PCM/OBD2 issue
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8th Gear
Joined: Sep 2012
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PCM/OBD2 issue
I have a 1999 F250 5.4 Super Duty and it has been miss firing and I get crap for mileage. So I decided to plug in my obd2 scanner to try and find the issue only to have the scanner say PCM not equipped. It reads the ABS and SRS system but no PCM. Check my 1999 Explorer, 2004 Ranger and 2008 F350 to make sure the scanner works and it does. I figured alright the PCM is bad I have had this happen in my 92 ranger no problem. So I ordered a new PCM online get it, put it in and i can read it but it still feels like it miss fires my scanner doesn't pull any codes. Figured drive it for a while and check again, check a few weeks later and scanner says PCM not equipped again. So now I am wondering if I got a bad PCM or is there something else going on. Any advise would be much appreciated.
More Turbo
Joined: Jan 2019
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You are not going to get misfires with this vehicle. Your vehicle is OBD1 and reading with a OBD2 scanner is not going to cut it.
You can get Forscan software for a PC, the proper USB to OBD adaptor (the Forscan website will direct you to the proper one) and read misfires this way.
In diagnostic under "mode 6" you will perform this test and it will give you a percentage of misfires by cylinder. Look for a high percentage and that cylinder is likely your issue.
You can get Forscan software for a PC, the proper USB to OBD adaptor (the Forscan website will direct you to the proper one) and read misfires this way.
In diagnostic under "mode 6" you will perform this test and it will give you a percentage of misfires by cylinder. Look for a high percentage and that cylinder is likely your issue.
More Turbo
Joined: Jan 2019
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Well they had the California version and a Federal version.. The federal would be OBD1 and California OBD2. So I am not sure what your vehicle was set up for or what type of PCM you put in. If you had OBD2 originally it say it under the hood.
And yes the OBD1 had OBD2 port but OBD1 monitoring.
And yes the OBD1 had OBD2 port but OBD1 monitoring.
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8th Gear
Joined: Sep 2012
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This is the original PCM I replaced with a new matching one (still have the original), and I guess since the stickers dont say obd2 on the it is the obd1. I thought my scanner did both since it read it fine for over a year but I am trying to find if it said that anywhere
More Turbo
Joined: Jan 2019
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Yeah OBD1. I know that misfired are monitor to some degree (why you can see the % in mode 6). Maybe some apps or scanners can see the misfires, I am not sure, but mode 6 is what I use after trying a few apps with no success. (I am also running OBD1).
Hotshot
Joined: Jan 2004
Posts: 19,768
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From: St Louis
You will have to use Mode $06 misfire counts to see which cylinder(s) might be misfiring. The OBD1 calibration is almost brain dead in regards to posting DTCs and turning on the MIL when faults are present. See this thread: https://www.ford-trucks.com/forums/1...bd1-obdll.html
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