Engine Power Steering; The Engine Killing Vampire?

Discussion in '1994 - 1995 Specific Tech' started by joetrainer31, Feb 18, 2014.


  1. joetrainer31

    joetrainer31 Member

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    My motive in posting this little write-up is to help someone out there who might be a little stumped (like I was) about their power steering adversely affecting their 94/95's idle. Yes, this is not rocket science, yes there are more interesting posts out there, yes one can gather all the necessary info for this problem from various sources on the net, but my hope is to consolidate all the info right here. I'd like to save the next guy some trouble if possible.

    So then, I've read it a thousand times, "my car dies, or almost dies if I try to turn my steering wheel while sitting still." I've also heard a thousand times in answer to such a complaint, "that's just the nature of the beast with Ford pumps," or, "your pump must be going bad."

    The good news is that there are answers that won't break the bank and won't keep your car on jack stands for weeks. The good news is that it is not the nature of the beast for your car to die when turning the steering wheel as if the pump was sucking the vary life blood out of the engine. Image how many 94/95 Mustangs Ford would NOT have sold if they came off the lot with that problem.

    So, if this is happening to you is your pump going bad? Maybe. Does it whine loudly? Is the fluid black? In my case the fluid was black, the pump whined, and my car died if I attempted to turn the wheel while sitting still. Here are the steps I suggest for you to try:

    1) If you want to try and save the pump, disconnect the pwr steering return line @ the cooler (under driver side of rad), in order to drain the fluid. This return line spans from the pwr steering cooler to the pump.

    2) Reconnect line and fill the pump with ATF type F, not Mercon or Mercon V. The owner's manual specifies this kind of fluid as the acceptable equivalent of motorcraft power steering fluid.

    3) With the car started & cap off the pump, slowly turn steering wheel w/o hitting the lock out in order to work out the air and work in the new fluid. Fill as needed, let it idle for a few minutes, repeat. If the whine and power sucking tendencies have dissipated, congratulations. You have bought your pump some more service life for the price of 2qts fluid.

    If the above did not work...

    1) Rent a pwr steering pump pulley puller and follow the online Haynes directions for pulling the pump (Autozone or Oreilly websites).

    2) Replace w/reman pump (Masterpro or Cardone w/reservoir).

    3) For piece of mind, replace the high pressure and return lines too. Try to get the high temp return line.

    4) Follow directions above for refilling the system & flushing air pockets out.

    5) When the system seems full. Test drive the vehicle.

    But it still stalls when turning the wheel at idle?!

    From what I've read online, this is not uncommon. Furthermore, the stalling is not always pwr steering pump related. Sure, your pump needed to be replaced, but that was only "a" problem, not "the" problem in many cases.

    So, let me continue with this: there is NO pwr steering pressure switch to check. In many cases, not unlike my case, when the pump, lines, and fluid have been replaced, and after the system has been bled properly, the car can still stall when turning at idle. Usually this is NOT from the pump. It is from a poorly maintained/adjusted base idle & TPS voltage setting.

    Since there is no pressure switch in our pwr steering to compensate for the parasitic drag on the engine when actuating the pump, our ECUs rely upon engine rpm to sustain power draws from the steering pump. If your base idle is too low, your car will stall when turning the wheels at idle regardless of your pump's "newness."

    Setting the base idle is super simple:

    1) Warm car to normal operating temp. That's the "R," in "NORMAL."

    2) Turn car off & disconnect (-) battery for about 30 minutes. No, your car will not completely cool off in 30 minutes.

    3) Disconnect IAC pigtail.

    4) Reconnect (-) battery.

    5) Start car and observe idle speed. (You may need to keep your foot on accelerator to warm vehicle up to the "R" again. You also may see that your car will not run w/the IAC unplugged).

    6) If car will not idle w/IAC unplugged then turn the little threaded bolt on the pass side of the TB clockwise little by little until the engine can sustain a minimal idle. Note: the set screw is NOT under the rubber plug on the driver side of the TB. That allen head adj is not needed.

    7) I found that by turning the threaded bolt until my idle hit about 675 (i.e., the highest setting before idle surge w/a 75rpm buffer) worked well.

    8) Turn car off, but keep the key in the KOEO position.

    9) Check TPS w/digital multimeter for proper voltage (.97-.99). This step is important for a number of reasons, but it is enough to say that your TPS setting can easily change when you adjust your base idle. However, save yourself some time and check the voltage BEFORE you pull things apart. It may not have changed. To check the voltage you must probe the top 2 wires in your 3 wire TPS. The top wire is the ground, the 2nd wire is for your voltage check. If all is within range go no further. If your TPS is not within range then remove your IAC, get a stubby Phillips head, & begin loosening the TPS screws just enough to get some play out of the sensor. As you adjust the sensor's position you will see the voltage change on your meter.

    10) After your TPS is set, turn the key off, reinstall the IAC if needed, and plug the pigtail back into the IAC.

    11) Start car w/all accessories off and let it idle for about 2 minutes. Turn car off for a couple of minutes.

    12) Next, start car again, then turn on all accessories and let it idle for 2 minutes. Then, turn accessories off.

    13) Next, w/accessories off, turn your steering wheel and observe that your car does not stall any longer.

    14) Lastly, turn all accessories on, let car idle for a couple of minutes, turn wheel and observe no stalling.

    15) Drive car and enjoy!

    I hope this basic write-up was helpful with your power steering woes.
    #1
  2. toyman

    toyman SN Certified Technician

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    The reference to adjusting a stock TPS is wrong for the 94-95 years . These model years do not have elongated screw slots like the earlier years and cannot be adjusted. Ideally the TPS voltage should be about 1v KOEO, however the ECU will recognize an idle voltage between 0.6v - 1.25v. If the TPS voltage is close to the outside limits I would be inclined to replace the TPS.
    #2
  3. jrichker

    jrichker StangNet's favorite TOOL SN Certified Technician Founding Member

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    Your base idle setting procedure is incorrect...

    You guys with idle/stall problems could save a lot of time chasing your tails if you would go through the Surging Idle Checklist. Over 50 different people contributed information to it. The first two posts have all the fixes, and steps through the how to find and fix your idle problems without spending a lot of time and money. I continue to update it as more people post fixes or ask questions. You can post questions to that sticky and have your name and idle problem recognized. The guys with original problems and fixes get their posts added to the main fix. :D

    It's free, I don't get anything for the use of it except knowing I helped a fellow Mustang enthusiast with his car. At last check, it had more than 134,000 hits, which indicates it does help fix idle problems quickly and inexpensively.
    #3
  4. joetrainer31

    joetrainer31 Member

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    Thanks for the info on when to replace your TPS.
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  5. joetrainer31

    joetrainer31 Member

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    Thank you for your link. I'll certainly save it in my tech file!

    All I can say for my description of the base idle reset is that it came from reading the instructions that I found on various blogs. It worked for me the 1st time w/o issue.

    I see that your link is certainly more involved and technical. However, I did mention at the beginning of the write-up that it was basic. I assume in the write-up that the reader's IAC & TPS are in proper working order.

    One of my points in writing was to illuminate the reader that failure to sustain an idle while tuning the wheel while sitting still is not always due to a bad steering pump. My intent was not to write a treatise on the TPS & IAC. Besides, you have already done that, and have done a better job than I can. I simply wanted to help someone find a quicker solution to a problem like I had (i.e., help them think outside of the pwr steering pump).

    Thanks again for your input.
    #5

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