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          • #6
            As said above, take a good look for air leaks, ensure the VAF is opening properly, and give the throttle body a good cleaning just in case it is sticking.
            1988 Chevy Sprint Turbo 997cc

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            • #7
              Throttle body is functioning fine. Snaps open and shut with ease, doesn't hang up at all.

              Sprayed carb clean all over any gasket/mating surface between the VAF and the cylinder head, no vac leaks.

              If the VAF was stuck, wouldn't it make idle super rich and it eventually die? Wish I still had my Innovate LC1 so I could see what's going on. Lol.
              93 Ford Festiva L 5 speed: In process of fixing PO's negligence

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              • #8
                I wonder if a bad ignition control modual or sensor in the dizzy would cause these symptoms? Maybe it's not an A/F ratio issue....if the spark is crapping out, then the mixture isn't burning completely and what you are smelling is unburnt fuel, as opposed to excess fuel. Just trying to think outside of the box.
                Brian

                93L - 5SP, FMS springs, 323 alloys, 1st gen B6, ported head & intake, FMS cam, ported exhaust manifold w/2-1/4" head pipe.
                04 Mustang GT, 5SP, CAI, TFS plenum, 70mm TB, catted X, Pypes 304SS cat-back, Hurst Billet+ shifter, SCT/Bama tuned....4.10's & cams coming soon
                62 Galaxie 2D sedan project- 428, 3x2V, 4SP, 3.89TLOC

                1 wife, 2 kids, 9 dogs, 4 cats......
                Not enough time or money for any of them

                Comment


                • #9
                  Has a new icm, the pickup coil in the dizzy is a possibility although I figured it would cause an issue constantly.
                  93 Ford Festiva L 5 speed: In process of fixing PO's negligence

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                  • #10
                    I would look at your distributor rotor to see if there is any trace of high voltage going to ground through the dist shaft (black burn marks). $4 part. Runs fine no load (low spark voltage demand) loaded (high demand) spark takes the short cut.
                    Last edited by XFSE71; 03-08-2013, 10:53 PM.
                    '88 LX (VIN#30) one of the first Built 12/86
                    '88 L (VIN#55753) Built 12/87
                    '93 GL one of the last Built 5/19/93

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                    • #11
                      my favorite is a leaking distributor shaft seal and oil puddling in the cap
                      '90 L-Plus 420,000 miles , rusting hard and going to the chopping block


                      '97 Honda CR-V , 91,000 miles and just starting its journey

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                      • #12
                        You know, I end up with a little bit of something in the cap after a few thousand miles... and I replaced the rotor recently but hell, I'll warranty swap it and see if that changes anything!
                        93 Ford Festiva L 5 speed: In process of fixing PO's negligence

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                        • #13
                          You might be better off looking to see if you can find out which is actually the causal part rather than buying a new one.
                          how hot is your coil? Yellow spark is weak, blue spark is hot.
                          There are a couple of things that would cause smooth idle and no revs ... air flow in and out ... How the air filter and exhaust(plugged cat ... here we go). Can you put a vacuum guage on the manifold? How dooes it sound at the tailpipe ... is it breathing?
                          '88 LX (VIN#30) one of the first Built 12/86
                          '88 L (VIN#55753) Built 12/87
                          '93 GL one of the last Built 5/19/93

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                          • #14
                            K&n filter, no cat. The car isn't idling smoothly anymore. Replaced c&r, no change.

                            Vaf moves freely too. How should I check the ignition coil exactly?

                            I could always swap that too lol
                            Last edited by standard235; 03-09-2013, 12:05 PM.
                            93 Ford Festiva L 5 speed: In process of fixing PO's negligence

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                            • #15
                              quick check is to pull a plug wire engine running and look at the color of the spark. proper way is put it on a scope and look for 40KVor better.
                              maybe you should resubmit you symptoms andwhat has been done to give us a better feel for what you are up against. You know there only a few things that can go wrong and each problem has a unique signature. Think CSI.
                              '88 LX (VIN#30) one of the first Built 12/86
                              '88 L (VIN#55753) Built 12/87
                              '93 GL one of the last Built 5/19/93

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