Idle issues caused by STFT
Attached are two logs, no changes in tune, DFCO disabled. Cyl fill around .8-.9 Seems like I need to play with the Transient tab a little bit but im not so slick and thats time consuming stuff for me. Still having that hard stop at 1.7-1.8 injector pulse but it didnt act up on me too much
Those are close enough that I wouldn't be worried. Far cry from the difference between 42 and 49... Flow rate isn't really the biggest concern though...much easier to bury that error in somewhere else, even if you absolutely had to deal with the error. The table that will keep causing you problems is the offset. The less fuel you want, the bigger the impact the offsets have. And the error can't be buried elsewhere. So double check all the data, make sure nothing else is amiss.
Okay I will double check but I’m sure I copied the data provided. So say next step would be reducing the offsets? Where would I even start knowing where to go after that. That’s a monster of a table lol
I would not adjust injector data ever. It is a characterized piece of hardware. All of those cal values outside of flow rate represent a compensation for some physical characteristic of the injector...and those don't change. They are essential to linearize the injector's behavior over the full range of operation. If it is indeed the long minimum pulse width that is the root cause of all of your issues (assuming the data was perfect), then the simple answer is you are using the wrong injector. Not all are created equal.
I would not adjust injector data ever. It is a characterized piece of hardware. All of those cal values outside of flow rate represent a compensation for some physical characteristic of the injector...and those don't change. They are essential to linearize the injector's behavior over the full range of operation. If it is indeed the long minimum pulse width that is the root cause of all of your issues (assuming the data was perfect), then the simple answer is you are using the wrong injector. Not all are created equal.
I’m thinking maybe a test of running
FIC’s pulse modifiers as they are rated much lower than what I have, something like .806 on the min and default and the short pulse and adders are less too..
these injectors aren’t THAT big and should easily fire at their minimum pulse I’d think…. Which according to FIC is .8 or something. I think if I could get them down to 1.5 or 1.6 It would lean out. Quite frankly I’d be fine fixing it with VE adjustments but they just bottom out at 1.7-1.8. I have to work the next few days but I will have to try and post my findings on it. If I could get to low 14s AFR on decel I’d be more than happy. As of right now the cars tune is close enough back that the car is driveable. It’s really likely that me being supplied with the wrong data is what made my transients so hard to get in line. Hopefully once I get this issue fixed I can get them fixed again.. I really do appreciate your help with this…either way, do you any particular set of injectors that would you recommend if I had to do this all over again?
I am the last person that would ever blindly recommend the most expensive option ...but you get what you pay for with ID. Having spoken to/worked with Paul and his products as well as being someone who values quality, I don't run anything else in my vehicles. Or any vehicle I work closely with. If you want the fuel you ask for to be the fuel that you get, ID is where you need to shop.
Last edited by smokeshow; Oct 6, 2021 at 10:53 AM.
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Smoke is definitely correct about injector data. The only part I’ve ever tweaked are the minimum pulses for basically the exact problem you are having. The bigger the injector, the more likely this will have to be reduced to correct a rich decel transient.
However, having said that, you also have to make sure the problem isn’t the VE table. I’ve had numbers as low as 10 on the VE and still showed 20% rich after a bunch of reductions. That’s about the only time I will reduce the minimums since the only thing it will affect is decel. Data outside of this needs to be good obviously, and I’ve even talked direct to manufacturers and they even recommended reducing the values for the minimums to correct it. Albeit, those injectors were twice the size as yours.
Anyway, the process is to confirm it’s NOT another table like VE causing it, then make it a SOLE correction as you go and check for results. STFT’s should be off, and any other trims. It should be set to tune VE, aka all adders removed.
That tweak should be the last thing you do to drive the change you want. Why do you think I was hesitant enough to call directly to a manufacturer and ask them years ago? I had reservations about touching the data, but I do know it can fix a rich off throttle if that is the ONLY thing left and the problem isn’t sitting buried in another table somewhere.
If it is indeed the last thing, then yes, it will fix that issue, and your P/W will come down considerably as you adjust. The fact that yours isn’t changing suggests it’s buried on another table.
