Bouncing tach - no performance change

Discussion in '94-95 5.0 - Specific' started by Saint, Dec 17, 2013.

  1. Saint

    Saint Active Member

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    Car is 95 5.0 - 306 crate

    The tachometer started bouncing today...There is NO performance change although the tach is bouncing. Very Strange. The rmp gauge will bounce at idle and while I am driving. But the actual sound of the engine does NOT change at all when it bounces. Car sounds perfectly fine which is leading me to believe this is electrical. Any idea's?

    There are NO exhaust leaks on the car just would like to clear that up.

    The ignition system....the entire ignition system is about 7months old including the distributor.

    The MAF was cleaned about 6 months ago during regular maintenance.

    I'd just like to reiterate the car is NOT stumbling when the tach bounces...there is NO sound change what-so-ever so I'm baffled on this one.
     
  2. Win

    Win Legend

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    Your going to have to pull your gauge cluster. While it's out change the worm gear and odo gear. Very possibly a bad contact... If that doesn't work take a peak into this to trace the ground.

    [​IMG]
     
  3. Saint

    Saint Active Member

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    Would that have caused my car to stop running?

    Was on my way to get a new coil before the parts store close and it went Kaput....just shut off...My ignition coil feels loose and rocks around in the square housing...also the prong that my dizzy wire connects to on the coil spins around and looks messed up. I tested it and it's getting 12 volts but everything on it is loose. Car cranks but doesn't start. I dropped in my brand new backup dizzy before the tow truck came...it's not the dizzy.
     
  4. Win

    Win Legend

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    Sounds like you have a bad ground somewhere that has just degraded over time.
     
  5. Saint

    Saint Active Member

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    Man...going to suck finding it...I reworked all major grounds last year. I don't know where any other grounds are at :-/ ....fuse box ground engine, engine to frame ground, PCM ground, The ground on the passenger side by the console and battery to block ground.. even the grounds in the trunk. If I can't figure it out tomorrow I'm just going to take it to ford and sell it after they fix it. I swear I am sick of working on cars. I've been doing this since I was 13. I'm done. Going to get something 09 and up and jump back in the game later in life.

    I may keep it if the ignition coil fixes it...pretty sure it's bad wobbling around like that...I'll keep this updated... Should have the coil on after work around 4 or 5 tomorrow. That coil is actually about 2 years old now that I think about it.

    No...selling it even if that fixes it. These cars are bad luck.
     
  6. Win

    Win Legend

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    Well hopefully it fixes it if not post back up and we'll figure it out. Just get a 11 5.0... after my girl has had one for almost 9 months i love it every time i drive it. If i wasnt having to pay for a wedding and all i would be in one in a heartbeat!
     
  7. Saint

    Saint Active Member

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    Thanks man!

    I'm thinking that the plugs are bad and caused the coil to push itself a lot harder. It's been exactly 10 months since I did plugs and wires. So it's probably that time. I've always done wires and plug every 12 months.

    Going to do plugs, wires and coil tomorrow. The car just needs too much maintenance. Between work and freelancing. I just don't have time for it anymore. I can't have stuff just fail mid week like this. Maybe I should have been doing wires and plug every 6 months.

    Either way...it has to go. :(
     
  8. the5.ohh

    the5.ohh Legend

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    my brothers 91 fox does the same exact thing. tach needle bounces all the time, now the speedo started too. i told him we gotta pull the cluster out and figure it out lol
     
  9. Orange 94

    Orange 94 Moderator Staff SN95 Supporter

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    Man Saint, you have bad luck with sn95s :(
     
  10. Saint

    Saint Active Member

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    I know right. I'm tired of it. In all actuality I'm into too many kinds of cars to keep fooling with ONE. I'm in the market for a 2010 Audi A4 sport package or a Ford Raptor. I'll probably put the GT in storage until I can start a 418 stroker build.
     
