Engine Hesitation Complication

Discussion in '1994 - 1995 Specific Tech' started by joetrainer31, Apr 1, 2013.


  1. joetrainer31

    joetrainer31 Member

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    1st time poster, long time mustang owner here. So I just purchased my first SN95 GT Convt. It only has about 64K miles on it. However, it has a hesitation problem. This problem occurs at low speeds and at times while trying to accelerate at highway speeds. Furthermore, the vehicle seems all-around lethargic.

    I have observed the following modifications: SVO intake, under drive pullies, 160 or 180 thermo (judged by eng temp), 373s, shorty headers, 65mm throttle body, flow master cat back.

    I have performed the following services since buying the car 1 week ago: oil change, new plug wires, Berryman's 2 step combustion cleaner, redline in gas, changed pcv-metal screen-grommet, cleaned MAF w/CRC MAF cleaner, cleaned TB w/CRC TB cleaner, Rad & Block coolant flush, multi meter check air intake temp sensor, removed MAF screen, replaced Air Filter, Replaced Fuel filter, checked fuel pressure at rail (40psi line off). I checked 2 spark plugs: pass side rear/driver side frt; both looked new.

    I have noticed: High pitched whine from fuel pump. Also, there is NO check engine light popping.

    Please help. Any insight out there?
     
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  2. Noobz347

    Noobz347 Stangnet Facilities Maint Tech... Er... Janitor Admin Dude

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    Pull codes first. Check TPS 2nd. Look for poss vac leaks.
     
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  3. joetrainer31

    joetrainer31 Member

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    Ok. Thank you. I have a couple of follow up questions.

    1) I have no check engine light. Will there be codes to pull w/o a check engine light?
    2) Checking TPS means checking it with a multimeter? If so, what should I see?
    3) I certainly hear no leaks, but I will check for them. Where is the best place to check & what should the Vac reading be if there are no issues?

    Thanks so much for any further advice you are able to give.
     
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  4. toyman

    toyman SN Certified Technician

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    Possibly. CEL lights are primarily emissions related. Other codes are stored.


    You should see a smooth steady increase in voltage from about 1v to 4.8volts

    Vacuum should be steady around 20 in. Vacuum lines and potential leak points are often hidden, so detecting leaks short of smoke tests can never be 100% certain.

    Very important. The battery to engine and engine to chassis grounds are critical for all engine sensors to function properly so they must be solid.
    With respect to the fuel pressure it needs to be confirmed while the engine is running as well. It should be about 35+ psi KOER.

    Keep in mind that any sensor that may be original can be suspect. They may not be bad enough to trigger a DTC but they can be slow in responding when compared to a new one.[/QUOTE]
     
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  5. joetrainer31

    joetrainer31 Member

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    [/quote]
    Thank you very much toyman [and noobz347]. I will check all the mentioned concerns. I purchased an OBD1 scanner w/extension cord from Amazon. It should be here within a day or so. When I complete all the tests mentioned above I will get back to you. Although, it make take me longer than usual because I am still in semester at school.

    In regard to your [toyman] comment about fuel pressure; I checked it KOER (w/line off) and it was a steady 40psi. I also checked it KOER (w/line on) and it was a steady 32psi. However, the pump does whine. In my old fox body this was usually indicative of a pump going bad. I heard that it is more "normal" in an SN95. Is this correct?
     
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  6. joetrainer31

    joetrainer31 Member

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    Thank you very much toyman [and noobz347]. I will check all the mentioned concerns. I purchased an OBD1 scanner w/extension cord from Amazon. It should be here within a day or so. When I complete all the tests mentioned above I will get back to you. Although, it make take me longer than usual because I am still in semester at school.

    In regard to your [toyman] comment about fuel pressure; I checked it KOER (w/line off) and it was a steady 40psi. I also checked it KOER (w/line on) and it was a steady 32psi. However, the pump does whine. In my old fox body this was usually indicative of a pump going bad. I heard that it is more "normal" in an SN95. Is this correct?[/quote]

    --------------------
    Update #1
    - Using my Equus 3145 by INNOVA I have performed the following tests:
    1. KOEO (1st test) = all pass
    2. KOER (1st test) = all pass, yet almost stalled after test was finished.
    3. KOEO (2nd test) = 564 (Fan control circuit failure) although I doubt this would cause hesitation, stuttering, & general lethargy. Furthermore, the fans displayed high & low speeds regardless of code.
    4. Relay & Solenoid test = all pass
    5. Cylinder balance test (performed twice) = perfect score/all pass.

    I have to wait for the engine to cool down before I can pull the pcv & proceed w/the next test.
     
