Question about injectors
04-02-2018, 11:03 AM
#41
TECH Fanatic
1. This happens if you don't tune the engine properly. You need to set the injector phase to fire the large enough injector after overlap. Even gen3 ecu can do this and basically every stand-alone in existence.
2. You should not be using closed loop at idle with a big cam, unnecessary and leads to these kinds of ridiculous complications
3. I never use closed loop in any of my cars at any time anyways. If you know how to tune an engine you won't need it or want it either. It would get worse fuel economy with computer control closed loop in my application (daily).
4. You have to use a little common sense and experience when tuning low speed with a wideband. 100+ cars and I've never had an issue following it at idle, even with enormous camshafts etc... I know tons of tricks for this. If you want some tricks lmk Ill post a couple but theres like 10 I know of,
A: Just off idle the pulse will be similar to idle. So if the wideband is giving you **** with no load/neutral at 1000rpm, simply put it in gear and let the car roll "load a little" to 1200rpm and check your injector pulse / wideband behavior. As the engine loads it will get smoother as more fuel is injected and the average improves. Apply the brakes to further assist with low rpm / load condition.
B: reducing injector pulse until the engine misfires at random is a clear indicator that injector on-time is at it's minimum. This is important because a large injector with poor low-pulse performance is going to give more trouble with idle speed behavior, especially if the a/f being displayed is still too rich and you cannot reduce pulse further for example. This basically sets the minimum pulse FOR YOU (as opposed to any reading on the wideband gauge, which is meaningless at this point because you can't reduce pulse enough to get it where you want it) Again I know work around but... space concerns ... just ask
C: &C
2. You should not be using closed loop at idle with a big cam, unnecessary and leads to these kinds of ridiculous complications
3. I never use closed loop in any of my cars at any time anyways. If you know how to tune an engine you won't need it or want it either. It would get worse fuel economy with computer control closed loop in my application (daily).
4. You have to use a little common sense and experience when tuning low speed with a wideband. 100+ cars and I've never had an issue following it at idle, even with enormous camshafts etc... I know tons of tricks for this. If you want some tricks lmk Ill post a couple but theres like 10 I know of,
A: Just off idle the pulse will be similar to idle. So if the wideband is giving you **** with no load/neutral at 1000rpm, simply put it in gear and let the car roll "load a little" to 1200rpm and check your injector pulse / wideband behavior. As the engine loads it will get smoother as more fuel is injected and the average improves. Apply the brakes to further assist with low rpm / load condition.
B: reducing injector pulse until the engine misfires at random is a clear indicator that injector on-time is at it's minimum. This is important because a large injector with poor low-pulse performance is going to give more trouble with idle speed behavior, especially if the a/f being displayed is still too rich and you cannot reduce pulse further for example. This basically sets the minimum pulse FOR YOU (as opposed to any reading on the wideband gauge, which is meaningless at this point because you can't reduce pulse enough to get it where you want it) Again I know work around but... space concerns ... just ask
C: &C
Just use the damn data kids. And don't do drugs.
04-02-2018, 11:23 AM
#42
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S/S 160's Injector Min PW = .813ms Hi ALL, I am SURE that if I state the Min PW for the Ford ALT Fuel Injector (160) is .813ms, the one I provide to some here on LS-1 Tech, I will catch HELL.
WHAT WAS FOUND : The .813 MS Min PW was measured by a scope finding Armature Position was at FULL TRAVEL.
The engine had a quality Idle, a LS-396.
The Fuel Pressure was at 65psi.
The increase of Line Pressure from the 43.5 (1.213ms) to 65 (.813ms) allowed the injector to operate at the LOWER Min PW.
This resulted in LESS Fuel at Idle Speed/Idle Load being delivered into the cylinder.
I AGREE that the "King" tech has some merit though a bit Vague.
YES, the Injection Instant (timing at low PW) is VERY IMPORTANT with MY ADVICE of that amount of fuel injected into a Port when the Inlet Valve is FULL OPEN or about 420-450 degrees in the cycle.
I ALWAYS run "closed loop" EGO control, the difference is MY AFR Map is set to what the engine likes to run best at NOT a "guess" of the "SHOULD BE" AFR.
NOW, to explain rich "miss-fire" as seen by the EGO/UEGO at times as a find of Oxygen in the exhaust stream, extra Oxygen is a leftover from poor combustion.
Lance
WHAT WAS FOUND : The .813 MS Min PW was measured by a scope finding Armature Position was at FULL TRAVEL.
The engine had a quality Idle, a LS-396.
The Fuel Pressure was at 65psi.
The increase of Line Pressure from the 43.5 (1.213ms) to 65 (.813ms) allowed the injector to operate at the LOWER Min PW.
This resulted in LESS Fuel at Idle Speed/Idle Load being delivered into the cylinder.
I AGREE that the "King" tech has some merit though a bit Vague.
YES, the Injection Instant (timing at low PW) is VERY IMPORTANT with MY ADVICE of that amount of fuel injected into a Port when the Inlet Valve is FULL OPEN or about 420-450 degrees in the cycle.
I ALWAYS run "closed loop" EGO control, the difference is MY AFR Map is set to what the engine likes to run best at NOT a "guess" of the "SHOULD BE" AFR.
NOW, to explain rich "miss-fire" as seen by the EGO/UEGO at times as a find of Oxygen in the exhaust stream, extra Oxygen is a leftover from poor combustion.
Lance
04-02-2018, 11:45 AM
#43
TECH Fanatic
I am not disagreeing with injector timing or even min pulse width adjustments being very important. I'm simply stating the fact that many cams can and will cause the false lean condition at low rpm, especially idle. When in closed loop min pulse width becomes the control for this, or just doing the OL idle set up depending on the car and application.
I prefer to use MAF above 1200, and do OL at low rpm because of its tendency to cause some surging in certain conditions. Otherwise I have to mess around with O2 delay and switching points to calm it down when it gets the air from overlap. I've found mine idles best at 15.5 afr at idle. Sometimes it likes even less than that. No surging or any other issues. Cam is 297/305 .634/634, 114+4. And it's a stroker. I've tuned a few large cams, but this one was a bit challenging. Not as challenging as finding time to do it though.
And yes poor combustion can cause lean running engines, but as you stated it's all about what the engine likes. When you have an intake valve that is open for 1/3 of the exhaust stroke as the piston is moving up, you're bound to push some fresh air directly into the header. This cam seems to like 16* of timing and 15.5 afr. The last one liked 16:1 afr. Running it at stoich causes some surging. Duty cycle is what it should be, likewise with pw. VE still has control over these values, so min pw is perfectly good.
And everything talon says is vauge so he doesn't have to back it up with solid information.
I prefer to use MAF above 1200, and do OL at low rpm because of its tendency to cause some surging in certain conditions. Otherwise I have to mess around with O2 delay and switching points to calm it down when it gets the air from overlap. I've found mine idles best at 15.5 afr at idle. Sometimes it likes even less than that. No surging or any other issues. Cam is 297/305 .634/634, 114+4. And it's a stroker. I've tuned a few large cams, but this one was a bit challenging. Not as challenging as finding time to do it though.
And yes poor combustion can cause lean running engines, but as you stated it's all about what the engine likes. When you have an intake valve that is open for 1/3 of the exhaust stroke as the piston is moving up, you're bound to push some fresh air directly into the header. This cam seems to like 16* of timing and 15.5 afr. The last one liked 16:1 afr. Running it at stoich causes some surging. Duty cycle is what it should be, likewise with pw. VE still has control over these values, so min pw is perfectly good.
And everything talon says is vauge so he doesn't have to back it up with solid information.
Last edited by ChopperDoc; 04-02-2018 at 11:54 AM. Reason: Autocorrect sucks
04-02-2018, 12:30 PM
#44
TECH Fanatic
Hi ALL, I am SURE that if I state the Min PW for the Ford ALT Fuel Injector (160) is .813ms, the one I provide to some here on LS-1 Tech, I will catch HELL.
WHAT WAS FOUND : The .813 MS Min PW was measured by a scope finding Armature Position was at FULL TRAVEL.
The engine had a quality Idle, a LS-396.
The Fuel Pressure was at 65psi.
The increase of Line Pressure from the 43.5 (1.213ms) to 65 (.813ms) allowed the injector to operate at the LOWER Min PW.
This resulted in LESS Fuel at Idle Speed/Idle Load being delivered into the cylinder.
I AGREE that the "King" tech has some merit though a bit Vague.
YES, the Injection Instant (timing at low PW) is VERY IMPORTANT with MY ADVICE of that amount of fuel injected into a Port when the Inlet Valve is FULL OPEN or about 420-450 degrees in the cycle.
I ALWAYS run "closed loop" EGO control, the difference is MY AFR Map is set to what the engine likes to run best at NOT a "guess" of the "SHOULD BE" AFR.
NOW, to explain rich "miss-fire" as seen by the EGO/UEGO at times as a find of Oxygen in the exhaust stream, extra Oxygen is a leftover from poor combustion.
Lance
WHAT WAS FOUND : The .813 MS Min PW was measured by a scope finding Armature Position was at FULL TRAVEL.
The engine had a quality Idle, a LS-396.
The Fuel Pressure was at 65psi.
The increase of Line Pressure from the 43.5 (1.213ms) to 65 (.813ms) allowed the injector to operate at the LOWER Min PW.
This resulted in LESS Fuel at Idle Speed/Idle Load being delivered into the cylinder.
I AGREE that the "King" tech has some merit though a bit Vague.
YES, the Injection Instant (timing at low PW) is VERY IMPORTANT with MY ADVICE of that amount of fuel injected into a Port when the Inlet Valve is FULL OPEN or about 420-450 degrees in the cycle.
I ALWAYS run "closed loop" EGO control, the difference is MY AFR Map is set to what the engine likes to run best at NOT a "guess" of the "SHOULD BE" AFR.
NOW, to explain rich "miss-fire" as seen by the EGO/UEGO at times as a find of Oxygen in the exhaust stream, extra Oxygen is a leftover from poor combustion.
Lance
As far as the EOIT, 420* seems awfully late, as I've found on at least gen III pcms because this is a single value. If there was a way to do it like a gen IV then I could see that working, but considering boiling time and evap vs washing the cylinder down in the middle of the stroke, just seems late. Not saying it doesn't work, since I'm sure you know your stuff, but anything past 379* for mine is too late and causes lots of fuel in my puke tank, more than usual. That and it runs horrible if I keep pushing this number past it's happy place. There is a LONG discussion on this on the hp tuners forum, with many schools of thought as to when this should occur. My thought on it is, so long as it's after 360, it's pulling vacuum, and gives some time for evap to occur vs washing the cylinder. There are so many variables here a single value isn't going to apply engine to engine, in my opinion. It's all about that happy place.
This is really more to get the smell down and doesn't seem to have a huge effect on afr unless it's way too early or way too late.
04-02-2018, 12:52 PM
#45
I am not disagreeing with injector timing or even min pulse width adjustments being very important. I'm simply stating the fact that many cams can and will cause the false lean condition at low rpm, especially idle....
...And yes poor combustion can cause lean running engines, but as you stated it's all about what the engine likes.
...And yes poor combustion can cause lean running engines, but as you stated it's all about what the engine likes.
Since you are making such a big deal about it, let me ask you: Why do you care about false lean condition? I want my wideband to show me a lean number idle. You answered your own question "what the engine likes" statement- it means the same thing I've been saying all alone: Find the minimum on-time and minimum injection to get the engine to run then set your minimums from that, and add fuel until the engine likes. Who cares if the number on the gauge is right or wrong? I have a news flash: its always wrong. Its always an estimate. You can't know the a/f for each cylinder if there are eight of them and only 1 wideband sensor.
Its not like knowing the actual a/f ratio has any bearing whatsoever on our idle condition, so why are you so uptight about what you think is the correct number on the wideband gauge has anything to do with it? After all, its about what the engine likes. All I see is 3 paragraphs of useless info that nobody can use because nobody is going to tune their engine based on any of it.
04-03-2018, 10:09 AM
#46
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Injector Tech Hi CD/King, good tech and the fact that all are in basic AGREEMENT. (GREAT INJECTOR TECH THREAD)
WE all have different ways of stating tech, many here ask me for a better explanation = OK.
NOW some simple corrections :
POOR combustion = Rich (below stoic) AFR AND reads Lean as you state when viewed by a EGO sensor.
EOIT is your good tech, I will add the fact that the injectors "open/start of fuel flow" ARE different for each fitted injector/runner position.
My 390*-450* Injection Instant is at "0" RPM for the reference, then my ECU Advances the as is the Ignition Timing for RPM/transport delay/injector dead time. (centered around port air flow max speed)
THUS almost the same tech is reported with exception.
EOIT = End OF INJECTION TIMING
Injection Instant = Start OF INJECTION TIMING
METHOD to FIND Injection Timing Setting:
Pick an engine RPM, then fix that AMOUNT with a known throttle Value. (TPS Voltage read)
FIND the point of MAX RPM/MOST FUEL burned by adjustment of Injection Timing.
My ECU-882C does this object setting in an instant, not sure about the GM PCM.
Could others provide a method of Injection Timing Change when GM ECU's are fitted ?
Lance
WE all have different ways of stating tech, many here ask me for a better explanation = OK.
NOW some simple corrections :
POOR combustion = Rich (below stoic) AFR AND reads Lean as you state when viewed by a EGO sensor.
