Fuel Injectors
Discussion
Thought I would share my findings with the big power boys,.
After taking all the data from my ecu(F90) and giving it to Terry, it turns out that my ecu has been pulling spark and ign out to save the engine from running lean, which in turn has saved my engine blowing up for a second time, on his advice i sent my seimens 605cc injectors off to have them flow checked, it turns out that these injectors should only run at 85% of max output, which is absolutely inadequate for over 500bhp,
I think this has been the cause of my probs, I am now having some ASNU900cc flowed for my car with a spray pattern that is not all over the place as the seimens 605
are, for those that may be interested i am waiting for the cost per injector so will let you know.
My engine is back on the bench dyno next week with the new injectors fitted so will let you know the improvements.
Just a word of caution to 600 boys who still run on 605cc be careful you are running lean and if you still run a MBE ecu you have no way of saving youre engine
After taking all the data from my ecu(F90) and giving it to Terry, it turns out that my ecu has been pulling spark and ign out to save the engine from running lean, which in turn has saved my engine blowing up for a second time, on his advice i sent my seimens 605cc injectors off to have them flow checked, it turns out that these injectors should only run at 85% of max output, which is absolutely inadequate for over 500bhp,
I think this has been the cause of my probs, I am now having some ASNU900cc flowed for my car with a spray pattern that is not all over the place as the seimens 605
are, for those that may be interested i am waiting for the cost per injector so will let you know.
My engine is back on the bench dyno next week with the new injectors fitted so will let you know the improvements.
Just a word of caution to 600 boys who still run on 605cc be careful you are running lean and if you still run a MBE ecu you have no way of saving youre engine
what fuel pressure do you run?... trevor recommended I turned mine up quite a bit from stock and I have not had issues, will check when back in UK but pretty sure my max duty is around 90%.
Regardless Id be interested in an injector that is better controlled so I can smooth out the idle and below 2000rpm drivability.
Regardless Id be interested in an injector that is better controlled so I can smooth out the idle and below 2000rpm drivability.
Hollowpockets said:
What pump set up do you have Craig? Will the newer ECU with wideband and knock sensing be able to protect a against this or not? Also will water injection help?
Interested to see how you get on.
Hi Graham, I have twin 044s, but i use a differnt fuel rail, where mine pushes the fuel at one end and sucks at the other.Interested to see how you get on.
Thankfully I have a wideband in the life F90 ecu so yes it totally saved the engine,
Dont think water injection will help this problem, there just isnt enough flow for our power.
My engine has just come back from Mountune and was given a clean bill of health so i cant ask for more proof of how the system has worked and protected the engine all thropugh the problems and all the rolling road work,
It also showed the reason it was so hard to map drive ability as the ecu was constantly having to correct to make up for lack of fuel.
Also on your race car with a wideband you can have 12 different map settings to suit different tracks and conditions it really is a win win, and with the added wheel sensors traction control for getting out the corners faster and the starts
Edited by sundance002 on Thursday 27th March 16:16
Edited by sundance002 on Thursday 27th March 16:20
andygtt said:
what fuel pressure do you run?... trevor recommended I turned mine up quite a bit from stock and I have not had issues, will check when back in UK but pretty sure my max duty is around 90%.
Regardless Id be interested in an injector that is better controlled so I can smooth out the idle and below 2000rpm drivability.
Hi Andy, not sure the exact pressure but much higher than stock, the problem with the 605s is they cant keep up on full chat, and over time create engine problems that go bang with no warningRegardless Id be interested in an injector that is better controlled so I can smooth out the idle and below 2000rpm drivability.
Craig, I have the wideband sensors, knock and 3 maps on mine with the new MBE so that gives me piece of mind over the standard set up I had last year.
Is it possible that because your fuel rail 'sucks or flows out' at the other end, that the two pumps struggle to maintain a constant pressure, whereas our standard rail will build up a bigger pressure behind the injectors?
It wouldn't be right to assume our injectors suffer the same problem as they have a different set up.
Is there anyone (Kev??) who data logs with a standard fuel rail and the same 044's and injectors who can verify if running lean is a problem?
Cheers
G
Is it possible that because your fuel rail 'sucks or flows out' at the other end, that the two pumps struggle to maintain a constant pressure, whereas our standard rail will build up a bigger pressure behind the injectors?
It wouldn't be right to assume our injectors suffer the same problem as they have a different set up.
