Electrical NEW HERE!
- Thread starter Hudson Industrial
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wmburns
SN Certified Technician
Did you ever find a set of Ford wiring diagrams and service manual? If not I maybe able to help. PM if interested.
wmburns
SN Certified Technician
Do you have an ODB2 scanner (not just a code reader)? It would help to know what the values are for:
Note. A intake vacuum leak can make the MAF read low from the un-metered air. This will also show up in the LTFT's as positive number (adding fuel) at idle. Normally a vacuum leak will also show a decrease in LTFT's as the throttle is advanced. This is because the ratio of un-metered to metered air decreases as the throttle is opened.
It seems to me that as part of a new build the basic MAF functionality should be confirmed as a wiring problem could be involved.
On "trick" is to disconnect the MAF which will force the PCM into "open loop". If the motor starts and runs, this strongly points to a MAF related issue.
Is the fuel pressure regulator intake vacuum reference line connected and leak free? Have you confirmed that the fuel pressure is being referenced to the intake vacuum?
If you do not have an ODB2 scanner, here's some information on an affordable ($30) Windows based unit that is able to access operational PID's as well as graph multiple PID"s. Might make short work of your problem.
ForScan ODB2 scanner w ELM327 USB
https://www.stangnet.com/mustang-forums/resources/forscan-odb2-scanner-w-elm327-usb.57/
- MAF flow
- Long term fuel trim (LTFT) bank 1 and 2.
- PCM operating mode (open loop or closed loop)?
- Are the O2 sensors switching or stuck lean/rich?
Note. A intake vacuum leak can make the MAF read low from the un-metered air. This will also show up in the LTFT's as positive number (adding fuel) at idle. Normally a vacuum leak will also show a decrease in LTFT's as the throttle is advanced. This is because the ratio of un-metered to metered air decreases as the throttle is opened.
It seems to me that as part of a new build the basic MAF functionality should be confirmed as a wiring problem could be involved.
On "trick" is to disconnect the MAF which will force the PCM into "open loop". If the motor starts and runs, this strongly points to a MAF related issue.
Is the fuel pressure regulator intake vacuum reference line connected and leak free? Have you confirmed that the fuel pressure is being referenced to the intake vacuum?
If you do not have an ODB2 scanner, here's some information on an affordable ($30) Windows based unit that is able to access operational PID's as well as graph multiple PID"s. Might make short work of your problem.
ForScan ODB2 scanner w ELM327 USB
https://www.stangnet.com/mustang-forums/resources/forscan-odb2-scanner-w-elm327-usb.57/
Last edited:
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