Do Tuners do this to 7.3L's?
Posting Guru
Joined: Sep 2006
Posts: 1,309
Likes: 2
From: Plainfield, IL
Iirc the star pattern appears because of the way a tuner changes the timing and adds fuel. I don't believe it harms anything though. I know that during the 6.0 crisis Ford would look for the star pattern as proof that a tuner was being used and would then deny warranty.
Post Fiend
Joined: Feb 2008
Posts: 10,977
Likes: 5
From: Lancaster, Pa.
So in a nutshell Greg, a chipped truck would have more of this scoring or about the same as stock, depending on fueling amounts?? This is a bad thing or is this normal?? Thanks, o yea, nice pics mechelement Jason.
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Cargo Master
Joined: Oct 2008
Posts: 3,330
Likes: 13
From: Eaton, CO
Ok, so it is scoring due to overfueling, which could be caused by:
I'm not sure if those are correct. Does this happen with 7.3L's running DP Tuners? Has anyone cracked one open to see? Is this bad for a diesel motor?
- poor injector timing caused by tuners ( note: stock tunes have been found off spec )
- poor injectors
- poor spray nozzle(s)
I'm not sure if those are correct. Does this happen with 7.3L's running DP Tuners? Has anyone cracked one open to see? Is this bad for a diesel motor?
Elder User
Joined: May 2008
Posts: 860
Likes: 2
From: Liberty Lake, WA
When the star pattern is happening the injection event is too soon or too late. The fuel is supposed to be dispensed inside the bowl, but if the bowl is not close enough to the injector tip when its told to fire, it can spray the top of the pistons like in the picture.
Look at this picture of my last motor. Look closely at hole #2 (closest to you) and you can see dark circles inside the piston bowl. This is where it should be.
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Post Fiend
Joined: Feb 2006
Posts: 11,892
Likes: 2
From: Middle Tennessee
Ok, so it is scoring due to overfueling, which could be caused by:
I'm not sure if those are correct. Does this happen with 7.3L's running DP Tuners? Has anyone cracked one open to see? Is this bad for a diesel motor?
- poor injector timing caused by tuners ( note: stock tunes have been found off spec )
- poor injectors
- poor spray nozzle(s)
I'm not sure if those are correct. Does this happen with 7.3L's running DP Tuners? Has anyone cracked one open to see? Is this bad for a diesel motor?
EDIT: don't read this as over fueling from my response, just not happening where it is supposed to sometimes.
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Hotshot
Joined: Jan 2008
Posts: 13,144
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From: Rochdale MA
From what I have read, yes, yes, and yes. It is not confined to any one tuner. Can happen on a stock truck with bad nozzles. Let's not finger point at tuners though it is easy to do because one could say my timing was off and therefore the SOI caused this. There is a lot more to SOI than just when it happens. Your ICP, type and health of injectors, EOT, cylinder pressure and on and on.
EDIT: don't read this as over fueling from my response, just not happening where it is supposed to sometimes.
EDIT: don't read this as over fueling from my response, just not happening where it is supposed to sometimes.
Super Moderator
Joined: May 2004
Posts: 29,380
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From: Central Coast of CA
Stewart
Post Fiend
Joined: Jun 2004
Posts: 9,293
Likes: 10
From: Parker, CO
Ok, so it is scoring due to overfueling, which could be caused by:
I'm not sure if those are correct. Does this happen with 7.3L's running DP Tuners? Has anyone cracked one open to see? Is this bad for a diesel motor?
- poor injector timing caused by tuners ( note: stock tunes have been found off spec )
- poor injectors
- poor spray nozzle(s)
I'm not sure if those are correct. Does this happen with 7.3L's running DP Tuners? Has anyone cracked one open to see? Is this bad for a diesel motor?
I have a steady diet of bone stock work/oil field trucks come through my shop. All brands, all years. I see the star pattern quite often on these trucks when I tear down a motor. In fact, I have a 05 Cummins in the shop right now that is torn down. Two of the pistons have the star pattern on them, one really bad. One can only assume that the root cause is the injector. If not, all of the cylinders would have the pattern.
So, just to add some more confusion to the discussion, it is my thought that lots of idling and running the trucks when the cylinders aren't fully warmed up are the root cause of most of the star patterns. Throw in some injector nozzles that get waddled out by water or debris or perhaps were out of spec when they were produced, you have the makings of combustion event that is happening outside of the combustion bowl.
I have never seen the star pattern on extremely high mile motors that I have torn down that were just run hard their whole life with minimal idling. On the other hand, I have torn down a few 6.0's and 5.9's that have run off the shelf programmers most of their life that have the star pattern. I could contribute that to a fueling/timing issue.
It's too hard to throw a blanket statement on this issue.
