Balancing Fuel Injectors
Discussion
I had all 6 of my injectors cleaned and flow checked when I first bought my ’91 SE. I found a local place via the yellow pages. It took a day or two to get them back, and it cost $60 (US). I don’t know if they were perfectly balanced or not, but they said that they were all within specs, and the car runs exceptionally well.
I don’t know exactly where you live, but for example, I looked up “Fuel Injection” on the “Yahoo Yellow Pages” for Atlanta, GA, and found two shops. Here are the search results.
http://yp.yahoo.com/py/ypResults.py?stx=fuel+injection&stp=a&tab=B2C&city=Atlanta&state=GA&country=us&msa=0520&slt=33.748657&sln=-84.387711&cs=4&Submit=Search
Good luck…Walt ’91 SE.
I don’t know exactly where you live, but for example, I looked up “Fuel Injection” on the “Yahoo Yellow Pages” for Atlanta, GA, and found two shops. Here are the search results.
http://yp.yahoo.com/py/ypResults.py?stx=fuel+injection&stp=a&tab=B2C&city=Atlanta&state=GA&country=us&msa=0520&slt=33.748657&sln=-84.387711&cs=4&Submit=Search
Good luck…Walt ’91 SE.
Hi,
No such thing as balancing your fuel injectors. They can be flow tested and those not producing the same flow can be replaced with one which do. But, you cannot alter the existing injector (at least not easily without a total rebuild which is economically unfeasible).
But, while you can match injectors on a bench, you may not find the same characteristics once the injectors are installed. This is due to variations in fuel pressure which can occur in the fuel rail, ie. the first injector gets a little better pressure than the last one feeding from the rail. Also, as your ECU adapts dynamically, as it senses the Lamda reading from the 0² sensor from the previous cylinder (actually about 6 combustions back), it can adjust the fuel pressure to a particular injector giving it a totally different flow and duration than the others.
That having been said, if they are matched on a bench, you do probably get slightly better performance (not necessarily more power or HP at all). Most injectors with the same stock number will perform within a tolerance sufficient for most street engines though. So, unless they're practically giving away the service, personally I'd forego it as any improvement would probably not even be noticeable unless you were dyno testing on an otherwise perfect engine. Happy Motoring! Jim'85TE
>> Edited by lotusguy on Tuesday 22 April 20:42
No such thing as balancing your fuel injectors. They can be flow tested and those not producing the same flow can be replaced with one which do. But, you cannot alter the existing injector (at least not easily without a total rebuild which is economically unfeasible).
But, while you can match injectors on a bench, you may not find the same characteristics once the injectors are installed. This is due to variations in fuel pressure which can occur in the fuel rail, ie. the first injector gets a little better pressure than the last one feeding from the rail. Also, as your ECU adapts dynamically, as it senses the Lamda reading from the 0² sensor from the previous cylinder (actually about 6 combustions back), it can adjust the fuel pressure to a particular injector giving it a totally different flow and duration than the others.
That having been said, if they are matched on a bench, you do probably get slightly better performance (not necessarily more power or HP at all). Most injectors with the same stock number will perform within a tolerance sufficient for most street engines though. So, unless they're practically giving away the service, personally I'd forego it as any improvement would probably not even be noticeable unless you were dyno testing on an otherwise perfect engine. Happy Motoring! Jim'85TE
>> Edited by lotusguy on Tuesday 22 April 20:42
Thank You Calvin, and thank you Walt- I will look into the links you posted.
