2003 Gt Engine Failure

Discussion in 'SN95 4.6L Mustang Tech' started by Jinx, Jun 22, 2013.

  1. Well the tests I outlined earlier is the only thing I can tell you. Test fuel pressure, spark etc etc.

    Crank sensors are a big issue with Ford Modulars. They can test fine yet still not function properly. Usually though that's a no start issue. Since your car runs you need to test pressure and spark. Coils are problematic but cheap on ebay. Lastly, have you done a leakdown test or a compression test? Maybe the motor is bad. :shrug:
  2. Is it possible for the vehicle speed sensor to be faulty enough to throw off the PCM highspeed idle control, but not the cluster speedometer?

  3. Not that I know of. If your car is a stick shift you shouldn't actually need to in order for the car to properly operate. Just unplug the thing and see what happens.
  4. A glimmer of hope today.

    I found a local mechanic who is willing to think outside the OEM training manual. He has the contract with the city police department, so he is very familiar with the modular engines.

    why am I hopeful... because after I told him about all the issues and symptoms he suggested he wanted to:
    1: test the actual voltage readings at the TPS (not just have a diagnostics say it was good)
    2: suggested a test for ripple on the alternator (like stated earlier by joshjwc9 )
    3: verify the voltage reading at the IAC valve itself (not just have a computer tell him OK)
    4: wants to use a portable scanner to data log the TPS and IAC duty percent.
    5: verify the O2 sensors are sending proper signals.
  5. Sounds like a a guy who actually does troubleshooting directly. He might be able to narrow it down.

    Might be worth it to spend 50 bux on a multimeter and learn how to use it. You can save yourself a lot of time if you get good with one of those....

    Good luck with this other guy.
  6. Took the car to the new mechanic on Friday. He calls me on Saturday and wants me to come in and test drive it because he believes he's solved some of the main symptoms. He tested the IAC valve on and off the car and says that while the new valve I bought is functioning there seems to be an issue with it. He replaced it with the one from his car and the hanging issue is all but gone. He also said that the throttle plate was closing too far and that is what was causing the binding/sticking sensation in the throttle cable. He also put a meter on the TPS and said that he was able to twist it just enough and lock it down to get the voltage withing spec (nothing the other mechanics or Ford could do)

    Since I was out of town for the weekend, I was unable to drive it. So it has sat at his garage with his parts on it since Saturday. He wants me to come in on Monday a test it out. If I am satisfied he will order me a new motorcraft IAC and put it on. He wants me to drive it for a week and let him know if it needs more tweeking.

    Keeping my fingers crossed.


    Mechanic #3 had it less than 24hrs. and fixed all known issues. :rock:

    Turns out that the IAC from BWD is not properly ported for our cars. The mechanic is going to let me continue to use his until my new Motorcraft IAC valve comes in. He also tweeked the TPS and fixed the throttle valve plate position so it no longer sticks. Took it for a test run and all is normal. Looking forward to picking it up this afternoon and putting my tune back on it.

    He's also wants to give me free time on his dyno. He's been tuning imports for years and has been tuning domestics for a short while and wants to see what the difference is between stock and my custom tune.
    03_TrueBlue_GT likes this.
  8. "I love it when a plan comes together!"
  9. Glad you got it fixed. It must feel SO good to drive it.
  10. It does... to a point. I've started another thread about my missing custom tune. Car seems to be missing some of that "pep"
  11. Yeah never again will I use BWD from the auto parts stores. I bought one when my IAC was bad thinking it would be good to spend 80 bucks vs 180 for a Motorcraft one, but turns out it didn't solve the problem completely, so I went ahead and got a Ford Motorcraft one and problems all solved. Glad to read you got the car fixed Jinx.
    Jinx likes this.
  12. On more than one occasion I have bought bwd only to open the box and find a motorcraft part. Sometimes it might be worth checking to see before looking for the motorcraft box and price
    Jinx likes this.
  13. My Motorcraft IAC came in today. brought the car back to the mechanic so that he could reclaim his part and put mine on. Car runs like a champ and idles as it is supposed to. For all trouble shooting that he did, my final fee was less than $70. :nice:
    jcgafford likes this.
  14. Sounds like you have an awesome mechanic. Definitely someone I'd be a return customer for. :nice:
    trombonedemon likes this.