HELP! 1992 Mustang OEM computer vs aftermarket computer
05-14-2016, 10:18 PM
#1
Thread Starter
Join Date: May 2016
Location: AZ
Posts: 3
HELP! 1992 Mustang OEM computer vs aftermarket computer
My car currently has an aftermarket computer. I'm in the process of switching it back to an original OEM computer, and then getting a dyno tune once I find a local tuner. When I hooked up the OEM computer just to check it, the idle was a bit rough and the AC wouldn't blow any cold air. The AC is in working order because I just had it redone with R134, and it blows cold with the aftermarket computer. Is there any reason why the AC won't run with the OEM computer? Could it be that the OEM type computer had its settings altered to turn "off" the AC somehow? Thanks guys!!
05-15-2016, 11:31 AM
#4
Thread Starter
Join Date: May 2016
Location: AZ
Posts: 3
The aftermarket one is a Megasquirt. The AC works fine with that computer. When I plugged in the OEM Ford computer, the AC doesn't work.
05-15-2016, 03:14 PM
#5
2nd Gear Member
Join Date: Dec 2014
Location: Georgia
Posts: 225
https://www.diyautotune.com/support/...r-mustang-5-0/
According to this article for your year a few pins are changed along with a handful of sensors. Looks like a wider range MAP is used which will make it idle funny because the stock PCM can't read that much range without a remap or maybe not at all (I'm not too familiar with OBD1 cars. I'd contact them directly and tell them what you have and see if they can provide you with a wiring diagram and find a diagram of the stock PCM harness online and compare. Also as for the A/C not sure if that year had a PCM trigger wire or not. But seeing as it works with the aftermarket and not stock I'd say it does and that pin has been moved. Any particular reason your going back to stock? I don't know too much about that particular brand but that should be an upgrade over stock and will allow any future mods to be tuned much more easily/safely.
According to this article for your year a few pins are changed along with a handful of sensors. Looks like a wider range MAP is used which will make it idle funny because the stock PCM can't read that much range without a remap or maybe not at all (I'm not too familiar with OBD1 cars. I'd contact them directly and tell them what you have and see if they can provide you with a wiring diagram and find a diagram of the stock PCM harness online and compare. Also as for the A/C not sure if that year had a PCM trigger wire or not. But seeing as it works with the aftermarket and not stock I'd say it does and that pin has been moved. Any particular reason your going back to stock? I don't know too much about that particular brand but that should be an upgrade over stock and will allow any future mods to be tuned much more easily/safely.
05-16-2016, 10:10 AM
#7
Thread Starter
Join Date: May 2016
Location: AZ
Posts: 3
05-16-2016, 10:19 AM
#8
2nd Gear Member
Join Date: Dec 2014
Location: Georgia
Posts: 225
What do you want to know about tuning it? If it's running correctly it should be fine unless you add mods to it. Any decent dyno tuner should be able to right tunes for that PCM. Check out their website they should have some documentation on how it all works.
05-16-2016, 10:57 AM
#9
6th Gear Member
Join Date: Mar 2010
Location: Wisconsin
Posts: 5,061
What's your mod list ? I'm assuming some work has been done to justify the cost of the Megasquirt.
Is your car not running properly now that your looking for a fix ?
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