Lethalthreat7.3
New member
I posted this under the 6.7 while addressing an issue Lincollocker was/is having and thought maybe i should paste it here in the 7.3 section.
Lincoln, my truck would do this type of thing intermittently as well. Would sound like a cylinder or two was hammering and blowby would increase.
I did A LOT of research. I've been working on 7.3's ever since Ford built them after the 6.9 and was working on Caterpillar equipment when they were designing the 110vac/IDM injection system which was first used in 1992.
Anyway, Ford engineers have been working on the "Phantom" glitch for over ten years and as everyone knows the CAMP sensor has been redesigned/changed 4 or 5 times.
I came across a writeup by WoodnThings(psn i thk) where he stated that the wiper motor was causing an issue according to Ford engineers with a posted "memo", not a TSB(that would mean another recall and $$)
For the life of me I could not figure out how/why a motor that requires 12v to operate would cause an issue as it is either on or off with a timer for intermittent operation on low.
He isolated the CAMP sensor with ferrite chokes. Didn't solve it. He shielded the wiper motor as well then claimed it idled like a 6.0 or better(as you know they are smoother/quieter than7.3's).
I have an extensive electrical diagnostic's background in both the automotive and HVAC fields(Ford Electrical Systems, Driveability Diagnostic Cert...NCEER Instructor Cert) so I decided to try and address this issue based on what I know and have experienced in 30+yrs.
The CAMP sensor uses a magnetic pickup and cam sensor ring to generate a AC sine wave, the same as the vss. The AC sine wave is amplified(Darlington Amplifier) and converted to a DC sine(Schimdt Trigger).
This signal generates a DC voltage between 0.3 and 2.7vdc back to the pcm. There is a different gap before #1 and then before #4 to signal the pcm when to fire the IDM/inj's accordingly.
The injectors are AC driven. The AC sine wave and DC sine waves are completely different. AC is a "rolling" sine wave that in the US is 60hz @120vac. It would look like a hill that goes 30 cycles positive and 30 cycles negative.
DC sine wave is square going from 0v to 5v(this case 0.3-2.7vdc).
The first rule in automation controls is to NEVER run AC wires and DC wires parallel to each other as the AC sine wave will(trust me on this), intermittently cause "phantom" voltage and control issues. I have diagnosed and repaired multi-million dollar systems that have taken weeks to hunt down simply because of control wiring interference.
Anyway. I installed shunts on the CAMP sensor to absorb any EMI or RFI noise. Started it and was stunned how well it ran but..... After it had run for about 10/15mins it started to get a slight miss again sooo.... I scanned it but nothing. I decided to test my wipers. Good on low, good on high but on intermittent the truck stumbled for just a split second.
I rescanned and got high limit codes for the ICP, EOT, EBP and one other(forgot it). Anyway i decided to research this on a wiring diagram and found that every sensor happened to be on the same vref. My thought was some type of interference and it seemed like it had just built up a "charge" similar to static electricity as it didn't do it for the first 15mins.
I then tested my wiper motor which worked but I did have a code for intermittent wiper circuit and park circuit. It only tested at 1.7ohms but worked.(btw uses a cam gear for operation where the newer motors use a magnetic pickup to signal the pcm as to the wiper position).
New motor tested at 39ohms. While I was in there i installed shunts here as well. When testing the new motor it didn't seem to work right in intermittent.
I pulled the multifunction switch. My truck being an e99(feb98), uses a '97 mfs and I couldn't find one so I disassembled mine. The corrosion blew me away. After some serious "remanufacturing" I reinstalled it.
I nearly shat myself when I started it. If I didn't know it was a 7.3 I would have laid a serious bet on it being a different diesel motor. My buddy was blown away.
Power, holy crap. When its hitting correctly, well I always thought it ran really good. Now it is outstanding!
I feel it is an EM interference issue but have not scoped the sine wave from the CAMP sensor to see if it becomes erratic. I had full intentions on building a separate shielded injector harness to completely separate all the DC sensors from the AC driven injectors, and may still do it but at this time the truck runs so smooth(better cold at 45* than before warmed up) that I see no sense at this time doing that.
However, if it gets just one hiccup i'll have it built in a day.
FYI, before I went down this path I had put a new BWD CAMP sensor in. Ran good for about an hour then started "rattling" just like Lincolnlocker's did. Testing the circuit A to B the new one was 31m ohms. Old blackC91 sensor read 51k ohms. Woodnthings stated his good one was 53k. (Reading left to right, magnet down. A=ground, B=vref, C=sig ret)
I ordered two different sensors from NAPA. Two were the grey big magnet ones the other two were the new black ones. ALL FOUR TESTED DIFFERENTLY. One was 14m, one 18m, one at 24m and the other in excess of 35m ohms. So if they all test differently, which one is correct?
Very, very lengthy. I apologize but I had to post this info to hopefully help someone out. I have pictures if anyone is interested as well as a couple of video's with it running erratically and smoking before as well as when I started it after all this work.