EOIT is your good tech, I will add the fact that the injectors "open/start of fuel flow" ARE different for each fitted injector/runner position.
My 390*-450* Injection Instant is at "0" RPM for the reference, then my ECU Advances the as is the Ignition Timing for RPM/transport delay/injector dead time. (centered around port air flow max speed)
THUS almost the same tech is reported with exception.
EOIT = End OF INJECTION TIMING
Injection Instant = Start OF INJECTION TIMING
METHOD to FIND Injection Timing Setting:
Pick an engine RPM, then fix that AMOUNT with a known throttle Value. (TPS Voltage read)
FIND the point of MAX RPM/MOST FUEL burned by adjustment of Injection Timing.
My ECU-882C does this object setting in an instant, not sure about the GM PCM.
Could others provide a method of Injection Timing Change when GM ECU's are fitted ?
Lance
04-03-2018, 11:41 AM
#47
TECH Fanatic
I suppose I can throw in some GM injector information for Gen III PCM's.
The formula for the GM PCM is in reference periods. There are 8, and goes by 90*, thus 720* cycle. Stock injection timing for many GM (gen III) is 300.5*. It's is calculated using:
Normal + boundary * 90 - 784
Stock boundary is 6.5, and normal table is 5.55. Using these you'll get:
6.5 + 5.55 = 12.05
12.05 * 90 = 1084.5
1084.5 - 784 = 300.5*
300.5 means that the piston is just past BDC on the exhaust stroke, intake valve fully closed (stock cam, most cams). The fuel will sit there and boil off before the valve opens. This is where transient fuel settings become important, such as fuel to wall impact factor and boil time.
360* is TDC between valve events. If there's overlap, it will be on either side of this number as both valves are open.
There is no adjustment on a gen III for rpm or anything else. The EOIT is a single value. I recommend around 360-380* for EOIT on a GM LS. Farther than that seems to cause more problems than it solves. The main issue is simply the raw fuel smell you'll have with no cats and really any amount of overlap, because the fuel will escape into the exhaust as both valves are open. Meanwhile, you can still be reading lean on the W/B because fresh air also makes it into the exhaust, aka, false lean.
GEN IV GM PCM/ECM's do use RPM, so EOIT is more easily calculated using a spreadsheet. I have one I can post later if someone needs it, or they can PM me. I'm on my phone right now.
The formula for the GM PCM is in reference periods. There are 8, and goes by 90*, thus 720* cycle. Stock injection timing for many GM (gen III) is 300.5*. It's is calculated using:
Normal + boundary * 90 - 784
Stock boundary is 6.5, and normal table is 5.55. Using these you'll get:
6.5 + 5.55 = 12.05
12.05 * 90 = 1084.5
1084.5 - 784 = 300.5*
300.5 means that the piston is just past BDC on the exhaust stroke, intake valve fully closed (stock cam, most cams). The fuel will sit there and boil off before the valve opens. This is where transient fuel settings become important, such as fuel to wall impact factor and boil time.
360* is TDC between valve events. If there's overlap, it will be on either side of this number as both valves are open.
There is no adjustment on a gen III for rpm or anything else. The EOIT is a single value. I recommend around 360-380* for EOIT on a GM LS. Farther than that seems to cause more problems than it solves. The main issue is simply the raw fuel smell you'll have with no cats and really any amount of overlap, because the fuel will escape into the exhaust as both valves are open. Meanwhile, you can still be reading lean on the W/B because fresh air also makes it into the exhaust, aka, false lean.
GEN IV GM PCM/ECM's do use RPM, so EOIT is more easily calculated using a spreadsheet. I have one I can post later if someone needs it, or they can PM me. I'm on my phone right now.
04-05-2018, 02:09 PM
#49
TECH Fanatic
0/720 (same thing) to 180 = power stroke
180 to 360 = exhaust
360 to 540 = intake
540 to 720/0 = compression
This is based on the GM PCM programming
360 = TDC between valve events
04-06-2018, 08:40 AM
#50
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Engine Invention/Inventor = 0 Ignition Event Hi CD, I too agree with "0" of the start of the 720 Cycle.
When I invented the DIS ignition for GM in the 1980's (Buick) the SAME question was posed.
"Should we use the Otto Cycle "0" tech for Start of Inducted Air, the Start of the Cycle in degrees" ?
MY ANSWER was NO, my REASON was that HE (Otto) was NOT the inventor of the engine as the FIRST engine was a TWO STROKE !
Bill, the GM project engineer AGREED.
