I think I found the problem (High idle)

Discussion in 'Fox 5.0 Mustang Tech' started by eagle87, Oct 29, 2004.


  1. eagle87

    eagle87 Member

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    For a year I've been searching, poking, troubleshooting and bothering a lot of people on this board (thanks for all your help) on a code 32 (evp, egr valve problem) This is where it gets Interesting. To troubleshoot this I had a high idle up around 1500rpm Come out of the store turn the motor back on and the idle was fine never could figure this out. Run the motor get on it a bit and it would flash a code 32. Changed the evp,egr valve no help. watch the vaccume while driving even the voltage off of the computer the voltage would never go below .67. I could never get a answer to this problem either. One day on my way to work the motor starts to buck real bad I need a saddle. I check the codes it was a 63 low voltage to the TPS. I had a spare so I changed it, NO HELP It Bucked all over the place. I checked the voltage while driving, the voltage droped like a rock,I never saw a tps go negative voltage before. When I changed the TPS I cleared the computer when I had the second code 63 i checked the codes the code 32 was gone only the 63 was there. I watch the evp voltage with a meter while driving, It was a miracle the 32 was gone after a year and it was acting like it should, voltage change go down on the peddle and the voltage would go up it never did this before. I got another TPS changed it again and got a code 63 and the voltage went negetive again even stayed at 0.0 for a while. This has got to be a computer problem I'm going to change the ecm one proble does not fix itself start another one and be three TPS's no DAMM way. The computer can't keep up with the info I'm getting a new one tomorrow I'll let you know how I make out. OH the high idle went away When it runs it idles great like new ....... Sorry its so long this is a years worh of crap Later :bang:
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  2. jerry beach

    jerry beach Founding Member

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    Do you have the Charles Probst book? You seem to know what you are doing from what I read in your post. I suggest that you unplug the computer and ohm out the wires between it and the TPS. It may very well be the puter, but make sure its not the wiring first. Take care.
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  3. eagle87

    eagle87 Member

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    No Book Jerry I get it form hanging around here. I started the motor and did a wiggle test to see if the voltage would go wackey, It stayed solid. The weird thing is it will start out ok it will run. I'll go about 5 to 10 miles and then it will start Bucking real bad, It so bad it can make the CD skip in the player This is when the voltage goes to zero. I will do the test you suggested thanks foe the reply JOE........ Also my Gas mileage was for crap. My fuel regulator went it was something like 68 pounds for god knows how long I looked at the o2 sensors while running before I replaced it and after the voltage reading while bounceing back and forth never changed .3 to .8.
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  4. jd351

    jd351 Founding Member

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    A friend of mine suffered for a couple of years from a simular problem. Ended up being a bad terminal at one of the harness connectors. The +5.0V signal wire going to these sensors had LIGHTLY(very lightly) corroded and was giving him heck...

    Anyway a good local shop that specializes in Mustangs (Brad's Custom Auto)spent 10+ hours on it, after we had already changed every sensor, the EEC, every relay, seloniod, etc. (I had a lot of spare parts) They did a wire by wire trace to find it.

    When he gave them the car, he told them, "whatever it costs I don't care, just fix it". Anyway at $85 dollars an hour it cost him $170, bad math? No! They had several customers with simular/same problem and used his car as the test mule. Knowing we had done all that work allready, and being confident all the parts were up to snuff, they knew this was thier best chance to find it. Anyway, the day he picked it up they had 5 more mustangs that were in the proccess of, or completed, the same terminal replace. ALL were fixed by this one repair!

    The terminal replaced is in the connector at the engine to firewall plug.
    start there, and good luck.
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  5. eagle87

    eagle87 Member

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    Thanks JD If it starts again thats where I'll go. So far all day it hasn't done it and the idle is GOOD, I never had a good idle I Forgot what it feels like. So far no check engine lights either.
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  6. hardimam

    hardimam New Member

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    1990 mustang 5.0 t5

    I have the code 32 67 31
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  7. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    A search would have brought up the Surging Idle sticky & item #6 on the checklist... 10 Pin salt & pepper shakers...

    See the "Surging Idle Checklist for help with all your idle/stall problems. The first two posts contain all the updates to the fixes. At last count there were 24 possible causes and fixes] for surging idle/stall problems. I continue to update it as more people post fixes or ask questions.
    #7
  8. hardimam

    hardimam New Member

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    1990 mustang 5.0 t 5

    i still get code 67 and the check engine light come on in off i clean black and white plug and my voltages went up
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  9. hardimam

    hardimam New Member

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    1990 mustang 5.0 t 5

    my check engine light come on when i start the engine and it go's on an off when i go to hit the gas. It come on i check the code is 67 can you help me
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  10. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    Code 67 - clutch not depressed (5 speed) or car not in neutral or park (auto) or A/C in On position when codes where dumped. Possible neutral safety switch or wiring problem. This code may prevent you from running the Key On Engine On tests. You can generally ignore this code, since it has no effect on engine performance.

    The computer wants to make sure the A/C is off due to the added load on the engine for the engine running tests. It also checks to see that the transmission is in Neutral and the clutch depressed (T5, T56, Tremec 3550 & TKO)). This prevents the diagnostics from being run when the car is driven. Key On Engine Running test mode takes the throttle control away from the driver for several tests. This could prove hazardous if the computer was jumpered into test mode and then driven.

    The NSS code 67 can be bypassed for testing. You will need to temporarily ground computer pin 30 to the chassis. Computer pin 30 uses a Lt blue/yellow wire. Remove the passenger side kick panel and then remove the plastic cover from the computer wiring connector. Use a safety pin to probe the connector from the rear. Jumper the safety pin to the ground near the computer.
    Be sure to remove the jumper BEFORE attempting to drive the car!!!
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  11. hardimam

    hardimam New Member

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    1990 mustang t5 5.0

    Thanks for the help, but i still need more help. I need to know would code 67 have my check engine light come on. When I first start up the car the check engine light comes on and blinks off and then it comes on again. Then when i accelerate between 2000- 3000 rpms the check engine light comes back on. Do you know what can be causing this problem? Thank You
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  12. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    Read the code 67 test path again. You will find that there is nothing it it that says a code 67 will set the CEL. You have other problems to fix so that you can dump the Engine Running codes. Those Engine Running codes are what is making the CEL come on.
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  13. hardimam

    hardimam New Member

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    1990 mustang 5.0

    my check engine light comes on and blinks off and then it comes on it is no code
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  14. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    It's bad manners to hijack someone else's post. Please start your own post and I will try to help.

    Please use proper punctuation so that your post is more readable. If people think you are ignorant, they won't waste their time trying to understand your problem or try to help.
    #14

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