When I run the test, cylinder 2 and 8 fail. When in P or N the the truck shakes as you slowly take the rpms up to 2k or so then its fine. But when your going down the road no matter what rpm the truck is smooth as glass. Should I not worry about it?
7.3 contribution test faults
- Thread starter onebad7.3
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PSDEng
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Have you changed a CPS lately? A bad one is sometimes known to cause the balance faults. If you haven't you might want to go ahead and try, then if that doesn't fix it we can go from there.
Justin@DP-Tuner
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I would say it is an oil related issue if it only does it when hot. Can you monitor ICP and IPR?
PSDEng
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This is directly from Swamp's website:
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"...
What I'm getting at is....this might be completely unrelated to injectors and could be "something else" that contributes to the balance of the motor.
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"...
What I'm getting at is....this might be completely unrelated to injectors and could be "something else" that contributes to the balance of the motor.
Justin@DP-Tuner
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Have you pulled the VC's and watched the oil coming out of the injectors?
This I haven't done, but I wouldn't think I would have to because Swamps redid the injectors when I bought them. Then after 3,000 miles or so I still had the problem so I pulled the injectors out and sent them to Nate and told him what the truck was doing. He said what ever is causing the problem isn't the injectors, they are perfect.
BDP Tuner
New member
Have you checked Fuel Pressure or your ICP?
PSDEng
New member
Have you made sure that all the injectors are plugged in properly? Also, when you installed the injectors how hard did you tap on the solenoids? There could be two possibilites: 1) You didn't tap hard enough and they're not seated correctly, which may or may not be contributing to your problems or 2) You hit them too hard and damaged the solenoid, which very well may be causing your problem.
I checked for codes a few times, nothing. Around 6,000 miles on the injectors. I don't know for sure how long I've had the symptoms, because it only does it when your in P or N and slowly take the rpms up. Going down the road it runs perfect. I just noticed it one day probably a year ago, but since it doesn't affect the driveability of the truck I didn't pay any attention to it. But I want to get it fixed before this winter
Yes all injectors are plugged in properly, I had one that came unplugged when I put the vc on, but noticed it right away and took the vc off and plugged it back in. How much are new solenoids?
Theres a lot I don't understand about how these injectors work, but if the solenoids are damaged wouldn't Nate have caught that when he tested the injectors? Because the truck was running like this, then I pulled the injectors, sent them to him and had them checked out to rule out the injectors.
If two solenoids are damaged why does the truck only have a miss when you slowly take the rpms up when your in P or N and not when your driving down the road?
Why is it when I put different cps's in the number of cylinder that fails changes. Lets say 2 solenoids are bad, wouldn't those two always fail no matter what cps was in the truck?
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PSDEng
New member
I'm sure Nate would've caught anything wrong with the injectors when he tested them, but if you want to be completely sure that they're all electrically ok, run a buzz test on them and pay attention to how they sound.
Here's a question though, if the truck runs fine, why be so worried about a code that isn't effecting performance?
As for the other questions in your previous post, I can't honestly answer them. I've had an experience with chasing balance faults around, but the truck ran ok. If you read what I posted from Swamp's website, those codes can be a result of a number of reasons.
Here's a question though, if the truck runs fine, why be so worried about a code that isn't effecting performance?
As for the other questions in your previous post, I can't honestly answer them. I've had an experience with chasing balance faults around, but the truck ran ok. If you read what I posted from Swamp's website, those codes can be a result of a number of reasons.
Yes I read what you posted from swamps site, very helpful!
I'm not worried about the codes, just wondered why I have them.
Thanks to everyone for their info! Just going to run the truck the way it is.
If I start having problems, I'll be back