  11. Caboose302

    Caboose302 Well-Known Member

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    Mine was doing this. Found out the guy who owned the car before me used speaker wires for the install.
     
  12. Saint

    Saint Active Member

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    Speaker wires for what install....for battery cables or something.
     
  13. Caboose302

    Caboose302 Well-Known Member

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    The tach install. They used speaker wire for the ground and signal wire.
     
  14. Saint

    Saint Active Member

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    oh...my tach is stock...pretty sure the coil is fryed it wiggles a bunch in the housing like it shrank or something. New ones don't do that. About to throw on plugs, coil and wires in a few. Gotta another crap BWD coil until my screamin demon coil gets here and my 9mm wires.
     
  15. Saint

    Saint Active Member

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    Update:

    Replaced coil, plugs and wires.....still cranking but not starting.

    I checked for spark at the #1 plug....No spark...

    I pulled the coil wire off the dizzy and connected a spark plug to it.....no spark....Replaced EEC fuse although it looked fine....no spark

    Old plugs were covered in fuel from trying to crank it so it's getting fuel.

    I'm baffled...

    Wondering if the EEC Relay has failed inside the CCRM...

    Why would a brand new coil not produce spark? Maybe a bad fuse link somewhere? CCRM?

    I'm stumped and I know if I take it to Ford I'll get raped.
     
  16. Saint

    Saint Active Member

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    Swapping the CCRM from my v6 into the GT tomorrow... found out that it will work just fine. I've read at least 100 post on other forums, someone has been riding around with a CCRM from a Sable in their 95 for 2 years with no issues lol.

    It is the last thing I can think of that would cause my coil not to throw spark...last night when my dad was cranking the car I saw spark shoot from the coil through the spark plug wire boot...that was probably the CCRM's last stand before the relay inside of it gave.
     
  17. Caboose302

    Caboose302 Well-Known Member

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    Hope that fixes it! Sorry, I was reading your post all wrong about the tach thing, lol
     
  18. 95opal

    95opal Well-Known Member

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    The ccrm isn't as prone to failure as the tfi or pip.
    This is the most proficient way to track down a no start problem

    Note: 94-95 specific changes are in red

    1.) Remove push on connector (small red/blue wire) from starter solenoid and turn ignition switch to the Run position. Place car in neutral or Park and set the parking brake. Remove the coil wire from distributor & and hold it 3/8” away from the engine block. Jumper the screw to the big bolt on the starter solenoid that has the battery wire connected to it. You should get a nice fat blue spark.
    Most of the items are electrical in nature, so a test light, or even better, a voltmeter, is helpful to be sure they have power to them.

