95 5.0L horrible engine and driveability problems. HELP!

Discussion in '94-95 5.0 - Specific' started by MrBones, Jan 3, 2020.

  1. MrBones

    MrBones New Member

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    My 95 5.0 GT I built is running really weird. Before getting up to temp it bogs down and wants to stall. When it is up to temp it bogs down and stalls when putting it in gear. I have to give it gas just to keep it running. When I do give it gas it usually hangs around 2,000 rpm. It doesn't snap back down like it should. The smell of the exhaust is so rich it's nauseating.

    I'm really racking my brain on what this could be. It doesn't seem simple. I do not even know where to take this car if I were to take it to a shop. Seems there is something very wrong.

    Here is a video I took of a recent cold start up, the whole build is also in the description:


    PLEASE HELP
     
  2. evilcw311

    evilcw311 Moderator Staff Member Staff

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    Either you have a major vacuum leak or your iac valve took a dive.


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  3. MrBones

    MrBones New Member

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    Ughhh I’ve went through the intake and all gaskets a few times. Could it be because of it being so modified? It shouldn’t be doing this on the base tune right?
     
  4. Connie

    Connie New Member

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    I had a Idle problem a while back, on my '03 GT. The Idle Air Control Valve was going bad. But, it never got to the point your at. I just threw a new one on, and it cured the issue. They don't cost that much, and if your IAC has not been changed in a long time, listen to evilcw311. It's also preventive maintenance.
     

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  5. evilcw311

    evilcw311 Moderator Staff Member Staff

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    It could be leaking from many places, plastic vacuum lines, rubber vacuum lines. Easiest test is the smoke test. If no leak is obvious then replace your iac. Mine went bad once and caused the exact same thing. Sometimes you can take yours off and clean it really good and then lightly oil the inner spring and it will start working again. Unfortunately parts stores iac’s are not always very good.


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  6. PinkieT

    PinkieT Well-Known Member

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    What he said. I had similar problems and it ended up being a bad throttle body gasket . Vacuum leaks will really mess with you.
     
  7. 2002BLGT

    2002BLGT Active Member

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    Smoke test is best way to check for vacuum leaks
     
  8. wbrockstar

    wbrockstar New Member

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    A maf sensor,vacuum leak,iac valve or ect issue seems likely to me due to the symptoms.

    Disconnect the harness from the maf sensor first then try starting the engine to see how it runs.If it runs drastically better,the maf should be cleaned and tested.If this check doesn't show any improvement, move on and check for vacuum leaks.
    A vacuum leak creates a lean condition,which oftentimes causes a rough,surging or high idle condition, stalling,hesitation,misfires,etc. Hoses,gaskets,vacuum operated components,brake booster check valve/grommet,pcv valve,smog solenoids,intake gaskets,injector bosses,etc are all areas of concern where a vacuum leak can occur.I don't know about the SN95,but the Foxbody was terrible about dry rotted hoses between the charcoal canister & purge valve.Speaking of the purge valve: if it gets stuck in the open position,this will allow unmetered fuel into the engine.Im not sure how well it'll work,but for the vacuum leak check,pull the hose off the brake booster check valve, light a cigar and take a good inhale of smoke (without choking of course) then blow the smoke into the hose.Any items leaking vacuum should allow the smoke to escape where you can hopefully see it.If you would rather use a different method,
    the video in the link at the bottom shows how to build a makeshift smoke machine for $15.If you don't locate any vacuum leaks,move on to the next items.
    The iac valve & ect sensor are the two primary components used during cold starts that prevents the engine from stalling.If the iac doesn't open fully and/or the ect doesn't output a cold temp reading (which richens the fuel trim) during cold start,a rough idle or stalling normally occurs.It works similar to how a choke works in carbed setups.The iac valve is directly affected by the ect sensor,so if the ect is suspect, the iac will likely not function correctly.When the ect outputs a cold temp reading,the iac is opened.When it outputs a warm reading,the iac is closed.The ect can be checked by disconnecting its harness and touching meter leads to the sensor terminals to test its ohms reading.Test it cold then hot & check those values against the ect/act ohms/temp chart.The iac can be checked too.Check it to see if its dirty first.If it is,it should be cleaned. For testing: with multimeter leads connected to the iac valves terminals,with the harness first disconnected,the meter should read 7-14 ohms in one direction & OL or Infinite in the opposite direction.Now hold one meter lead directly to the iac body while you move the other lead between the two iac terminals individually.The meter should read OL or >1meg ohm for both terminals
    For the wiring,the red iac wire should read 12v.The white/lt blue wire is cycled to ground many times a second.


     
    Last edited: Jan 7, 2020
  9. Werecow

    Werecow Member

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    I even found a vacuum leak on my IAC valve when I took it off, as it had a crack in it and the gasket that was used by previous owner was torn, causing a leak right in the throttle body... Sometimes it just takes a lil Dick Tracy work and a can of parts cleaner even, tho not around hot parts... Safety first, right guys and gals!!! Cheers!!
     
  10. lwarrior1016

    lwarrior1016 Moderator Staff SN95 Supporter

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    I really hope your gauge cluster is wrong, because it shows you over charging and no oil pressure.
     
  11. Werecow

    Werecow Member

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    My gauges are frakked up.. man I really need to take some shots of mine with koeo, koer so youse guys can sees what I mean...I do however have 1 gauge that works.. that's my vacuum gauge that I have plumbed into the bottom of the upper plenum!! Gotta have that 1 working!!