Lincoln, my truck would do this type of thing intermittently as well. Would sound like a cylinder or two was hammering and blowby would increase.
I did A LOT of research. I've been working on 7.3's ever since Ford built them after the 6.9 and was working on Caterpillar equipment when they were designing the 110vac/IDM injection system which was first used in 1992.
Anyway, Ford engineers have been working on the "Phantom" glitch for over ten years and as everyone knows the CAMP sensor has been redesigned/changed 4 or 5 times.
I came across a writeup by WoodnThings(psn i thk) where he stated that the wiper motor was causing an issue according to Ford engineers with a posted "memo", not a TSB(that would mean another recall and $$)
For the life of me I could not figure out how/why a motor that requires 12v to operate would cause an issue as it is either on or off with a timer for intermittent operation on low.
He isolated the CAMP sensor with ferrite chokes. Didn't solve it. He shielded the wiper motor as well then claimed it idled like a 6.0 or better(as you know they are smoother/quieter than7.3's).
I have an extensive electrical diagnostic's background in both the automotive and HVAC fields(Ford Electrical Systems, Driveability Diagnostic Cert...NCEER Instructor Cert) so I decided to try and address this issue based on what I know and have experienced in 30+yrs.
The CAMP sensor uses a magnetic pickup and cam sensor ring to generate a AC sine wave, the same as the vss. The AC sine wave is amplified(Darlington Amplifier) and converted to a DC sine(Schimdt Trigger).
This signal generates a DC voltage between 0.3 and 2.7vdc back to the pcm. There is a different gap before #1 and then before #4 to signal the pcm when to fire the IDM/inj's accordingly.
The injectors are AC driven. The AC sine wave and DC sine waves are completely different. AC is a "rolling" sine wave that in the US is 60hz @120vac. It would look like a hill that goes 30 cycles positive and 30 cycles negative.
DC sine wave is square going from 0v to 5v(this case 0.3-2.7vdc).
The first rule in automation controls is to NEVER run AC wires and DC wires parallel to each other as the AC sine wave will(trust me on this), intermittently cause "phantom" voltage and control issues. I have diagnosed and repaired multi-million dollar systems that have taken weeks to hunt down simply because of control wiring interference.
Anyway. I installed shunts on the CAMP sensor to absorb any EMI or RFI noise. Started it and was stunned how well it ran but..... After it had run for about 10/15mins it started to get a slight miss again sooo.... I scanned it but nothing. I decided to test my wipers. Good on low, good on high but on intermittent the truck stumbled for just a split second.
I rescanned and got high limit codes for the ICP, EOT, EBP and one other(forgot it). Anyway i decided to research this on a wiring diagram and found that every sensor happened to be on the same vref. My thought was some type of interference and it seemed like it had just built up a "charge" similar to static electricity as it didn't do it for the first 15mins.
I then tested my wiper motor which worked but I did have a code for intermittent wiper circuit and park circuit. It only tested at 1.7ohms but worked.(btw uses a cam gear for operation where the newer motors use a magnetic pickup to signal the pcm as to the wiper position).
New motor tested at 39ohms. While I was in there i installed shunts here as well. When testing the new motor it didn't seem to work right in intermittent.
I pulled the multifunction switch. My truck being an e99(feb98), uses a '97 mfs and I couldn't find one so I disassembled mine. The corrosion blew me away. After some serious "remanufacturing" I reinstalled it.
I nearly shat myself when I started it. If I didn't know it was a 7.3 I would have laid a serious bet on it being a different diesel motor. My buddy was blown away.
Power, holy crap. When its hitting correctly, well I always thought it ran really good. Now it is outstanding!
I feel it is an EM interference issue but have not scoped the sine wave from the CAMP sensor to see if it becomes erratic. I had full intentions on building a separate shielded injector harness to completely separate all the DC sensors from the AC driven injectors, and may still do it but at this time the truck runs so smooth(better cold at 45* than before warmed up) that I see no sense at this time doing that.
However, if it gets just one hiccup i'll have it built in a day.
FYI, before I went down this path I had put a new BWD CAMP sensor in. Ran good for about an hour then started "rattling" just like Lincolnlocker's did. Testing the circuit A to B the new one was 31m ohms. Old blackC91 sensor read 51k ohms. Woodnthings stated his good one was 53k. (Reading left to right, magnet down. A=ground, B=vref, C=sig ret)
I ordered two different sensors from NAPA. Two were the grey big magnet ones the other two were the new black ones. ALL FOUR TESTED DIFFERENTLY. One was 14m, one 18m, one at 24m and the other in excess of 35m ohms. So if they all test differently, which one is correct?
Very, very lengthy. I apologize but I had to post this info to hopefully help someone out. I have pictures if anyone is interested as well as a couple of video's with it running erratically and smoking before as well as when I started it after all this work.
opcorn:
