I am not saying I think injectors break cranks. I'm saying it has been said that injectors break cranks, and I'm just trying to come up with ways that an injector might break a crank. I did not ever say that the injectors in Jay's truck are what caused his failure. I also didn't say the timing would change. The beginning and end of the injection cycle should not change at all. It would just be like one (or more) injector is significantly larger than the others. I don't know for sure what that would do to the engine, but I can see how it might be possible that having 7 injection pulses the same size and one much larger would put a lot of stress on the crank. I imagine it being kind of like an impact. When you are turning the bolt with an impact it is all turning in the same direction, but when the hammer hits the anvil it creates pressure spikes. I don't know for sure if what I'm saying is anywhere near correct, but I imagine the higher flowing injector being like the hammer hitting the anvil.
injectors = broken crank ?
- Thread starter BIG DIPPER
- Start date
I think you are referring to the tips only and big dipper is referring to the injector bodies.
IF you can't notice the engine running rough due to injector balance being out, then I doubt that there would be enough of an out of balance issue from the injector to make a crank fail, unless it ran for a long time like that, or the Harmonic Balancer was shot but by then you would likely have many other problems surfacing as well.
If we are talking harmonics let's talk a bone stock motor. People always jump to the injectors because that's what they read on the Internet. A bone stock motor will be so out of balance it'd shock those that put their hands on keyboards instead of hard parts.
What makes you think that? I'm talking about the flow of fuel coming out of an injector when it is installed in an engine being a significant amount off from another injector installed in the same engine.I think you are referring to the tips only and big dipper is referring to the injector bodies.
I'm not really sure how noticeable something like that would be. I know when I killed a piston in my engine, I didn't notice it running rough until I got stopped, but I guarantee that one cylinder was doing a LOT less work than the other 7. Not sure how that compares to one cylinder creating more power though.
That's when you would notice it Josh is at idle unless you have a really keen ear and are really in tune with your engine and how it runs. It would even be more noticeable when in gear at idle.
I notice it more than most do but that's because I work around engines for a living and after awhile, I start to notice stuff like that. I'm not saying I'm special, I just have acquired more of an ear for this sort of thing.
I notice it more than most do but that's because I work around engines for a living and after awhile, I start to notice stuff like that. I'm not saying I'm special, I just have acquired more of an ear for this sort of thing.
Unless you are running extremely high rail pressure at idle, I don't think mismatched injectors would be very bad at idle. Besides that, the balance rates should smooth it out unless it was out far enough that they couldn't make up for it. In that case, it should throw misfire codes.
Exactly. Unless they were way out you probably wouldn't notice them. And by way out, I mean like 15-20% or more, not 2-3%. Which, like was previously said, would be cleaned up by the ecm until it throws a code.
So is it safe to say you think the ECM only balances at idle and that there is no multiplying factor used in the upper RPM range based off of the balance rate that it used during idle? Also, other than the crank not being able to handle that other "hammer" hit....is it the crank is just too weak or would being incosistent be the killer? What if it was the other way around and you had 7 on par and 1 that was light instead of heavy?
Not sure I do either, but I do believe there is plenty more going on in the ECM that we are able to see.
NO I am not saying balanced injectors as opposed to nozzles or comparing anything of the like. The original quote was that a crank failed and the poster basically said that a baanced set of injectors would deter this......long story short. I would like to hear from him though.....
One that was light could still be found with a balance test. And it would also cause a missfire code if the engine could not manage it. I don't believe there is any more of a correction factor at idle then there is at say 2000 rpm because the load changes so much quicker as does everything else. That's why balance tests are reccomended to be done at idle in park because it is as controlled of a test we can do. Also, this why power contribution tests are done at the higher rpm's to measure cylinder performance while monitoring injector flow. Done with the tech 2 of course.
The only thing I can see changing at higher rpm's is the range that is allowable for injector balance at higher rpm's before the ecm throws a missfire code, but I can't say for sure as I don't believe this range is something we can see - yet.......
The only thing I can see changing at higher rpm's is the range that is allowable for injector balance at higher rpm's before the ecm throws a missfire code, but I can't say for sure as I don't believe this range is something we can see - yet.......
