P1668 and Injector #8 fails contribution test, help!

[woodsman]

So the truck has been getting crappy mileage, running hot (just going up a hill with TC locked in 4th at 55-60 mpg will easily get over 1000 degrees in the downpipe) and getting 12-13mpg where it used to get 17-19. Ran some tests last night and pulled a P1668 right off the bat, then #8 failed a CCT. After that, all injectors passed a buzz test. Started to follow the troubleshooting directions from All Data, found under 5 ohms as directed in FJ2, but then it said to go to FJ3 which requires a Breakout Box which I'm unfamiliar with? Any ideas? Truck is in my sig. Cylinder 8 also had 360 LB's of compression when the injector, icp sensor and turbo were replaced 2500 miles ago. Somebody mentioned checking for a boost leak previously, I pressure tested the intake side of things and it held pressure perfectly. Have not tested exhaust side for leaks yet.:fordoval:

 

[JLDickmon]

does it run like a gasser with a bad plug wire?

 

[golfer]

CCT tests do not flag "injectors" as being bad....

here's an excerpt from this link:

http://www.swampsdiesel.com/files/7.3LInjectorDiagnostic.pdf

CCT test:
this test compares the RELATIVE BALANCE between the output of (not just the injs!) but
everything that contributes to the power output of that cylinder...which includes quite a lot.. from
that cylinders compression (piston ring sealing), the intake & exhaust valve sealing, valve lift,
injector output, etc..we've even seen bad torque converters and flywheels cause enough engine
vibration to cause various cylinder balance faults..so, while a scan tool can aid in the
detection/direction of a problem... experience can & will outweigh a scan tool 9 out of 10
times..."no codes" doesn't mean everything is "OK"...and conversely...just because you HAVE a
code...doesn't mean that there is a problem...or it has anything at all to do with a specific problem
or issue.
so...a truck could have 8 weak injectors...that show up FINE on these tests...or 8 GOOD injectors
that could fail CCT in a worn out engine...balance is balance...so even if you DID have
something show up on a CCTest...it doesn't mean it's BAD...hell we've seen guys replace the
same inj, multiple times...leaving the other 7 w/ 200k+ miles...and call back saying that they still
have the same code(s)...in these types of cases...a STRONG injector will show out of balance
against the 7 old/weak injs...
More rare issues, such as aerated engine oil...or aerated fuel can also cause
goofy/poor/inconsistent running issues..that new injectors can't fix...or may only fix for a short
time...
the last thing we like to do is have someone purchase injs for a truck/engine that needed
injectors...but later finds out that the injectors weren't the only problem.
Compression is king...meaning....that if the compression is good...then the engine can be fixed,
and is worth investing time/money in getting it to run properly...but if compression is poor or
mediocre...no amount of injectors, sensors, fuel system/HPOil system improvements are going to
make it 100% right...it may only make the situation/engine run "better"...

 

[Dieselboy.]

Grey CPS ?

 

[woodsman]

Grey CPS ?

Yes, looking for a oldschool black one now. Let me know if anybody has a line on one please. I'll be getting a compression test done ASAP.

 

[woodsman]

So I replaced the grey cps with a blue one, started a little better but still throws a number 8 cct fault. Ideas?

 

[ToMang07]

So I replaced the grey cps with a blue one, started a little better but still throws a number 8 cct fault. Ideas?

The blue and the grey CPS's can cause a #3 or a #8 CCT "fail" code. If that's the only issue, it's not worth worrying about. Mine would throw one or both, then I got a black CPS...and it stopped. They are almost impossible to find nowadays tho.

 

[Project20v]

My truck almost always failed #8 on CCT. Nothing was ever wrong, I just let it be. I thought maybe it had to do with the firing order because it ends on 6 and 8 which are the only 2 that fire right next door to eachother???? I have 2 new blacks that I no longer need since I junked the 7.3..

 

[ToMang07]

My truck almost always failed #8 on CCT. Nothing was ever wrong, I just let it be. I thought maybe it had to do with the firing order because it ends on 6 and 8 which are the only 2 that fire right next door to eachother???? I have 2 new blacks that I no longer need since I junked the 7.3..

you sir have a PM, lol

 

[golfer]

My truck almost always failed #8 on CCT. Nothing was ever wrong, I just let it be. I thought maybe it had to do with the firing order because it ends on 6 and 8 which are the only 2 that fire right next door to eachother???? I have 2 new blacks that I no longer need since I junked the 7.3..

yep...even worse with dead head fuel system annnnnd split shot injectors...(splits actually "inject" a very small amount of fuel back into the fuel RAIL in the head...but at full injection pressure, which causes quite a disturbance to the 'quality' of fuel that #8 injector gets.)

if there isn't a true misfire that can be detected while driving...then balance codes for cyls 8, 1 & 8 or 3 & 8 are safe to ignore with no other symptoms which might be cause for further diagnostics..

 

[TARM]

Dave,

I figure you guys must have done a good bit of diagnosis into the issue with the newer CPS. What causes the grey CPS to show these faults? Of the various things the CCT checks what is it that the grey cps is effecting? I know a number of people have pulled them apart to compare. IIRC the magnets are smaller in the new ones with the old black having the largest one?

 

[ToMang07]

Dave,

I figure you guys must have done a good bit of diagnosis into the issue with the newer CPS. What causes the grey CPS to show these faults? Of the various things the CCT checks what is it that the grey cps is effecting? I know a number of people have pulled them apart to compare. IIRC the magnets are smaller in the new ones with the old black having the largest one?

https://sites.google.com/site/woodnthings8/2002-f-350-superduty/cam-position-sensor-information

 

[TARM]

Thanks for the link but I did already read that back when it was first done. What I am interested in is what parts of the test are effected. Dave(Golfer) has broken down a number of times what all is tested in the CCT. What I am interested in is there a way to see the results of each one of those tests and know what parts are being effected by the CPS. It obvious does effect the actually running performance of the a engine so its not just an effect of on the test itself. I lost 1mpg and the idle changed. I am wondering if its not giving an accurate signal of the camshaft position thus effecting the SOI of the injector and thus effecting both perf and idle quality.

One of the major dif I can see if the magnet strength. I wonder if you could take one apart and cut a stronger magnet to use in place of the one.

I still can not understand why they decided to go with a weak magnet and especially not change it when they see how many of these are causing failures of the test spec they themselves created.

Reason I was asking Dave is they seem to have dove the deepest into the electronics of the 7.3. Not to mention they have a full dyno with CP testing so they can see things like Start of combustion etc. Swapping CPS and then comparing the differences.

 

[TARM]

Another question:\

Why is it even with a black CPS that 3 and 8 seem to always be higher. Yes they fall into the normal range but what is it about 3 and 8 that make them higher? Is this only with deadhead fuel and split shot injectors or does this trend continue with single shot and RR fuel setups? I would check but I am waiting on my IH water pump to arrive to button everything up.