    No spark, possible failed items in order of their probability:
    A.) MSD or Crane ignition box if so equipped
    B.) PIP sensor in distributor. The PIP sensor supplies the timing pulse to trigger the TFI and injectors. A failing PIP sensor will sometimes let the engine start if the SPOUT is removed. See paragraph 5A – Using a noid light will tell if the PIP is working by flashing when the engine is cranking.
    C.) TFI module: use a test light to check the TFI module. Place one lead of the test light on the red/green wire on the ignition coil connector and the other lead on the dark green/yellow wire on the ignition coil connector. If the TFI is working properly, the test light will flash when the engine is cranked using the ignition switch.
    D.) Coil
    E.) No EEC or computer power - EEC or computer relay failure
    86-93 models only: EEC relay next to computer - look for 12 volts at the fuel injector red wires.
    94-95 models only: EEC or PCM power relay in the constant control relay module. Look for 12 volts at the fuel injector red wires.
    Both 86-93 and 94-95 models: No 12 volts with the ignition switch in the run position on the fuel injector red wires. The relay has failed or there is no power coming from the ignition switch. Make sure that there is 12 volts on the red/green wire on the coil before replacing the relay.
    F.) No EEC or computer power - fuse or fuse link failure
    86-93 models only: Fuse links in wiring harness - look for 12 volts at the fuel injector red wires. All the fuse links live in a bundle up near the starter solenoid. Look for a 20 gauge blue fuse link connected to 2 black/orange 14 gauge wires.
    94-95 models only: 20 amp EEC fuse in the engine compartment fuse box. Look for 12 volts at the fuel injector red wires.
    G.) Ignition switch - look for 12 volts at the ignition coil red/lt green wire. No 12 volts, blown fuse link or faulty ignition switch. Remove the plastic from around the ignition switch and look for 12 volts on the red/green wire on the ignition switch with it in the Run position. No 12 volts and the ignition switch is faulty. If 12 volts is present in the Run position at the ignition switch but not at the coil, then the fuse or fuse link is blown.
    Note: fuses or fuse links blow for a reason. Don’t replace either a fuse or fuse link with one with a larger rating than stock. Doing so invites an electrical fire.
    Ignition fuse links may be replaced with an inline fuse holder and 5 amp fuse for troubleshooting purposes.
    94-95 models only: Check inside fuse panel for fuse #18 blown – 20 amp fuse
    H.) Missing or loose computer power ground. The computer has its own dedicated power ground that comes off the ground pigtail on the battery ground wire. Due to it's proximity to the battery, it may become corroded by acid fumes from the battery.
    In 91-95 model cars it is a black cylinder about 2 1/2" long by 1" diameter with a black/white wire.
    You'll find it up next to the starter solenoid where the wire goes into the wiring harness
    I.) Computer.
    J.) Bad or missing secondary power ground. It is located between the back of the intake manifold and the driver's side firewall. It supplies ground for the alternator, A/C compressor clutch and other electrical accessories such as the gauges.
    K.) Engine fires briefly, but dies immediately when the key is released to the Run position. Crank the engine & when it fires off, pull the small push on connector (red wire) off the starter relay (Looks like it is stuck on a screw). Hold the switch in the crank position: if it continues to run there is a problem with either the ignition switch or TFI module. Check for 12 volts at the red/green wire on the coil with the switch in the Run position. Good 12 volts, then replace the TFI. No 12 volts, replace

    2.) Spark at coil wire, pull #1 plug wire off at the spark plug and check to see spark. No spark, possible failed items in order of their probability: [/b]
    A.) Moisture inside distributor – remove cap, dry off & spray with WD40
    B.) Distributor cap
    C.) Rotor
    D.) Spark Plug wires
    E.) Coil weak or intermittent - you should see 3/8" fat blue spark with a good coil

    3.) Spark at spark plug, but no start.
    Next, get a can of starting fluid (ether) from your local auto parts store: costs a $1.30 or so. Then pull the air duct off at the throttle body elbow, open the throttle, and spray the ether in it. Reconnect the air duct and try to start the car. Do not try to start the car without reconnecting the air duct.

    Two reasons:
    1.) If it backfires, the chance for a serious fire is increased.
    2.) On Mass Air cars, the computer needs to measure the MAF flow once the engine starts.
    If it starts then, you have a fuel management issue. Continue the checklist with emphasis of fuel related items that follow. If it doesn’t, then it is a computer or timing issue: see Step 4.

    Clue – listen for the fuel pump to prime when you first turn the ignition switch on. It should run for 5-20 seconds and shut off. To trick the fuel pump into running, find the EEC test connector and jump the connector in the Upper RH corner to ground. The EEC connector is near the wiper motor and LH hood hinge.

    If the relay & inertia switch are OK, you will have power to the pump. Check fuel pressure – remove the cap from the Schrader valve behind the alternator and depress the core. Fuel should squirt out, catch it in a rag. Beware of fire hazard when you do this. In a pinch, you can use a tire pressure gauge to measure the fuel pressure. It may not be completely accurate, but you will have some clue as to how much pressure you have. If you have any doubts about having sufficient fuel flow/pressure, rent a fuel pressure test gauge from the auto parts store. That will tell you for sure if you have adequate fuel pressure.