So, just to add some more confusion to the discussion, it is my thought that lots of idling and running the trucks when the cylinders aren't fully warmed up are the root cause of most of the star patterns. Throw in some injector nozzles that get waddled out by water or debris or perhaps were out of spec when they were produced, you have the makings of combustion event that is happening outside of the combustion bowl.
I have never seen the star pattern on extremely high mile motors that I have torn down that were just run hard their whole life with minimal idling. On the other hand, I have torn down a few 6.0's and 5.9's that have run off the shelf programmers most of their life that have the star pattern. I could contribute that to a fueling/timing issue.
It's too hard to throw a blanket statement on this issue.
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Cargo Master
Joined: Oct 2008
Posts: 3,330
Likes: 13
From: Eaton, CO
It just seems like everyone comes here and immediately wants to throw a tuner on their 7.3. Then all the folks who have tuners jump in and encourage.
I use my truck for work and have read nothing, but good things about the DP Tuner on this site and I'm sure it's great... The claims of better fuel economy, efficiency, more power, torque, etc. Hell, that makes me want to buy one after reading all that good stuff, call it a business expense and write it off.
Well, the reality of it is, it's best to go over that motor with a fine toothed comb before slapping a tuner in it. Even then, it could be hit or miss.
I find it interesting that person mentions not finding scoring on stock, high mileage motors which were used daily. My wife told me the day we bought this truck, "We should keep the motor in stock form, all those folks who throw tuners in there tear them up. This truck needs to last." There's a guy shoeing here who has more than 450k miles on his OBS 7.3L. IIRC, he installed a different turbo, exhaust, downpipes and intake. It doesn't have a tuner and I couldn't keep up with him through the hills.
I use my truck for work and have read nothing, but good things about the DP Tuner on this site and I'm sure it's great... The claims of better fuel economy, efficiency, more power, torque, etc. Hell, that makes me want to buy one after reading all that good stuff, call it a business expense and write it off.
Well, the reality of it is, it's best to go over that motor with a fine toothed comb before slapping a tuner in it. Even then, it could be hit or miss.
I find it interesting that person mentions not finding scoring on stock, high mileage motors which were used daily. My wife told me the day we bought this truck, "We should keep the motor in stock form, all those folks who throw tuners in there tear them up. This truck needs to last." There's a guy shoeing here who has more than 450k miles on his OBS 7.3L. IIRC, he installed a different turbo, exhaust, downpipes and intake. It doesn't have a tuner and I couldn't keep up with him through the hills.
Super Moderator
Joined: May 2004
Posts: 29,380
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From: Central Coast of CA
Well, the reality of it is, it's best to go over that motor with a fine toothed comb before slapping a tuner in it. Even then, it could be hit or miss.
Then why bother suggesting it?
My wife told me the day we bought this truck, "We should keep the motor in stock form, all those folks who throw tuners in there tear them up.
Stewart
Post Fiend
Joined: Feb 2008
Posts: 10,977
Likes: 5
From: Lancaster, Pa.
No its not an over fueling issue. Its is caused by the timing of the injection event.
When the star pattern is happening the injection event is too soon or too late. The fuel is supposed to be dispensed inside the bowl, but if the bowl is not close enough to the injector tip when its told to fire, it can spray the top of the pistons like in the picture.
Look at this picture of my last motor. Look closely at hole #2 (closest to you) and you can see dark circles inside the piston bowl. This is where it should be.
When the star pattern is happening the injection event is too soon or too late. The fuel is supposed to be dispensed inside the bowl, but if the bowl is not close enough to the injector tip when its told to fire, it can spray the top of the pistons like in the picture.
Look at this picture of my last motor. Look closely at hole #2 (closest to you) and you can see dark circles inside the piston bowl. This is where it should be.
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Cargo Master
Joined: Oct 2008
Posts: 3,330
Likes: 13
From: Eaton, CO
LOL.
I'd assume if the motor has been gone through very carefully and everything was in excellent working order, you'd stand a better chance of no scoring w/ a good tuner. That's strictly an engineering hypothesis. Then look what Tenn01PSD350 states. Seems like it could happen regardless of what tuner and what shape your motor is in.
Seems like a reasonable statement from someone with limited experience with diesel motors based from their personal observations. She doesn't work on diesels or diagnose their issues. Hey, she knew enough to stay away from the 6.0. 
I'd assume if the motor has been gone through very carefully and everything was in excellent working order, you'd stand a better chance of no scoring w/ a good tuner. That's strictly an engineering hypothesis. Then look what Tenn01PSD350 states. Seems like it could happen regardless of what tuner and what shape your motor is in.
I would agree with someone who believes that using a custom tune to unleash the power left on the table by Ford's stock programming will probably shorten the overall lifespan of the engine, but to make a blanket, all-inclusive statement that all of us are tearing them up is a bit over the top.
Stewart
Stewart