New PCM Idle Issue
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3rd Gear
Joined: Sep 2024
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New PCM Idle Issue
Hello all,
I have a 94 F150 with an E40D and a 5.8.
I recently replaced my PCM with a VIN verified unit from Protech Auto in a attempt to resolve a transmission shifting issue.
Unfortunately this did not resolve my shifting issue and my truck has started to fast idle after every start since installing the new PCM. The truck used to fast idle only after the first start of the morning then kick down to about 800 but now it fast idles after every start even after I drive it for a while. The truck still kicks down on its own but I find it strange that this never occurred before.
I know it’s easy to assume that I need to pull the PCM and have it sent back for warranty but I was curious if there is something else that could be at play before I go through that process? I replaced the IAC and the TPS about a year ago and I was not experiencing this issue with the old PCM, although it was very corroded when I removed it.
thanks in advance.
I have a 94 F150 with an E40D and a 5.8.
I recently replaced my PCM with a VIN verified unit from Protech Auto in a attempt to resolve a transmission shifting issue.
Unfortunately this did not resolve my shifting issue and my truck has started to fast idle after every start since installing the new PCM. The truck used to fast idle only after the first start of the morning then kick down to about 800 but now it fast idles after every start even after I drive it for a while. The truck still kicks down on its own but I find it strange that this never occurred before.
I know it’s easy to assume that I need to pull the PCM and have it sent back for warranty but I was curious if there is something else that could be at play before I go through that process? I replaced the IAC and the TPS about a year ago and I was not experiencing this issue with the old PCM, although it was very corroded when I removed it.
thanks in advance.
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3rd Gear
Joined: Sep 2024
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unfortunately there were no codes being thrown with the old PCM and there are none being thrown with the new one now. The truck is running exactly the same (with the transmission issue) the only difference now is the idle. I’m just wondering if my TPS is out of wack or the new PCM is just junk. It was one of the more expensive services I went through and they guaranteed a bench test before sending it out that’s the only reason I was searching for alternatives.
Hotshot
Joined: Jun 2015
Posts: 12,883
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None at all? Not even the system pass code? What lead you conclude that the old computer was bad? Why did you replace the TPS? Test the new part to see if has failed. Did the “new” PCM have the same engineering number on the sticker as your old PCM?
Thread Starter
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3rd Gear
Joined: Sep 2024
Posts: 3
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Hotshot
Joined: Jun 2015
Posts: 12,883
Likes: 2,447
The computers are preprogrammed from the factory. They are not programming them in house from your VIN. It isn’t like an OBD-II computer that you flash to update it. So are you getting the system pass code or not?
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