    4.) No fuel pressure, possible failed items in order of their probability:
    A.) Tripped inertia switch – Coupe & hatch cars hide it under the plastic trim covering the driver's side taillight. Use the voltmeter or test light to make sure you have power to both sides of the switch
    B.) Fuel pump power relay – located under the driver’s seat in most stangs built before 92. On 92 and later model cars it is located below the Mass Air Flow meter. Look for 12 volts at the Pink/Black wire on the fuel pump relay.
    C.) Clogged fuel filter
    D.) Failed fuel pump
    E.) 86-90 models only: Blown fuse link in wiring harness. Look for 12 volts at the Orange/Lt Blue wire on the fuel pump relay.
    91-93 models only Blown fuse link in wiring harness. Look for 12 volts at the Pink/Black wire on the fuel pump relay.
    The fuse links for all model years 86-93 live in the wiring harness near the starter solenoid.
    94-95 models only: 20 amp fuel pump fuse in the engine compartment fuse box. Look for 12 volts at the Dark green/yellow wire on the constant control relay module.
    F.) Engine seem to load up on fuel and may have black smoke at the tailpipe. Fuel pressure regulator failed. Remove the vacuum line from the regulator and inspect for fuel escaping while the pump is running. If fuel is coming out the vacuum port, the regulator has failed. Check the regulator vacuum line for fuel too. Disconnect it from the engine and blow air though it. If you find gas, the regulator has failed.

    5.) Fuel pressure OK, the injectors are not firing.
    A.) The PIP sensor in the distributor tells the computer when to fire the injectors. A failing PIP sensor will sometimes let the engine start if the SPOUT is removed.
    A noid light available from any auto parts store, is one way to test the injector circuit to see if the injectors are firing. The noid light plugs into the fuel injector harness in place of any easily accessible injector. Plug it in and try to start the engine: it will flash if the injector is firing.
    B.) I like to use an old injector with compressed air applied to the injector where the fuel rail would normally connect. I hook the whole thing up, apply compressed air to the injector and stick it in a paper cup of soapy water. When the engine cranks with the ignition switch on, if the injector fires, it makes bubbles. Cheap if you have the stuff laying around, and works good too.
    D.) Pull an injector wire connector off and look for 12 volts on the red wire when the ignition switch is on.
    The injector power pin is the VPWR pin in the black 10 pin connector.
    F.) No power and the 10 pin connections are good: look for broken wiring between the orange/black wire on the EEC relay and the red wire for the 10 pin connectors.
    G.) TPS voltage exceeds 3.7 volts with the throttle closed. This will shut off the injectors, since the computer uses this strategy to clear a flooded engine. Use a DVM, a pair of safety pins, and probe the black/white and green wires to measure the TPS voltage.
    On a 94-95 Mustang, probe the black/white and grey/white wires to measure the TPS voltage.
    It should be .5-.1.0 volts with the key on, engine not running. Note that if the black/white wire (signal ground) has a bad connection, you will get some strange readings. Make a second measurement using the battery post as the ground to eliminate any ground problems. If the readings are different by more than 5%, you may have a high resistance condition in the black/white signal ground circuit.
    6.) Spark & fuel pressure OK.
    A.) Failed IAB or improperly set base idle (no airflow to start engine). Press the throttle ¼ way down and try to start the car. See the "Surging Idle Checklist for help with all your idle/stall problems.
    B.) Failed computer (not very likely)
    C.) Engine ignition or cam timing off: only likely if the engine has been worked on recently. If you removed the distributor, there is a good probability that you installed it 180 degrees out of time.
    D.) Firing order off: HO & 351 use a different firing order from the non HO engines.
    HO & 351W 1-3-7-2-6-5-4-8
    E.) No start when hot - Press the throttle to the floor & try starting it if you get this far. If it starts, replace the ECT.