Is there anyone (Kev??) who data logs with a standard fuel rail and the same 044's and injectors who can verify if running lean is a problem?
Cheers
G
Hollowpockets said:
Craig, I have the wideband sensors, knock and 3 maps on mine with the new MBE so that gives me piece of mind over the standard set up I had last year.
Is it possible that because your fuel rail 'sucks or flows out' at the other end, that the two pumps struggle to maintain a constant pressure, whereas our standard rail will build up a bigger pressure behind the injectors?
It wouldn't be right to assume our injectors suffer the same problem as they have a different set up.
Is there anyone (Kev??) who data logs with a standard fuel rail and the same 044's and injectors who can verify if running lean is a problem?
Cheers
G
Graham thats not how mine works, the first pump pushes the fuel, the second pump is a secondary one that only cuts in if the first one fails, in standard form they used to suck the fuel on a single pump and thats why the line used to collapse. The only reason my fuel rail is different is because i have a different loom for the F90 ecu.Is it possible that because your fuel rail 'sucks or flows out' at the other end, that the two pumps struggle to maintain a constant pressure, whereas our standard rail will build up a bigger pressure behind the injectors?
It wouldn't be right to assume our injectors suffer the same problem as they have a different set up.
Is there anyone (Kev??) who data logs with a standard fuel rail and the same 044's and injectors who can verify if running lean is a problem?
Cheers
G
It dont matter to me if you change or not, the flow charts clearly show they are not up to it, send urs off and get them checked, than mention you are running over 600bhp with them, see what they tell you. just saying
PS mine is no different to yours unless the main pump fails
Im just giving you guys a heads up, remember the man who gives me the info does happen to work trackside F1 for Merc so i assume he knows how to read the data and set a car up, next time i wont bother
Edited by sundance002 on Thursday 27th March 20:12
Agree Craig that the Siemens black 630cc injectors are running at high duty cycle when on high boost, however I'm not seeing any problems from it & afr's are fine even at high rpm.
Guess different mappers have there own ideas of what's right & wrong, EPS tune a lot of race cars & did all my mapping on a runway to ensure the engine is fully loaded & then checked on a Dyno. On track you sometimes see from the logging upto 95% duty cycle at full chat but everything is running fine & l only run one 044 pump with the second only as a standby.
Guess different mappers have there own ideas of what's right & wrong, EPS tune a lot of race cars & did all my mapping on a runway to ensure the engine is fully loaded & then checked on a Dyno. On track you sometimes see from the logging upto 95% duty cycle at full chat but everything is running fine & l only run one 044 pump with the second only as a standby.
GTO600 said:
Agree Craig that the Siemens black 630cc injectors are running at high duty cycle when on high boost, however I'm not seeing any problems from it & afr's are fine even at high rpm.
Guess different mappers have there own ideas of what's right & wrong, EPS tune a lot of race cars & did all my mapping on a runway to ensure the engine is fully loaded & then checked on a Dyno. On track you sometimes see from the logging upto 95% duty cycle at full chat but everything is running fine & l only run one 044 pump with the second only as a standby.
I to only run one pump the second as a standby, my point is that they should only run at 85% max, when new no problem but it doesnt take much for them to run lean ie a micron of dirt which is easily poss after a few miles is enough to cause a failure on full chat, why take the risk as better to have a larger injector with room, why run everything on max and above. Im waiting to hear what Grant has to say when he gets his back from being checked and flowed after his massive failure, it will only confirm what im saying, that normal wear will bring them down down an average of 3 to 4 percent per injector as mine were which after a few track days is easy possible, Guess different mappers have there own ideas of what's right & wrong, EPS tune a lot of race cars & did all my mapping on a runway to ensure the engine is fully loaded & then checked on a Dyno. On track you sometimes see from the logging upto 95% duty cycle at full chat but everything is running fine & l only run one 044 pump with the second only as a standby.
Hollowpockets said:
Haha, Craig don't get the wrong end of the stick, I appreciate your sharing info, I'm just trying to understand if the difference between the set ups could have an effect on the pressure/flow as it's not something that's ever been noticed before and I'm no expert.
