turbo 4.8 idles pig rich cannot adjust
04-17-2016, 10:47 PM
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turbo 4.8 idles pig rich cannot adjust Hi guys, ive already posted this on the hptuners forum but i havent had any luck there, so im hoping perhaps you guys might have a better idea as to whats going on with my tune.
build is simple, 76mm turbo 4.8 stock internals with 317 heads, ls2 cam and aluminum intake manifold off ebay. 80lb deka IV injectors 2 bar map. tuned with hptuners speed density only OS installed.
My issue is that the engine idles pig rich below 10:1 on the PLX afr gauge. the afr gauge is reading correctly, and the offset is within a tenth of what it reads in the logs so its almost dead on with the scanner. Ive attempted to zero out the ve table in the idle sections, with no result as if it switches from the ve table at idle to another table somewhere in the tune. ive tried zeroing afterstart enrichment, p/n enrichment, increasing/decreasing idle airflow and all kinds of combinations of fuel injector minimum's including zeroing out all injector tables.
the only thing ive found that changes the idle injector PW is to flatline the IFR tables at 80lb/h and increase the voltage offset across the board to 1.5 which then gives me a flow rating of around 110lb/h but even then it only idles at 11.5 AFR and runs super lean around the rest of the ve table.
What really surpised me was when i zeroed the ve table and the engine still started and idled at 10:1, like nothing had happened. im really confused and frustrated after almost two weeks of flashing every 30 seconds because RTT is not working in 3.0. Thankyou for the input.
build is simple, 76mm turbo 4.8 stock internals with 317 heads, ls2 cam and aluminum intake manifold off ebay. 80lb deka IV injectors 2 bar map. tuned with hptuners speed density only OS installed.
My issue is that the engine idles pig rich below 10:1 on the PLX afr gauge. the afr gauge is reading correctly, and the offset is within a tenth of what it reads in the logs so its almost dead on with the scanner. Ive attempted to zero out the ve table in the idle sections, with no result as if it switches from the ve table at idle to another table somewhere in the tune. ive tried zeroing afterstart enrichment, p/n enrichment, increasing/decreasing idle airflow and all kinds of combinations of fuel injector minimum's including zeroing out all injector tables.
the only thing ive found that changes the idle injector PW is to flatline the IFR tables at 80lb/h and increase the voltage offset across the board to 1.5 which then gives me a flow rating of around 110lb/h but even then it only idles at 11.5 AFR and runs super lean around the rest of the ve table.
What really surpised me was when i zeroed the ve table and the engine still started and idled at 10:1, like nothing had happened. im really confused and frustrated after almost two weeks of flashing every 30 seconds because RTT is not working in 3.0. Thankyou for the input.
04-18-2016, 05:06 AM
#4
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turbo 4.8 idles pig rich cannot adjust Does the MAP sensor work properly...?
Check what it reads at BARO, and use a vacuum pump to check its linearity (each 2"Hg is about 1 psi, and each 5 psi is about 33 kPa).
Check what it reads at BARO, and use a vacuum pump to check its linearity (each 2"Hg is about 1 psi, and each 5 psi is about 33 kPa).
04-18-2016, 07:28 AM
#5
What is your base fuel rail pressure? Should be 58 psig
Are you using a boost referenced fuel pressure regulator?
Are you using methanol injection and if so, what mixture and nozzle size?
You have changed a ton of tables. Makes it difficult to analyze the file. I've re-attached a file with good 80 lb/hr Deka flow data. My advice would be to leave this injector flow data alone and then work on the rest of your tune as needed. If it were me I would almost start back with a stock 2001 Silverado 4.8 file and only change the tables necessary to properly recalibrate for your setup. You've currently got a hot mess with that file.
Are you using a boost referenced fuel pressure regulator?
Are you using methanol injection and if so, what mixture and nozzle size?
You have changed a ton of tables. Makes it difficult to analyze the file. I've re-attached a file with good 80 lb/hr Deka flow data. My advice would be to leave this injector flow data alone and then work on the rest of your tune as needed. If it were me I would almost start back with a stock 2001 Silverado 4.8 file and only change the tables necessary to properly recalibrate for your setup. You've currently got a hot mess with that file.
04-18-2016, 12:07 PM
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Originally Posted by chevy406
What is your base fuel rail pressure? Should be 58 psig
Are you using a boost referenced fuel pressure regulator?
