Auto to Manual swap PCM question - Forums at Modded Mustangs
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post #1 of 6 Old July 18th, 2019, 05:15 PM Thread Starter
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Auto to Manual swap PCM question

I have everything I need for the swap sorted (from the same parts car), except for one thing. I am not sure how to go about the PCM situation. I know the auto pcm will "work", but speedometer will be off and cut fuel thinking its hitting the speed limiter (at around 40-60mph).It will stumble when it should shift, yada yada yada, basically a limp mode. I know PATS comes into play as everything is married to each other.

I can get the manual PCM out of the parts car (same year and everything besides trans). If I have someone flash a PATS delete in the PCM it should work with no problem, correct? PATS is the only thing that is stopping me, I believe. I will also be using the manual trans harness as well.

I have searched many forms and cannot find a definitive answer. Thank you.
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post #2 of 6 Old July 19th, 2019, 07:03 AM
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Yes it should work...and provided you're using the manual trans harness, right?

Note that with some software you can actually carry over the PATS key to the new PCM rather than disabling it. Either will work. And depending on who you go to, you might even be able to reflash your existing PCM with the manual calibration instead.
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post #3 of 6 Old July 19th, 2019, 11:18 AM Thread Starter
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I am trying to use everything from the manual car, including harness. I found someone on Ebay who say they can delete PATS. They also say that they can reflash my auto PCM to manual. He wants $75 for PATS delete and another $100 to reflash.

I think it would be better to use the manual pcm instead of refreshing, because he wouldnt be able to forget to change some of the data, and it is a hell of a lot cheaper. No one in a couple hundred mile radius of me does that type of tuning anymore, sadly.
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post #4 of 6 Old July 20th, 2019, 05:12 PM
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Just use your auto pcm and have all the auto functions turned off. Also the speedometer correction can be done right in the tune. The only difference between an auto and manual pcm is EPC (electronic pressure control ) is not in a manual pcm. All the other functions are there put not that one. Im 99% sure the pin for EPC control is not on the manual harness also.

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post #5 of 6 Old July 21st, 2019, 01:11 PM
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I have a 1996 Mustang GT was originally an auto and did the manual swap. I did not put the manual trans harness or the manual PCM. To start the car I have to crank it and spray brake cleaner and hold the rpms up. Then it has to relearn idle because it will just keep on hunting up and down and it'll just die. However once it learns idle it will stay on and start right back up. My plan is to get the Manual PCM due to it being cheaper then a flash/tune. Not sure if I'll do the trans harness as it's a drift car and as long as it runs and drifts I am fine with it. With this auto pcm it does cut fuel at like 4k rpms while drifting.

---------- Post added at 05:11 PM ---------- Previous post was at 04:16 PM ----------

I forgot to mention that the 1996 F150 also has the 4.6L motor and manual trans. I plugged in a F150 PCM and it fired right, and ran smooth. It was just flashing the theft light all the time.

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post #6 of 6 Old July 26th, 2019, 07:26 PM Thread Starter
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Thank you all for the replies and advice. I ultimately went the route of the manual pcm with PATS deleted so I wont have to worry about properly changing the pcm from auto to manual.

I dropped the auto trans pan and there is something that resembles a plumb Bob with an or ring around it. Could you aid in telling me where this sits in the trans so I can reinstall it for the next user? Thank you
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