Jim, I appreciate your input but in my world when two injectors are matched to within 1% flow rate of each other at their maximum input voltage and 1% at their minimum input voltage, I call it balanced. No different than balancing pistons and rods. It equals efficiency. Efficiency promotes bhp. Although I have not had this service done with these particular injectors, I have on several occasions had factory injectors that flow 193 CC/min opened to flow 231 CC/min and "flow matched" to within 1% of each other. I first consulted the company who performed this work for me but they are not familar with Lotus, thus I come to this forum. I replaced the fuel pump a few weeks ago due to a decrease in performance when a loud whine coming from the fuel pump would develop after driving for several miles. On opening the pump I discovered that the pump was failing from two things. The brushes were very worn, and 12 years of pump fuel and rust had partially clogged the passages. There are no more symptoms, performance restored. But you as well as I know that 12 years of pump fuel and rust, even with proper filter changes, will accumulate in the injectors disrupting spray patterns, thus decreasing efficiency. They need to be cleaned and it only makes logical sence to have then "balanced" at the same time.
John C. Anderson
Jim, I appreciate your input but in my world when two injectors are matched to within 1% flow rate of each other at their maximum input voltage and 1% at their minimum input voltage, I call it balanced. No different than balancing pistons and rods. It equals efficiency. Efficiency promotes bhp. Although I have not had this service done with these particular injectors, I have on several occasions had factory injectors that flow 193 CC/min opened to flow 231 CC/min and "flow matched" to within 1% of each other. I first consulted the company who performed this work for me but they are not familar with Lotus, thus I come to this forum. I replaced the fuel pump a few weeks ago due to a decrease in performance when a loud whine coming from the fuel pump would develop after driving for several miles. On opening the pump I discovered that the pump was failing from two things. The brushes were very worn, and 12 years of pump fuel and rust had partially clogged the passages. There are no more symptoms, performance restored. But you as well as I know that 12 years of pump fuel and rust, even with proper filter changes, will accumulate in the injectors disrupting spray patterns, thus decreasing efficiency. They need to be cleaned and it only makes logical sence to have then "balanced" at the same time.
John C. Anderson
You brought up a good point Lotusguy regarding the fuel rail. I had been told that the secondary injector on the first cylinder had been put in by Lotus because the cylinder was being starved as the hp went up in years after 1990 or so. The piston was being burned due to lean fuel mix. Correct? Why wasn't the ID of the fuel rail increased to avoid the line loss in the rail. Should those of us putting in HP enhancement of earlier year cars consider putting in a rail with a bigger ID since we cannot put in a secondary injector?
Bob Kumse
'89 non SE
Bob Kumse
'89 non SE
5150neo said: Thank You Calvin, and thank you Walt- I will look into the links you posted.
Jim, I appreciate your input but in my world when two injectors are matched to within 1% flow rate of each other at their maximum input voltage and 1% at their minimum input voltage, I call it balanced. No different than balancing pistons and rods. It equals efficiency. Efficiency promotes bhp. Although I have not had this service done with these particular injectors, I have on several occasions had factory injectors that flow 193 CC/min opened to flow 231 CC/min and "flow matched" to within 1% of each other. I first consulted the company who performed this work for me but they are not familar with Lotus, thus I come to this forum. I replaced the fuel pump a few weeks ago due to a decrease in performance when a loud whine coming from the fuel pump would develop after driving for several miles. On opening the pump I discovered that the pump was failing from two things. The brushes were very worn, and 12 years of pump fuel and rust had partially clogged the passages. There are no more symptoms, performance restored. But you as well as I know that 12 years of pump fuel and rust, even with proper filter changes, will accumulate in the injectors disrupting spray patterns, thus decreasing efficiency. They need to be cleaned and it only makes logical sence to have then "balanced" at the same time.
John C. Anderson
John,
It may be an issue of semantics, but balancing and matching are not the same thing. To say that injectors are 'balanced' is simply a misnomer.
Of course, in a free society, you are free to call them 'snaggleclapped' if you like. But it may be confusing to those less knowledgeable. Happy Motoring! Jim'85TE
lotusguy said: But, while you can match injectors on a bench, you may not find the same characteristics once the injectors are installed. This is due to variations in fuel pressure which can occur in the fuel rail, ie. the first injector gets a little better pressure than the last one feeding from the rail. Also, as your ECU adapts dynamically, as it senses the Lamda reading from the 0² sensor from the previous cylinder (actually about 6 combustions back), it can adjust the fuel pressure to a particular injector giving it a totally different flow and duration than the others.