Are you using methanol injection and if so, what mixture and nozzle size?
You have changed a ton of tables. Makes it difficult to analyze the file. I've re-attached a file with good 80 lb/hr Deka flow data. My advice would be to leave this injector flow data alone and then work on the rest of your tune as needed. If it were me I would almost start back with a stock 2001 Silverado 4.8 file and only change the tables necessary to properly recalibrate for your setup. You've currently got a hot mess with that file.
Are you using a boost referenced fuel pressure regulator?
Are you using methanol injection and if so, what mixture and nozzle size?
You have changed a ton of tables. Makes it difficult to analyze the file. I've re-attached a file with good 80 lb/hr Deka flow data. My advice would be to leave this injector flow data alone and then work on the rest of your tune as needed. If it were me I would almost start back with a stock 2001 Silverado 4.8 file and only change the tables necessary to properly recalibrate for your setup. You've currently got a hot mess with that file.
Last edited by irrational; 04-18-2016 at 12:32 PM.
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04-18-2016, 05:47 PM
#8
He is having injector settings issues. 80 lb dekas are a little special to idle in small engines.
I tried to help the guy but he wanted to quit and go ms3pro, so I stopped
Problem is not so hard and no real time tuning is needed.
I tried to help the guy but he wanted to quit and go ms3pro, so I stopped
Problem is not so hard and no real time tuning is needed.
04-18-2016, 06:47 PM
#9
When it comes to first starts on a fresh set of new injectors that are much larger than OEM, I always know I want my initial injector pulse around idle to be near 1ms (0.001 seconds). Many injectors will display erratic behavior near/under 1ms (they might open every other event, or not at all on some cylinders, giving misfires) , so be aware you may need to raise the pulse to some 1.25 or even 1.4ms and dial back the fuel pressure to compensate. It is ok to reduce fuel pressure some (10~psi is normally acceptable). You could also raise the idle slightly to help with the low pulse.
Next, it sounds like you cannot see an active real-time MAP display, which tells me than an obvious sensor could be disconnected/not working and you wouldn't be able to see it without the real time sequence of events showing up on the computer.
Next, it sounds like you cannot see an active real-time MAP display, which tells me than an obvious sensor could be disconnected/not working and you wouldn't be able to see it without the real time sequence of events showing up on the computer.
04-18-2016, 07:57 PM
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Im beginning to think this is related to my FPR for some reason, even though my gauge seems to be reading correctly. i have a bosch 044 pump and the pressure bleeds off immediately after the pump turns off. Ive heard that this is both normal and bad as a check valve goes bad in the pumps? i dont see how this would relate to a fuel pressure issue though.
When it comes to first starts on a fresh set of new injectors that are much larger than OEM, I always know I want my initial injector pulse around idle to be near 1ms (0.001 seconds). Many injectors will display erratic behavior near/under 1ms (they might open every other event, or not at all on some cylinders, giving misfires) , so be aware you may need to raise the pulse to some 1.25 or even 1.4ms and dial back the fuel pressure to compensate. It is ok to reduce fuel pressure some (10~psi is normally acceptable). You could also raise the idle slightly to help with the low pulse.
Next, it sounds like you cannot see an active real-time MAP display, which tells me than an obvious sensor could be disconnected/not working and you wouldn't be able to see it without the real time sequence of events showing up on the computer.
Next, it sounds like you cannot see an active real-time MAP display, which tells me than an obvious sensor could be disconnected/not working and you wouldn't be able to see it without the real time sequence of events showing up on the computer.
04-18-2016, 11:54 PM
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So i started from scratch, copied all tables over from the original 4.8 tune into this file that chevy406 gave me. I uploaded the stock ve table and started the engine, and it ran super rich.
Started working my way down from the stock ve table subtracting 10-15 percent each increment. Ended up removing almost 90% from the idle section and about 50% from the entire table. The table is a little lean, but the idle section is extremely rough, misfires run like crap. it generally sounds like it has a cam with alot of overlap but its a stock cam it misses and lopes just like it. the reason i did such a large section the same is because the kpa cell it was idling it was constantly moving up and down dependent on the afr and it was varying far too much to get a consistant idle.
