2013 GT500 random start issues after warmup

Discussion in '2007+ Mustang GT500 Tech' started by luillo, Mar 4, 2020.

  1. luillo

    luillo forum member

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    Hey team S197. I have been out of the scenery for a long time since I sold my 2011 5.0, but just yesterday I bought an used 2013 GT500 and today I am having some issues I am not familiar with. Long story short, the car feels like a normal 5.0 as far as power level but it might be me and the long time I don't drive a mustang. if I am cruising in fifth gear around 70mph and push the gas pedal to the floor the gar slowly climbs up and studently rpms shoot up. That makes me think maybe the belt and tensioner are slipping or something.

    The real issue is that after the car is warm or hot, I turn it off to go anywhere for 5-10 minutes and when I try to start the car it is super rough and sometimes it turns off, like limp mode. IF the car stays on very rough, I cant accelerate at all because is like in limp mode. I have to turn it off and restart it then is good to go like nothing happened.

    Today it did it just like that but additionally the wrench light came on and after I turn it off and on it disappeared. No DCT codes stored or found when I checked with the OBD2 in AutoZone.

    Anybody have a suggestions before I take it to the Ford dealership and they rape me for basic diagnostics? I have never worked on supercharged cars or GT500s yet.
     
  2. bujeezus

    bujeezus forum member

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    If your rpms are going up but your speed isn't, that sounds like a bad clutch to me. Don't know about the starting issues though.
     
  3. Dino Dino Bambino

    Dino Dino Bambino I have a red car

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    OK. First off you have 662hp and an '11-'12 5.0 produced 250hp less, so your car should feel a lot faster than a normal 5.0.
    The rpm suddenly shooting up when you depress the accelerator in 5th suggests that your clutch is slipping. It's likely the clutch friction plate is badly worn.
    Your rough running after a hot start suggests that you could be getting fuel vaporizing in the fuel lines due to heat soak. The vapor lock is what causes the difficult starting and rough running. You could try insulating the lines with DEI Cool Tape, and have the exhaust manifolds ceramic coated to reduce radiant heat.
     
  4. MrAwesome987

    MrAwesome987 forum member

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    I agree, sounds like you need a clutch. I had a similar issue with the stock clutch in my car. In 1-3rd if felt relatively normal, but if you put it in 4th and floored it, the RPM would go up but the car wouldn't accelerate.

    The GT500 should feel like a space ship compared to the 5.0....
     
  5. stkjock

    stkjock ---- Madmin ---- Staff Member Administrator Super Moderator S197 Team Member

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    I agree sounds like clutch slipping

    is the car stock?
     
  6. luillo

    luillo forum member

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    Well, I went out today after I returned from Orlando and tested the car. It is definitely the clutch. I put some abuse into it and then tested the car in high gear and heavy load and it slips like a bitch bad, then horrible burnt clutch smell.

    I will check the other issue later after I change this crap out. No I need a good shop to do the job in or around Fort Walton Beach Florida area because I don't have my tools and last time I change a flywheel and clutch in an S197 it was pain in my ass.

    Thanks for the help guys
     
  7. luillo

    luillo forum member

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    I just wanted to add an update. I think I found what happened with the random limp modes I had with the car. Due to the clutch slipping I found out the PCM detects it and puts the car into limp mode. I found relevant information on another forum and I wanted to share here. The problem cleared after the clutch install. The symptoms were described word by word on the other forum aiming at the clutch issue.

    If the clutch slips the PCM detects it and sends the car into limp mode. That is why at the next startup of the car it was rough and as soon as you turn off the car and turn on, it was fine.
     
  8. 1 Alibi 2

    1 Alibi 2 If not today, when ??????

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    If the car came with an owner's manual & supplement, they are worth reading..
     
  9. Juice

    Juice forum member

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    Agreed. Pcm will throw it into limp mode if it detects clutch slippage.
     
  10. luillo

    luillo forum member

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    None of those in mine. but I did found a supplemental PDF online and I saved it. is very basic anyways.
     
  11. luillo

    luillo forum member

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    Well, I kind of found what might be the car issue after all and the feel of lack of power. Decided to change spark plugs with fingers crossed but go some clues that I might have some damage.

    Found 2 wet plugs. One not too bad but the driver side second to last towards the driver wet dripping oil and one side of the porcelain was ate up.

    I changed them all and gapped about .034 to .035 but those plugs gave me the feeling that something is not good there. Next ill take it to the shop for a leak down test. Hoping that the short block is good so I only have to work on heads.
     
  12. Dino Dino Bambino

    Dino Dino Bambino I have a red car

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    Do you have catch cans fitted to your engine? Perhaps you have oil getting into the intake manifold and contaminating the spark plugs. Might be something to look into if compression/leakdown tests turn out to be normal.
     
  13. luillo

    luillo forum member

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    I have one on the passenger side but I doubt the lack of one in the driver side would only wet two cylinders. The one spark plug was dripping oil when I took it off, even after a few hours that I dried it still was wet. Also it has white deposits. I will try to post the short video I have.
     
  14. Juice

    Juice forum member

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    Broken porcelain is from detonation.
    Was this car tuned?
     
  15. luillo

    luillo forum member

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    No tune. 100% stock 34K miles. I bet the prior owner race the car but I don't see for how long with only 32K miles when I got it.
     
  16. Juice

    Juice forum member

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    Time to take a peek inside those cylinders with a bore-a-scope.
     
    Midlife Crises likes this.
  17. luillo

    luillo forum member

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    Maybe, but me living in an apartment complex at the moment makes it undesirable. I will take it to the shop I trust for at least a diagnostic and see what is needed.

    If is something up in the heads, then great I will go stage 2 heads and cams from Modular Head Shop and do any other upgrade needed to help lower boost and add power.

    If is the cylinder even if is just the rings, then I will wait a little longer to get a full long block built for power all at once instead of opening the engine multiple times. For now I will finish the rear end, suspension and any other things I need on the car.
     
  18. Juice

    Juice forum member

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    Signs of detonation in a boosted car is never a good thing. I would not be surprised to see cracked pistons.
    Its hard to figure how a.head issue can cause that much oil.
     
  19. Dino Dino Bambino

    Dino Dino Bambino I have a red car

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    Yeah that's my fear too. Who knows how the PO treated the engine but it does seem to have detonated, and oil blowby in only one or two cylinders does point to broken ring lands.
    A borescope will confirm or rule out the diagnosis in addition to low cylinder compression.
     
  20. luillo

    luillo forum member

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    I know, I'm just trying to keep it positive. lol!!
     
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