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  1. #1
    14 PSI Boost 1986SVOTURBO's Avatar
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    SVO's: 1986 SVO

    SVO jumpy at very low speed.

    Is anyone else’s SVO jumpy going about 5 mph in first? When I drove an SVO, it was kind of like bouncing around. I then remembered My SVO was jumpy at low speeds.

  2. #2
    Administrator SVOeric's Avatar
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    SVO's: 86-1C & 86-1E
    not real sure what you mean by jumpy, any manual transmission car (especially 4-cylinders) will get bouncy if you aren't smooth with the gas pedal.
    Eric C
    SVOCA Webmaster

  3. #3
    Pimpin Pumpkin Carver Laredo's Avatar
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    SVO's: 86 2R
    Quote Originally Posted by 1986SVOTURBO View Post
    Is anyone else’s SVO jumpy going about 5 mph in first? When I drove an SVO, it was kind of like bouncing around. I then remembered My SVO was jumpy at low speeds.
    Can you provide more clarification on your "jumpy" term?
    Up/down, forward/back, side -to-side, accelerating, constant speed, etc...?
    "If there's no plan, what can go wrong...?"

  4. #4
    OVER-BOOST!! svono50's Avatar
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    SVO's: 86 1C
    If your 'jumpy' is the car feels like it is getting bumped from behind (i.e.- trailer hitching), then some potential causes are a worn TPS or a sticky IAB valve or a bad base idle setting. Last summer I went through the full base idle setup/adjustment and also dialed back my TPS from 0.95V down to 0.70V and it certainly helped out a lot with low speed cruise stability below 30 mph. There are other things that can also cause this, but this would be the main area to go over first to see if any improvement can be found.
    Ted
    86 SVO Mustang
    17 Cooper S Clubman ALL4

  5. #5
    14 PSI Boost 1986SVOTURBO's Avatar
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    I should have used the work bucks instead. It is between 0-5MPH.

  6. #6
    OVER-BOOST!! gbeaird's Avatar
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    Yeah, that's not normal. As Ted says, look first at the TPS voltage as you slowly open the throttle. It should be smooth. I'll add to ask how old your gas is? Modern gas with alcohol in it is terrible on a good day. Let it sit in a gas tank for a few months, it could have so much water in it, the car won't even run. And if it does start and run, it won't under any load.
    Last edited by gbeaird; 04-18-2021 at 12:59 PM.
    Gene Beaird,
    86 2R SVO, G Stock,
    Pearland, Texas

  7. #7
    14 PSI Boost 1986SVOTURBO's Avatar
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    Quote Originally Posted by gbeaird View Post
    Yeah, that's not normal. As Ted says, look first at the TPS voltage as you slowly open the throttle. It should be smooth. I'll add to ask how old your gas is? Modern gas with alcohol in it is terrible on a good day. Let it sit in a gas tank for a few months, it could have so much water in it, the car won't even run.
    Thank you for the heads up.

  8. #8
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    SVO's: 1986 1D 54k miles

    What?

    Quote Originally Posted by 1986SVOTURBO View Post
    Let it sit in a gas tank for a few months, it could have so much water in it, the car won't even run.
    When did gasoline/ethanol start making water?

  9. #9
    OVER-BOOST!! gbeaird's Avatar
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    Quote Originally Posted by CloudNine View Post
    When did gasoline/ethanol start making water?
    Ethanol is hygroscopic, and can pull water out of the air as the tank 'breathes' with temperature changes. In no time, you have a lot of water in the fuel.
    Gene Beaird,
    86 2R SVO, G Stock,
    Pearland, Texas

  10. #10
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    SVO's: 1986 1D 54k miles

    Ethanol Fuel

    Quote Originally Posted by gbeaird View Post
    Ethanol is hygroscopic, and can pull water out of the air as the tank 'breathes' with temperature changes. In no time, you have a lot of water in the fuel.
    Your statement is partially correct, sir that ethanol is hygroscopic, but the remainder is not (unless, possibly, if the tank is left uncapped for a long time in humid conditions). Gas tanks run dryer, not wetter with ethanol. I am old enough to remember non-ethanol gasoline. In those days, I would constantly encounter frozen gas lines in winter. Remember "HEET" (methanol)? When E10 became common, the gas line freeze-up problem disappeared and consequently, HEET is mostly obsolete.