I'm not sure I know enough to chime in here, but it seems to me that since the rail and its attendant plumping are in a loop from/to the fuel pump that the pressure at any point in the rail is going to be the same no matter what. Or am I missing something?
Additionally, I doubt if the ECM really changes the pulse duration to individual cylinders in response to O2 signals, all other factors being equal. Since the Delco ECM controls the injectors in pairs (1-4 and 2-3), this is certainly impossible other than on a more global basis.
Cheers,
Sanj
I've got to stick my $.02 in here as well...
The ECU "gang fires" two main injectors at a time, and has no direct relation from the O2 reading to which cylinder fired. The O2 sensor is much too slow to react to the changes in the exhaust stream to be useful for cylinder by cylinder combustion control.
As for fuel pressure, the fuel pressure regulator has a pulsation damper in it that "smooths" out the rail pressure. You could tap the rail or feed lines at any point, and see the same pressure, because it is a closed loop system.
However unless you are using a VERY good electronic meter and a VERY good transducer at a sampling rate above 500hz your not going to detect the varaitions in the fuel rail pressures.
The ECU "gang fires" two main injectors at a time, and has no direct relation from the O2 reading to which cylinder fired. The O2 sensor is much too slow to react to the changes in the exhaust stream to be useful for cylinder by cylinder combustion control.
As for fuel pressure, the fuel pressure regulator has a pulsation damper in it that "smooths" out the rail pressure. You could tap the rail or feed lines at any point, and see the same pressure, because it is a closed loop system.
However unless you are using a VERY good electronic meter and a VERY good transducer at a sampling rate above 500hz your not going to detect the varaitions in the fuel rail pressures.
5150neo said: Squelch,
The preasure regulator is the one part of the system I never fully understood. When preasure is present, is the damper accuated by a preset spring tension or vaccume acting on the damper or a combination of both?
Hi,
The fuel pressure regulator is accuated by both a spring and vacuum pressure. The vacuum pressure allows more pressure in high RPM/boost mode. Happy Motoring! Jim'85TE
lotusguy said:
Hi,
The fuel pressure regulator is accuated by both a spring and vacuum pressure. The vacuum pressure allows more pressure in high RPM/boost mode. Happy Motoring! Jim'85TE
Actually the regulator is controlled by spring pressure and manifold pressure, it can be vacuum or boost.
The fuel injectors needs to "feel" a certain pressure differential across it.
Fuel injectors are designed to work with specific fuel pressures to make specific spray patterns and flow rates.
Lets take an example:
One end of the injector is in the manifold, and the other end is in the fuel rail and the rail pressure with the engine off would be... lets say 40psi..
With the engine at idle there is vacuum in the manifold and vacuum is applied to the regulator, that would lower the fuel pressure, at 20" of vacuum the fuel pressure would be about 30 psi
However, since the injector has one end in the rail and one in the manifold, the injectors still "feels" 40psi across it... one end of the injector is in vacuum and the other in 30 psi of pressure...
When on boost just the opposite is true, there may be 15psi of boost in the manifold, and 15 psi applied to the regulator so the fuel pressure is now 55psi (at least to us out here in the atomsphere) but to the injector.. it still "feels" only 40 psi of fuel pressure...
55 psi of rail pressure working against 15psi of manifold pressure... 40psi differential..
The fuel pressure regulator keeps the correct pressure to the injectors with referance to the manifold pressure.
These are rough numbers but you get the idea...
John
Makes perfect sence to me. I appreciate the example. But thinking ahead to possible situations, if the regulator were to malfunction in the presence of manifold preasure only and not in the presence of vacume, what do you think the symptoms would be? Well, some of the symptoms would be quite obvious. Let me ask that again. How do you think the computer would react to this situation?
John
John
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