Watching my injector PW ms's i can see them jump from .9 to 2.0-2.2 and back down to .9 almost instantly, im assuming its because of the 1 number difference between the 55kpa to 50kpa 800 rpm cells but im not quite sure.
Am i doing something wrong, or is this what you guys were talking about in the idle tuning? ill also include my stock 4.8 file for you guys to compare. thankyou for your help.
Started working my way down from the stock ve table subtracting 10-15 percent each increment. Ended up removing almost 90% from the idle section and about 50% from the entire table. The table is a little lean, but the idle section is extremely rough, misfires run like crap. it generally sounds like it has a cam with alot of overlap but its a stock cam it misses and lopes just like it. the reason i did such a large section the same is because the kpa cell it was idling it was constantly moving up and down dependent on the afr and it was varying far too much to get a consistant idle.
Watching my injector PW ms's i can see them jump from .9 to 2.0-2.2 and back down to .9 almost instantly, im assuming its because of the 1 number difference between the 55kpa to 50kpa 800 rpm cells but im not quite sure.
Am i doing something wrong, or is this what you guys were talking about in the idle tuning? ill also include my stock 4.8 file for you guys to compare. thankyou for your help.
04-19-2016, 12:10 AM
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In transient fueling, did you ever change the minimum fuel mg? It's .046 stock. With 80 pound injectors, this setting needs to drop to 0.010 or possibly even lower.
This setting is often overlooked when injectors are swapped.
This setting is often overlooked when injectors are swapped.
04-19-2016, 08:58 AM
#13
Changing this value to 0.014 or lower will solve the issue.
The answer is already in the first thread He opened, but what can we do...
04-19-2016, 09:57 AM
#14
I posted data for the 80s in the other thread he asked about data before he started this one.
And yes, you have to change the value to .015 or lower for the injector to pulsewidth down enough to idle.
Those injectors are crap anyway. I'd sell them and get something else.
And yes, you have to change the value to .015 or lower for the injector to pulsewidth down enough to idle.
Those injectors are crap anyway. I'd sell them and get something else.
04-19-2016, 01:26 PM
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I posted data for the 80s in the other thread he asked about data before he started this one.
And yes, you have to change the value to .015 or lower for the injector to pulsewidth down enough to idle.
Those injectors are crap anyway. I'd sell them and get something else.
And yes, you have to change the value to .015 or lower for the injector to pulsewidth down enough to idle.
Those injectors are crap anyway. I'd sell them and get something else.
So what exactly does transient fuel qualifications do? and should i change the fuel to wall impact factor as well?
04-19-2016, 01:41 PM
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Personally I don't recommend touching the other tables. Just that minimum mg
04-19-2016, 02:01 PM
#17
Russ-K told you exactly what to change
Go to Transient Fuel and reduce the Min Fuel milligrams from whatever it has to 0.014 and test. Bring it lower until you gain fuel control with the VE table.
The easy way to know is if you can enrich/enlean the AFR using either the VE table or scanner controls, you are in the ballpark. If you can't change the AFR then you need to lower it more.
I don't like to zero it, since it causes lean stumbles when you press the gas pedal. It can be compensated with VE table but I prefer to use the highest possible setting. For me it goes from 0.018 for 6.0L to 0.004 for 4.8 engines.
Go to Transient Fuel and reduce the Min Fuel milligrams from whatever it has to 0.014 and test. Bring it lower until you gain fuel control with the VE table.
The easy way to know is if you can enrich/enlean the AFR using either the VE table or scanner controls, you are in the ballpark. If you can't change the AFR then you need to lower it more.
I don't like to zero it, since it causes lean stumbles when you press the gas pedal. It can be compensated with VE table but I prefer to use the highest possible setting. For me it goes from 0.018 for 6.0L to 0.004 for 4.8 engines.
04-19-2016, 03:10 PM
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After making that change i can get the idle up to around 14 AFR, but it misfires and stumbles like you guys were saying it would. it only seems to smooth out around 11 AFR. perhaps because my compression ratio is so low i cannot go low enough in pulse width for the amount of fuel i need at idle?
Also, i had to lower my minimum injector pulse ms or else it would not go above 11 even with the fuel mg at 0 and putting 1's on the ve table in the idle section.
I got that lean stumble you were talking about and started tuning it out in the ve table, ill revert the table back and put .004 in instead.
Also, i had to lower my minimum injector pulse ms or else it would not go above 11 even with the fuel mg at 0 and putting 1's on the ve table in the idle section.