I think the argument is it may be only 2-3% at 4000 psi with an idle quantity fuel pulse, say 500 uS, but at 26k psi and 2800 uS it may be more along the lines of 30%.
I really don't know how accurate anything I'm saying is. I'm kind of playing devil's advocate to see what kind of ideas and theories we can come up with on this.
When I had my bent rod problem, I never threw a misfire code except at idle. When I blew a hole in my piston, it never threw a misfire code, but it didn't idle much at all. I'm not sure how long it needs to see the misfire condition before it throws the code. I'm assuming it throws the code based off of balance rates, and as mentioned above, balance rates zero out when you are driving.
I see. This is where the power contribution tests and injector tests with the tech 2 would make these problems show up.
Basically, the way I understand it, is the tech 2 commands a certain rpm and rail pressure and the tech monitors injector flow rates to determine if the injector is good or bad.
They can also see how much % of the load each cyl is supporting across the board if I'm not mistaken and that is the power contribution.
I've personally never worked with a tech 2 but this is how it was explained to me by a GM tech when he was diagnosing a diminishing rail pressure issue I had!
chalk it up to things just break.often times what makes one part in a certain truck isnt the coffin nail of the same part breakage in another truck.injects with the high pressures they see can go to crap in a short amount of time,however i dont see them breaking a crank unless it open so bad it hydrolocked and then i would think the rod would bend first.is the motor apart yet?what other parts show wear until this info is given out the rest is speculation at best.
last topic prolly wrong place and may tick a few peoplke off,but on a properly balanced engine set up an aftermarket dampner isnt needed...
last topic prolly wrong place and may tick a few peoplke off,but on a properly balanced engine set up an aftermarket dampner isnt needed...
GMC_2002_Dmax
The Still Master
I am going to weigh in here since I have tuned a ton of trucks with all different injectors from different shops.
At Merchants a few years ago Jay and Eric had very similar motor builds, both trucks were tuned by me and the only difference was the injectors, Jay's truck was way down on power compared to Eric's, at the time I was sure the injectors were crap.
Fast forward a few years, Jay's truck in it's current set-up IMHO was in need of a much bigger set of injectors because of the amount of air he has and power he is making vs the pulse width needed to get him into the low 10's or even 9's as that is the goal.
I believe that as long as the injectors suit the build and are within a few % of flow especially at WOT then you will be fine.
What I disagree on is when they are not matched very well you may have different cylinder pressures but the constant load on the crank per cylinder should be close to the same otherwise I believe that by applying different loads to different crank journals at high rpms, making big power will cause the harmonics to go off even with a balanced assembly leading to catastrophic failure.
Think of it as having a tire that is just a little out of balance, at low speed you may not notice it but at high speeds it shakes the truck.
I am not taking sides here either, I have tuned trucks with Socal, Big Dipper, Extrude Honed, II, Burkhardt, MA etc.
Some run better than others, some won't run worth a shit.
At Merchants a few years ago Jay and Eric had very similar motor builds, both trucks were tuned by me and the only difference was the injectors, Jay's truck was way down on power compared to Eric's, at the time I was sure the injectors were crap.
Fast forward a few years, Jay's truck in it's current set-up IMHO was in need of a much bigger set of injectors because of the amount of air he has and power he is making vs the pulse width needed to get him into the low 10's or even 9's as that is the goal.
I believe that as long as the injectors suit the build and are within a few % of flow especially at WOT then you will be fine.
What I disagree on is when they are not matched very well you may have different cylinder pressures but the constant load on the crank per cylinder should be close to the same otherwise I believe that by applying different loads to different crank journals at high rpms, making big power will cause the harmonics to go off even with a balanced assembly leading to catastrophic failure.
Think of it as having a tire that is just a little out of balance, at low speed you may not notice it but at high speeds it shakes the truck.
I am not taking sides here either, I have tuned trucks with Socal, Big Dipper, Extrude Honed, II, Burkhardt, MA etc.
Some run better than others, some won't run worth a shit.