    Here's an explanation that I found.

    Water absorption: No doubt that ethanol emulsifies and holds water. Yay!! That’s a good thing! In fact, “holding” / suspending /emulsifying water is an ethanol ASSET — not detriment — as gas tanks actually run dryer after the transition from E0 to E10. Specifically with regard to moisture, a gallon of ethanol suspends FOUR (4) TEASPOONS of water per gallon of fuel before phase separation. On the other hand, gasoline suspends only POINT ONE FIVE (.15) TEASPOON (that’s LESS than ONE teaspoon) of water per gallon before phase separation. So PHASE SEPARATION WILL OCCUR 26 TIMES MORE RAPIDLY WITH GASOLINE THAN WITH ETHANOL! This has been demonstrated hundreds of times (including one demonstration I recently saw by Dr. Andrew Randolph, technical director of Earnhardt-Childress Racing), clearly substantiating that gasoline does NOT effectively hold (suspend) water. So with straight gasoline, whatever water is in any tank or atmosphere “phase separates” and falls to the bottom of the tank. In contrast in ethanol-blended fuel, the ethanol will suspend that water during the driving of the vehicle; then, harmlessly carry it through the system to be vaporized by the engine without affecting the engine in the least. The suspended water, vaporized by the engine, produces NO harmful emissions. And one more point: at 70 degrees Fahrenheit and 70 percent relative humidity, it takes more than two months for even gasoline to absorb water. Since ethanol has 26 times the suspension capability of gasoline, it would take literally months and months before any phase separation could possibly take place. I can state categorically that I own a Classic 1980 Limited Edition Weissach Porsche 911 and have driven it three times in the past three years … to buy fresh gas. I start this vehicle (about every three months) and let it run for no less than ˝ hour to circulate the E10 gas.

    Can’t We Just Get Rid of Ethanol Ignorance? | Renewable Fuels Association (ethanolrfa.org)

  11. #11
    OVER-BOOST!! gbeaird's Avatar
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    Gas line freezing may have disappeared, but dissolved water in the gas makes for a corrosive mix that will rust tanks and parts more-rapidly. It's especially bad on aluminum, which all carburetors are made of. It's nasty stuff to let sit around, hence the vehicles in our collection all run ethanol-free fuel.
    Gene Beaird,
    86 2R SVO, G Stock,
    Pearland, Texas

  12. #12
    6 PSI Boost
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    Quote Originally Posted by gbeaird View Post
    Gas line freezing may have disappeared, but dissolved water in the gas makes for a corrosive mix that will rust tanks and parts more-rapidly. It's especially bad on aluminum, which all carburetors are made of. It's nasty stuff to let sit around, hence the vehicles in our collection all run ethanol-free fuel.
    Again, gas tanks run dryer, not wetter, with ethanol gasoline. The water molecule attaches to the ethanol molecule and takes it out of the corrosion game. It's as if the water is not there anymore. All one has to do is ingest enough alcohol to experience the dehydration that follows.

    Of course, that's just to illustrate the point. People are not cars and vice versa. But considering all the aluminum and other corrode-able metals in use in modern cars, there would be massive havoc if that was correct. There just is not. I have used ethanol gasoline in classic cars throughout the years and never had any corrosion due to ethanol in any fuel system. In fact, all of my cars ran better because of the octane added by ethanol. Personally, I believe that the octane rating of ethanol gasoline is often HIGHER than stated on the pump. For marketing purposes, the oil companies want to give you a reason to buy more expensive premium fuel, so they de-rate the octane of regular fuel.

    Of course, one should regularly cycle the gasoline through the fuel system of any car that sits for long periods of time. The gasoline will go stale and gum up the system. That is what you are experiencing.

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