I got that lean stumble you were talking about and started tuning it out in the ve table, ill revert the table back and put .004 in instead.
04-19-2016, 03:23 PM
#19
This is from Paul Yaw at ID:
So the point here is to take the min PW and divide by 31.12 and see what that value is. It should be under .020 in the Min Fuel Milligrams table under transient fueling. In fact, you can take an ID injector down to about .008 and it'll still be stable.
But do not just randomly do it. It is tied to the pw of the injector. I'm not sure the 80s can pw down low enough for a 4.8L. But calculated, your value should be .018. Anything below that, and the injector can't stay open properly per Paul's observation "below the knee."
One other thing to mess with is EOIT... see if you can delay it a bit so you burn the fuel you do spray, and then you can command less fuel to get it to lean out.
I chose a value low enough that it would not limit the injector operation [for Min Fuel Milligrams affect on minimum possible PW], based on the assumption that it had no effect on the transient fueling.
From what I see in this thread, it appears that assumption was incorrect.
We might try 5.7 Ute's recommendation of dividing the injectors minimum pulse width value by 31.124308, but then we need to define the injector minimum pulse width more carefully.
A pulse width of .6 msec puts us at the "knee" of the flow vs pulse width curve of the ID2000 at 4 bar differential pressure. Above the knee, the injector output is very stable and repeatable. Below the knee, the valve is not open fully, and the output is less stable and predictable.
The flow at this pulse width is approximately 12 milligrams per shot, and is right at the edge of providing a stoichiometric idle on a 550cc cylinder with a "stock" low overlap cam idling at approximately 35kPa manifold pressure. Any V8 bigger than 4.4L should not need a smaller pulse width to achieve a stoichiometric idle, but you may be pushing it when manifold vacuum is low, like at high rpm with a closed throttle.
Edging below that value of .6 msec gets us into the less desirable range, but that is certainly better than running pig rich.
Using .6 msec as a starting point, we get a value of .020.
If your data logs tell you that .6 msec is not low enough, back it down by the percentage error in your lambda value, and recalculate the transient value using 5.7 Ute's factor of 31.124308.
From what I see in this thread, it appears that assumption was incorrect.
We might try 5.7 Ute's recommendation of dividing the injectors minimum pulse width value by 31.124308, but then we need to define the injector minimum pulse width more carefully.
A pulse width of .6 msec puts us at the "knee" of the flow vs pulse width curve of the ID2000 at 4 bar differential pressure. Above the knee, the injector output is very stable and repeatable. Below the knee, the valve is not open fully, and the output is less stable and predictable.
The flow at this pulse width is approximately 12 milligrams per shot, and is right at the edge of providing a stoichiometric idle on a 550cc cylinder with a "stock" low overlap cam idling at approximately 35kPa manifold pressure. Any V8 bigger than 4.4L should not need a smaller pulse width to achieve a stoichiometric idle, but you may be pushing it when manifold vacuum is low, like at high rpm with a closed throttle.
Edging below that value of .6 msec gets us into the less desirable range, but that is certainly better than running pig rich.
Using .6 msec as a starting point, we get a value of .020.
If your data logs tell you that .6 msec is not low enough, back it down by the percentage error in your lambda value, and recalculate the transient value using 5.7 Ute's factor of 31.124308.
But do not just randomly do it. It is tied to the pw of the injector. I'm not sure the 80s can pw down low enough for a 4.8L. But calculated, your value should be .018. Anything below that, and the injector can't stay open properly per Paul's observation "below the knee."
One other thing to mess with is EOIT... see if you can delay it a bit so you burn the fuel you do spray, and then you can command less fuel to get it to lean out.
04-19-2016, 03:52 PM
#20
The 80's are big for a 4.8 in my opinion. They barely idle at 14 AFR in a 5.3, they are very inconsistent below 1.6 ms PW. If you trick them to lower PW the engine starts to misfire and go very lean. Very small changes in fueling cause big swings in AFR.
So, if you already have them that's OK but don't expect them to idle at 500 RPM and 14.7 AFR in a consistent way. For a race car they are good but not for a daily driver.
So, if you already have them that's OK but don't expect them to idle at 500 RPM and 14.7 AFR in a consistent way. For a race car they are good but not for a daily driver.