Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
CRANK NO START AFTER ENGINE REPLACEMENT. PCM READS 0 VOLTS FROM MAF SENSOR
THE VEHICLE IS A 2012 FORD EXPEDITION 5.4L. VEHICLE RAN BEFORE I REMOVED, REBUILT AND INSTALLED ENGINE DUE TO DAMAGED CAMS AND ROLLER ROCKERS. ENGINE HAS NO ISSUES CRANKING. IT WILL KINDA START THEN DIE. WHEN MAF IS UNPLUGGED, VEHICLE WILL START INITIALLY WITH HIGH IDLE, BUT WILL SOON CHUG AND 0ULTIMATELY END UP DYING IF NOT PRESSING ON TIHE THROTTLE, I HAVE FORSCAN SO I CAN VIEW SCAN DATA. ALL NUMBERS APPEAR TO BE FINE EXCEPT THE MAF (V) READING. IT IS CONSTANTY 0.0V, EVEN 0.0000 VOLTS WHEN DECIMAL IS MOVED, IT IS A 4 WIRE MAF SENSOR INCLUDING 'MAF,MAFRTN,PCM SWITCHED POWER,IAT' AS THE INCLUDED WIRES. THE MAF CIRCUIT IS 5V, EXCEPT WHEN PLUGGED INTO SENSOR IT BECOMES 3.4V, THE MAFRTN MAINTAINS .02--.03mV THE PCM POWER IS 12V. I HAVE TESTED WIRES IN CIRCUIT AND FOUND NO ISSUES. WITH THEM. STILL 0 VOLTS ON SCANTOOL, I HAVE BYPASSED MAF/MAFRTN WIRES IN HARNESS AND RAN TWO SEPERATE WIRES TO PCM, VOLTAGE STILL READS 0 VOLTS. REPLACED MAF SENSOR AND STILL 0 VOLTS. MAF WILL READ g's AND FREQUENCY BUT NOT VOLTS. COULD THIS BE THE REASON WHY ENGINE IS NOT STARTING? DTCS ARE USUALLY P0100. BUT LATELY, P0390 AND P0394 ALSO HAVE BEEN APPEARING. I REMOVED TIMING COVER TO VERIFY TIMING MARKS AND EVERYTHING WAS AS IT SHOULD BE. COMPUTER ALSO SHOWS THAT ENGINE IS IN TIME. WHAT AM I MISSING? IS IT AN ISSIE THAT VOLTAGE GOES FROM 5V TO 3.5V WHEN PLUGGED IN? IWHY WONT THE COMPUTER READ THE VOLTAGE? IS IT RELATED TO WHY ENGINE WONT START? TRYING TO GET VEHICLE STARTED BECAUSE FRIEND IS GIVING ME HIS 2001 7.3L IN EXCHANGE FOR REPAIRING HIS EXPEDITION.
Try not to reply all in CAPS as it makes it appear as if you're yelling & some people will get annoyed by it.
Sounds as if something isn't connected as the 0 volts you're referencing.
I'm not a Ford guy but I'm sure once the members get on later this morning or evening you'll have plenty to go check
I believe one of the Mods Tyler does Ford quite a bit so maybe check with him if he doesn't reply first
IF you've got a P0390 that's a camshaft position sensor code so I'd check teeth, sensor, etc for Damage , wire not plugged all the way in, check for bent pins on any and all connectors you removed and refastened before, during & after the repair as it only takes a connector that has a loose fitment issue to throw things out of whack
Check & see if there's any related fuses as well that could be giving you issues.
Ya the CAPS lock didnt dawn on me till after. i will have to check out the forum though. I believe ive done all that you mentioned. But these have cam phasers, i checked the straightness on them and they seemed to be correct. but I just may have to go back for another look. I will have to snap some pics of everything when i go out to the garage
A frequency output MAF isn't gonna have a voltage PID. Sounds like Forscan is displaying a PID the vehicle doesn't support. The 3.4V you're measuring plugged in is likely the DMM averaging a 0-5V DC square wave.
Troubleshoot the timing codes. If everything appears to be OK check you have the correct parts installed. And if any components are bank specific make sure they're on the correct bank.