Lance
When I invented the DIS ignition for GM in the 1980's (Buick) the SAME question was posed.
"Should we use the Otto Cycle "0" tech for Start of Inducted Air, the Start of the Cycle in degrees" ?
MY ANSWER was NO, my REASON was that HE (Otto) was NOT the inventor of the engine as the FIRST engine was a TWO STROKE !
Bill, the GM project engineer AGREED.
Lance
04-06-2018, 06:50 PM
#51
TECH Senior Member
04-06-2018, 06:58 PM
#52
TECH Senior Member
For GM there exists an 0411-compatible PCM emulator called Roadrunner made by Moates...
it uses Tunercat or EFILive to edit tables while engine is running...
effects are observable in real-time.
04-07-2018, 10:18 AM
#53
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Tuner Pro RT Hi Joe, great tech, I know Craig, use Tuner Pro RT, Great Products that ALWAYS work well for my needs. (USPS LLV S-10)
Would there be a LS-1 tech member who would like to "find" the best Injection Instant, then report ?
I could help with test procedure.
The Tuner Pro is a LOW COST (almost free) application used to tune some GM PCM.
The RoadRunner costs more but works MUCH Better than HP Tuners, Moates "tech" support is First Class.
I sell Moates Products with discount given to LS-1 Tech Members ?
Lance
Would there be a LS-1 tech member who would like to "find" the best Injection Instant, then report ?
I could help with test procedure.
The Tuner Pro is a LOW COST (almost free) application used to tune some GM PCM.
The RoadRunner costs more but works MUCH Better than HP Tuners, Moates "tech" support is First Class.
I sell Moates Products with discount given to LS-1 Tech Members ?
Lance
04-09-2018, 11:52 AM
#55
I suppose I can throw in some GM injector information for Gen III PCM's.
The formula for the GM PCM is in reference periods. There are 8, and goes by 90*, thus 720* cycle. Stock injection timing for many GM (gen III) is 300.5*. It's is calculated using:
Normal + boundary * 90 - 784
Stock boundary is 6.5, and normal table is 5.55. Using these you'll get:
6.5 + 5.55 = 12.05
12.05 * 90 = 1084.5
1084.5 - 784 = 300.5*
300.5 means that the piston is just past BDC on the exhaust stroke, intake valve fully closed (stock cam, most cams). The fuel will sit there and boil off before the valve opens. This is where transient fuel settings become important, such as fuel to wall impact factor and boil time.
360* is TDC between valve events. If there's overlap, it will be on either side of this number as both valves are open.
There is no adjustment on a gen III for rpm or anything else. The EOIT is a single value. I recommend around 360-380* for EOIT on a GM LS. Farther than that seems to cause more problems than it solves. The main issue is simply the raw fuel smell you'll have with no cats and really any amount of overlap, because the fuel will escape into the exhaust as both valves are open. Meanwhile, you can still be reading lean on the W/B because fresh air also makes it into the exhaust, aka, false lean.
GEN IV GM PCM/ECM's do use RPM, so EOIT is more easily calculated using a spreadsheet. I have one I can post later if someone needs it, or they can PM me. I'm on my phone right now.
The formula for the GM PCM is in reference periods. There are 8, and goes by 90*, thus 720* cycle. Stock injection timing for many GM (gen III) is 300.5*. It's is calculated using:
Normal + boundary * 90 - 784
Stock boundary is 6.5, and normal table is 5.55. Using these you'll get:
6.5 + 5.55 = 12.05
12.05 * 90 = 1084.5
1084.5 - 784 = 300.5*
300.5 means that the piston is just past BDC on the exhaust stroke, intake valve fully closed (stock cam, most cams). The fuel will sit there and boil off before the valve opens. This is where transient fuel settings become important, such as fuel to wall impact factor and boil time.
360* is TDC between valve events. If there's overlap, it will be on either side of this number as both valves are open.
There is no adjustment on a gen III for rpm or anything else. The EOIT is a single value. I recommend around 360-380* for EOIT on a GM LS. Farther than that seems to cause more problems than it solves. The main issue is simply the raw fuel smell you'll have with no cats and really any amount of overlap, because the fuel will escape into the exhaust as both valves are open. Meanwhile, you can still be reading lean on the W/B because fresh air also makes it into the exhaust, aka, false lean.
GEN IV GM PCM/ECM's do use RPM, so EOIT is more easily calculated using a spreadsheet. I have one I can post later if someone needs it, or they can PM me. I'm on my phone right now.
theres a great thread on hptuner about this also I want to post but I cant remember