Overdrive

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Jan 24, 2005 | 07:12 PM

Thew

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Overdrive

I have a '98 expy, 5.4L that is fairly standard (K&N FIRP only mod). Recently, the PCV tube needed to be replaced as it started to leak. After taking my expy to the Ford dealer, they recommended I update my computer, change spark plugs and clean the fuel injectors. Since I had 92,000 miles, I was ready for the 90k tune up anyway. After $820, I've been noticing that my expy in overdrive produces inconsistent RPMs when traveling 65mph. In some cases, the RPMs are at 2400, while other times they are at 1900. This is traveling the same roads, so I know it's not based on road conditions. I called the tech guy at Ford and asked him if the computer update could of altered this and he said it has nothing to do with it. Anyway, I am going for a road test with a tech later this week, but wanted to get your options of what might be happening prior to the road test. One other thing I notice, my RPMs at idle are incosistent as well. Sometime it idles at 600 while other times it hovering around 8-900 rpms. Thanks in advance for your feedback.

Jan 24, 2005 | 10:36 PM

SZAlbNM

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From: Albuquerque,NM

I wonder if the torque converter could be alternately unlocking (raising the RPMs) then locking (lowering the RPMs)

Jan 25, 2005 | 04:46 AM

High_Horse

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From: Orlando, Fla

Yes it does sound like your converter is going in and out of lock up, but that doesn't explain the idle ranging. That sounds like a sensor, TPS or the like which also affects converter lockup....not a guaranteed solution, but a starter and hopefully simple fix. Gook luck

Jan 25, 2005 | 11:41 AM

SZAlbNM

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From: Albuquerque,NM

On my '00 X, every time I let up on the throttle the TC unlocks. I'd like to know if this can be changed by tweaking the program.

Jan 25, 2005 | 03:58 PM

Thew

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Thanks for your feedback. Is the torque converter controlled by the sensors, which ultimately is controlled by the computer? Should this be the problem, it appears this might be related to my computer being updated recently. Is that right?

Jan 25, 2005 | 06:59 PM

High_Horse

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From: Orlando, Fla

Thew,
As for the update affecting it, I have no idea what was loaded, so I can't say.
Your statement of the computer controlling the tc, yes, all the sensors report back to the computer and it determines air/fuel rate, ignition advance, shift point and yes tc lockup.
Are you getting any check engine lights or is your overdrive light blinking or has blinked without you touching it.

SZAlbNM,
I have no idea whether or not that is possible, you can ask a local hot rod shop, one that works on cars, not just sells the parts.

Jan 26, 2005 | 07:24 PM

Thew

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No. I am not getting an check engine light or such. When my expy shifts into overdrive, it shifts with a lower or higher RPM as described above. When I release the OD it shifts back into 4th gear at both RPM levels. I even tried resetting my computer and appeared to do the trick for a couple days, but then went back to the inconsisent RPM when in OD.