Cheers
Sorry Graham woke up grumpy,Cheers
The only difference on my car to the other600 boys is that i have more safety features fitted which is why it highlights the problems so early, i have sensors and controlled regulators on everything i can also control flow and pressure, i am deff not an expert but i can trust the advice and help given by Terry who does it for nothing, and who set the hole thing up. What he says is does it work yes is it safe no because there is no room for error
It might be worth a quick note on "headroom" and how it applies to fuel injectors!
Fuel injectors are generally rated at "fully open" or the "piss 'em into a bucket" test. In this test, the injectors are energised for say 30sec to a min, at a given fuel rail pressure, and the fuel squirted out is collected and the volume (or mass) measured. Whilst this is a decent way of comparing injectors it necessarily doesn't take into account the "dynamic flow" of either the injectors or the rest of the fuel system as installed. A fuel injector is a solenoid valve, and it takes a finite time to open and close (typically around 1 to 2ms to open, and about 0.5ms to close. it's non symmetrical due to the way they are driven and the direction that fuel pressure acts on the pintle).
As each injector muct open to inject fuel and then close, unless you are running a non sequential injection system (like we used to back in the day!) then you never really approach having each injector continuously on, and as such, you cannot approach the measured "bucket" flow test. Typically, most injectors will reach there practical flow limit at around 85% duty cycle. As such, mapping you car to regularly use the full 85% range is a bit silly really.
It's also worth noting that unless you are doing a full OEM style calibration you won't have the luxury of running your car and mapping it under all possible boundary conditions, by which i mean, air temp, air pressure, boost pressures, coolant temp, fuel temps, battery voltages, etc. This means that leaving a reasonable "Headroom" for the maximum injector duty cycle is a really good idea, especially with turbo cars (that have a much wider range of manifold temps) and cars with active knock control / EGT correction (that modify fuel pulse width in response to cylinder knock etc. Then you get into ageing effects, both in the injector and the rest of the engine components, with closed loop lambda corrections etc, which can easily be 5-10%.
All of those factors can add up in certain circumstances (often, they negate each other depending on the direction (lean or rich) of each individual trim and parameter) and as a result, you may find your engine running lean as the EMS tries to exceed the normal 85% injector duty, which as this thread shows, is a bad thing!
So, my recommendation, assuming you don't have an EMS that can dynamically increase fuel pressure (like modern OEM ones), is to target a basic injector duty cycle maximum of no more than 75% during mapping activities. If you live somewhere that gets very cold, you might want to even go lower than that (say 70%) to allow sufficient headroom for increased air density on cold days.
The other factor that most people simple don't realise is that with a conventional fuel pressure regulator that returns excess fuel from the end of the rail back to the tank, is that your fuel rail pressure setting only actually makes your set pressure at the load condition you set it (often idle!) All FPRs have a spring rate, and with a non flow controlled pump, they are at their maximum opening at max return flow (idle) and as such maintain a maximum rail pressure. However, as the return flow falls as the injectors injector a larger and larger mass into the engine, the regulated pressure WILL fall. Some of the FPRs i have tested are absolutely terrible in this respect, dropping nearly 1bar across their flow range!.
On top of all that, there are dynamic effects like rail pressure fluctuations and standing waves, the effect of fuel temp and driving voltage on fuel pump performance, and dynamic flow losses in the fuel lines! In fact, it's a very complicated system if you sit down to work through the physics of it!.
All this paints a picture where leaving sufficient dynamic headroom in your injection max duty is a vital basic step in any mapping/calibration activity......
Fuel injectors are generally rated at "fully open" or the "piss 'em into a bucket" test. In this test, the injectors are energised for say 30sec to a min, at a given fuel rail pressure, and the fuel squirted out is collected and the volume (or mass) measured. Whilst this is a decent way of comparing injectors it necessarily doesn't take into account the "dynamic flow" of either the injectors or the rest of the fuel system as installed. A fuel injector is a solenoid valve, and it takes a finite time to open and close (typically around 1 to 2ms to open, and about 0.5ms to close. it's non symmetrical due to the way they are driven and the direction that fuel pressure acts on the pintle).
As each injector muct open to inject fuel and then close, unless you are running a non sequential injection system (like we used to back in the day!) then you never really approach having each injector continuously on, and as such, you cannot approach the measured "bucket" flow test. Typically, most injectors will reach there practical flow limit at around 85% duty cycle. As such, mapping you car to regularly use the full 85% range is a bit silly really.