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  7. joetrainer31

    joetrainer31 Member

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    Update #2 Out of curiousity I checked my spark numbers. I physically inspected them a couple of days ago and they looked fine. However, I'm wondering if the following plugs are correct for my car (Chapion RS14YC6). I had purchased simple Autholite 25s but I noticed that they would not screw into the head. What's going on here?
     
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  8. joetrainer31

    joetrainer31 Member

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    Update #3. The car has iron GT40 heads, thus the autolite 25's do not fit. I'll need autolite 764's.
     
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  9. toyman

    toyman SN Certified Technician

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    Fuel pressure KOER @ 32 psi is fine. If all other things check out okay I would look to first replacing the MAF if it's the original one. With respect to "the vehicle seems all-around lethargic" statement, what gears do you have? 2:73s will definitely give a lethargic feeling.
     
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  10. joetrainer31

    joetrainer31 Member

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    Good morning toyman & thank you for your response. My agenda for today is:

    1. Replace coolant temp sensor (easy to replace & weedout of the equation).
    2. Install Autolite 764's (I'm not familure w/the curent installed plugs).
    3. Attempt to resolve my KOEO 564 code.
    4. Check ignition timing.
    5. Check ignition module.
    6. Check MAF meter (I'll 1st unplug it and observe the car's behavior under driving conditions).
    7. Continue performing deeper layers of OBD1 code pulling.

    My gearing seems to be 3:73s. I've had that gearing before & this seems the same. Question: I'm still suspecious of the fuel pump. Yes, the fuel pressure is solid, but the pump whines a lot. In fox body cars that means pump death is approaching. Is it acceptable for 95s?
     
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  11. Chythar

    Chythar Well-Known Member

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    If you're going to replace the Coolant Temp Sensor, you may want to replace the Engine Coolant Temp sensor as well. Our engines have two temp sensors: the CTS feeds the dash gauge ONLY. The ECT feeds the computer, and if it's giving a bad signal the computer will pull timing trying to cool off the engine.

    The fan control circuit is in the CCRM module, the black box on the bracket that holds the coolant overflow tank. The same module also controls electrical power to the engine, so it's possible that's your issue as well. The 564 might be caused by bad wiring or a short. Hissin had a nice writeup on how to test the CCRM, at least on how to test the fan circuit. Perhaps he can chime in with some input.
     
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  12. joetrainer31

    joetrainer31 Member

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    Thank you for your input Chythar. I replaced the coolant temp sensor that is in the coolant rail, on the passenger side of the vehicle. I believe that it is the one that signals the computer. I saw the other one sticking out of the manifold closer to the driver side (goes to gauge). I have not repaced it yet. The gauge still moves though.

    I did not get all of my agenda completed today, but I did pull the pigtail off of the CCRM a spray it and the CCRM with elec contact cleaner. When I unbolted it, it seemed like it was a little loose. We will see if there is any improvement after I pull codes again.

    I also pulled a 411 & 412 code on my load test. Therefore, I removed the IAC, cleaned it thoroughly, cleaned the elec connections, repaired two exposed wires, then reinstalled it. Upon removing the IAC I noticed that the bottom bolt was not properly tightened. Therefore, I made sure that everything was tight upon reinstallation. We will see how it all goes. I have the battery completely disconnected so that the ECM will be completely clearned when I go to test again.

    I value the help that you all are so kind to offer me. Thank you.

    [email protected]
     
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  13. Chythar

    Chythar Well-Known Member

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    You did replace the one that the computer reads, the ECT. The one screwed into the manifold is definitely the CTS. You can buy a code reader that will read several sensor values while the engine is running, but that tool will cost you over $200.
     
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  14. joetrainer31

    joetrainer31 Member

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    Yikes @ $200. For now, I'm avoiding death by wife for the repairs I'm doing. I have a cheaper scanner at the moment. I think I'll just use a multimeter to check voltage on some sensors for now, but thank you for the heads up.
     
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  15. joetrainer31

    joetrainer31 Member

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    image.jpg

    Ok,so there were 2 issues. One, was a slammed full IAC which was not even installed securly (vacuum leak). Two, was a bad CCRM. The CCRM on the left is the refurbished unit from ebay. The one on the right is the old unit.

    When I plugged in the refurbished unit it was like a new car. Thank the Lord. The car came alive. As an unexpected bonus: I though maybe my fuel pump was going bad because it was so loud, and because of the hesitation/stuttering. However, with the new CCRM the pump is easily half as loud as it used to be, and there is no stuttering (vacuum fix probably helped the stuttering though).

    I plan on having a friend, who is a professional electronics repair/builder, refurbish all the relays in the old CCRM unit. Maybe it will go up for sale. Maybe it will be a spare. Any thoughts guys?
     
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