Odd, uneven idle problem at startup - Ford Powerstroke Diesel Forum
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Old 03-23-2013, 03:58 PM
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Odd, uneven idle problem at startup

I just bought another Powerstroke. It is a 1997, with 319,000 miles. This is the 16th, 7.3 I have owned, but, it has a problem I have not seen before.
At startup, hot or cold, the idle is uneven for about 20 or 30 seconds. It goes from regular idle RPM down to "almost dies" RPM, then bounces right back up to regular idle speed. Does this repeatedly for about 20 or 30 seconds, then it smooths right out. If I give it a little throttle at startup, it will run smooth during startup, until I let it go back to idle.
Again, this only happens on startup, not during driving or at stop lights etc.
Otherwise, truck runs great. I drove it 100 miles to bring it home, all at around 65 - 70MPH, with no problems.
I don't think this is related, but it needs a glow plug relay most likely. The wait to start light goes off after only about 5 seconds every time you start the truck. It should be on longer than that in cold wet weather.
What is causing this.
Thanks,
Jeff
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Old 03-23-2013, 07:25 PM
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If this an automatic, does it do it if you start it in neutral? Just a note on the Wait-to-Start light: The length of time it is on has nothing to do with when the plugs are actually on (watch your voltage gauge as that will basically tell you when the plugs are on). Cheers!
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Old 03-23-2013, 07:52 PM
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It is an automatic. I will try cranking it up in neutral and see what happens. Will report back here.
Yes, I forgot all about that wait-to start light versus voltage draw, for checking how long the glow plugs are on. Thanks for reminding me about that.
Jeff

Quote:
Originally Posted by Patrick Feeley View Post
If this an automatic, does it do it if you start it in neutral? Just a note on the Wait-to-Start light: The length of time it is on has nothing to do with when the plugs are actually on (watch your voltage gauge as that will basically tell you when the plugs are on). Cheers!
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Old 03-24-2013, 09:28 AM
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Ok, today I started the truck in neutral. It idles fine when started in neutral.
So, what advice do you have for me??
Any help appreciated.
Jeff
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Old 03-24-2013, 05:08 PM
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Usually the fix (I've never had this problem myself ... just from my times on the forums) is replacement of the Transmission Range Sensor on the transmission. Cheers!
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Old 03-26-2013, 05:18 PM
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Patrick,
Thank you for that info. I am going to see about replacing that part next week. My son is going to fix it next week. He was a Ford mechanic at one time, but he never worked on any of the Powerstrokes at the big dealership he worked in. He said that this should be an easy fix.
Thanks again.
Jeff
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