It's also worth noting that unless you are doing a full OEM style calibration you won't have the luxury of running your car and mapping it under all possible boundary conditions, by which i mean, air temp, air pressure, boost pressures, coolant temp, fuel temps, battery voltages, etc. This means that leaving a reasonable "Headroom" for the maximum injector duty cycle is a really good idea, especially with turbo cars (that have a much wider range of manifold temps) and cars with active knock control / EGT correction (that modify fuel pulse width in response to cylinder knock etc. Then you get into ageing effects, both in the injector and the rest of the engine components, with closed loop lambda corrections etc, which can easily be 5-10%.
All of those factors can add up in certain circumstances (often, they negate each other depending on the direction (lean or rich) of each individual trim and parameter) and as a result, you may find your engine running lean as the EMS tries to exceed the normal 85% injector duty, which as this thread shows, is a bad thing!
So, my recommendation, assuming you don't have an EMS that can dynamically increase fuel pressure (like modern OEM ones), is to target a basic injector duty cycle maximum of no more than 75% during mapping activities. If you live somewhere that gets very cold, you might want to even go lower than that (say 70%) to allow sufficient headroom for increased air density on cold days.
The other factor that most people simple don't realise is that with a conventional fuel pressure regulator that returns excess fuel from the end of the rail back to the tank, is that your fuel rail pressure setting only actually makes your set pressure at the load condition you set it (often idle!) All FPRs have a spring rate, and with a non flow controlled pump, they are at their maximum opening at max return flow (idle) and as such maintain a maximum rail pressure. However, as the return flow falls as the injectors injector a larger and larger mass into the engine, the regulated pressure WILL fall. Some of the FPRs i have tested are absolutely terrible in this respect, dropping nearly 1bar across their flow range!.
On top of all that, there are dynamic effects like rail pressure fluctuations and standing waves, the effect of fuel temp and driving voltage on fuel pump performance, and dynamic flow losses in the fuel lines! In fact, it's a very complicated system if you sit down to work through the physics of it!.
All this paints a picture where leaving sufficient dynamic headroom in your injection max duty is a vital basic step in any mapping/calibration activity......
Yes, although you may get diminishing returns as the pressure increases.
The duty cycle discussion here, and the points raised are all good stuff, however it's a bit redundant with our original ECUs.
eg Taking Craigs point about injector performance dropping over time or with a small blockage - having an injector that is running at a lower duty cycle would not make any difference as the ECU will not know that, as we do not have wideband AFR capability and so no closed loop control.
The nice big injector will still be putting too little fuel in as nothing has told it to to use some of that spare duty cycle.......
The duty cycle discussion here, and the points raised are all good stuff, however it's a bit redundant with our original ECUs.
eg Taking Craigs point about injector performance dropping over time or with a small blockage - having an injector that is running at a lower duty cycle would not make any difference as the ECU will not know that, as we do not have wideband AFR capability and so no closed loop control.
The nice big injector will still be putting too little fuel in as nothing has told it to to use some of that spare duty cycle.......
Hollowpockets said:
Craig, I have the wideband sensors, knock and 3 maps on mine with the new MBE so that gives me piece of mind over the standard set up I had last year.
Is it possible that because your fuel rail 'sucks or flows out' at the other end, that the two pumps struggle to maintain a constant pressure, whereas our standard rail will build up a bigger pressure behind the injectors?
It wouldn't be right to assume our injectors suffer the same problem as they have a different set up.
Is there anyone (Kev??) who data logs with a standard fuel rail and the same 044's and injectors who can verify if running lean is a problem?
Cheers
G
I run logging and have the rail the same as Sundance i.e. it goes in the peer steering side and returns on the original entry.... I have not had any go lean issues at all with the injectors maxing out either on track road or on the dyne... I have fuel pressure, temp, wideband and EGT monitored in the logging.Is it possible that because your fuel rail 'sucks or flows out' at the other end, that the two pumps struggle to maintain a constant pressure, whereas our standard rail will build up a bigger pressure behind the injectors?
It wouldn't be right to assume our injectors suffer the same problem as they have a different set up.
Is there anyone (Kev??) who data logs with a standard fuel rail and the same 044's and injectors who can verify if running lean is a problem?
Cheers
G
Only time mine has gone lean and gone into limp mode is when I ran out of fuel because my petrol gauge was lying
Must say I would be interested in changing as I would like better control on idle and less duty... is this possible?
Edited by andygtt on Friday 28th March 10:06
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