2000 Ford F250 Lower Power with Knocking

Bernie Diagnostician New Mexico Posted   Latest  
Case Study
ATS - Automotive Test Solutions
Driveability
2000 Ford F-250 Super Duty Lariat 7.3L (F) 5-spd (S5-47)
Low Power
Knocking

Here is a case study I have just completed that gives a great tip when working on a diesel engine, this F 250 has low power with an engine knock.

diag​.​net/file/f6z1t6je6…

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Helpful
Interesting
Thanks
Chris Technical Support Specialist
New York
Chris
 

I have seen plenty of 6.0 injectors with leaking and aeration causing stalling issues. These were typically found with a balloon or a bubble test. Most often they were caused by low fuel pressure allowing the intensifier piston in the injector to beat itself up. Great demonstration for isolating that fault!

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Tony Owner/Technician
Missouri
Tony
 

Hi Bernie, thanks for this case study. I have a couple questions if I may. I should mention you were accidentally calling the CMP frequency waveform “crankshaft” for the duration of the your initial explanation of how it worked - just mentioning because it could complicate someone's initial view. You mentioned that the “indexing mark” after cylinder 3 fires is why the frequency waveform goes…

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Chris Technical Support Specialist
New York
Chris
 

The 7.3 only has a cam sensor and this is an International engine and things are a little different than your typical Ford Engine. CMP is typically used for cylinder identification in power balance. CKP is what is monitored for IDS power balance. If you have CMP faults the power balance will not work in IDS. As far as the waveforms I would have to refer to Bernie for those questions.

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Tony Owner/Technician
Missouri
Tony
 

Thanks, Chris. CMP might be capable of supplying data for power balance if it was a high resolution sensor like this one appears to be. Whether it would be accurate enough to do it well I couldn't say.

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Bernie Diagnostician
New Mexico
Bernie
 

Tony The Frequency plot uses the rising edges of the waveform. This indexing is different from cylinder 3 to cylinder 6. In order to properly calculate a shaft velocity changes there should be greater than 20 teeth per shaft rotation .

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Tony Owner/Technician
Missouri
Tony
 

Awesome, thanks Bernie. It looks like the 7.3 has 24 pulses minus the cylinder 3 identifier. Thanks for explaining the rising edge theory. I wonder if your scope has a falling edge option so you could see the #3 event if that was a concern.

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Bernie Diagnostician
New Mexico
Bernie
 

Tony The Escope frequency plot only looks at rising edges at this time. However if the trigger has more teeth on the wheel you can run it in the CKP program. This will automatic insert the missing teeth.

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Rusty Owner/Technician
Massachusetts
Rusty
 

Nicely done. Thats a pretty neat way of finding the offending hole when there aren’t any contribution codes. If there weren’t any, I’d be surprised given the steady miss at idle. As Chris pointed out, this is a pretty common fault with Sickos. They drop one hole and slowly progress to the other 4 on that bank. I built a secondary fuel filter cap for both the 7.3 and Sickos with a Schrader…

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