However, having said that, you also have to make sure the problem isn’t the VE table. I’ve had numbers as low as 10 on the VE and still showed 20% rich after a bunch of reductions. That’s about the only time I will reduce the minimums since the only thing it will affect is decel. Data outside of this needs to be good obviously, and I’ve even talked direct to manufacturers and they even recommended reducing the values for the minimums to correct it. Albeit, those injectors were twice the size as yours.
Anyway, the process is to confirm it’s NOT another table like VE causing it, then make it a SOLE correction as you go and check for results. STFT’s should be off, and any other trims. It should be set to tune VE, aka all adders removed.
That tweak should be the last thing you do to drive the change you want. Why do you think I was hesitant enough to call directly to a manufacturer and ask them years ago? I had reservations about touching the data, but I do know it can fix a rich off throttle if that is the ONLY thing left and the problem isn’t sitting buried in another table somewhere.
If it is indeed the last thing, then yes, it will fix that issue, and your P/W will come down considerably as you adjust. The fact that yours isn’t changing suggests it’s buried on another table.
Okay, is my method of hitting a decel and then manually commanding say 19.0 AFR in the scanner and seeing no change in pulse width or AFR a good indication it isn’t in my VE table and hitting some other limit? It seems it is only in the mid rpm range that it can’t control itself. Below 2000 and it seems to get back in line. It’s not supposed to rain Friday so hopefully I can get back in the car. So you suggest taking pulse widths out of the min and default little by little and watching results? I’d probably go after .100 MS at each time. I have about a 2 mile hill near my house that I can use to log
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Car is a cammed Ls1 m6. Runs great. Did the tuning. Afrs are right where I like them. Only issue that I can’t get rid of is on instances of decel and then coming to a stop. Car has 42 # injectors. Goes rich on decel. DFCO covers most of it. However decel from 60 to a stop, going down through gears. DFCO cuts off in 2nd usually and then the STFTs go way negative cause it’s trying to lean it out but min pulse width won’t go lower. So by the time I stop and idle at 900rpm thw STFTs are both at -32 and it idles at 18-19AFR until they slowly crawl back up above 0. It’s not in the VE map car runs fine in open loop VE, Open loop MAF and Open loop blended. it’s the STFTs themself and idk how to stop this. I’d thought about the hybrid method but my car idles at 70kpa and I don’t think id have enough resolution to my map table. I.E. chugging up my hill in the morning while the car is still chilly doesn’t give me a big enough difference to compensate with open loop idle. I know the real fix is fixing the rich decel. But I’m unsure how to do this. Not wanting to be spoonfed but I’ve tried and tried to fix this. Can someone point me in the direction?
I have sent you a PM with an explanation by Maslic relative to the 'Throttle Follower" table settings." For less than a "twenty' you can download the entire PDF manual.
http://www.masterenginetuner.com/
In short, if throttle delay is not set correctly and delay is too short, engine on decel doesn't have enough time allow any injected fuel to be fully burned off after you have let off the throttle. This results in a rich condition on decel.
FWIW: The dashpot control on carb'd engines accomplished the same thing.
Last edited by dlandsvZ28; Oct 6, 2021 at 09:26 AM. Reason: edit content
OP
I have sent you a PM with an explanation by Maslic relative to the 'Throttle Follower" table settings." For less than a "twenty' you can download the entire PDF manual.
http://www.masterenginetuner.com/
In short, if throttle delay is not set correctly and delay is too short, engine on decel doesn't have enough time allow any injected fuel to be fully burned off after you have let off the throttle. This results in a rich condition on decel.
FWIW: The dashpot control on carb'd engines accomplished the same thing.
I have sent you a PM with an explanation by Maslic relative to the 'Throttle Follower" table settings." For less than a "twenty' you can download the entire PDF manual.
http://www.masterenginetuner.com/
In short, if throttle delay is not set correctly and delay is too short, engine on decel doesn't have enough time allow any injected fuel to be fully burned off after you have let off the throttle. This results in a rich condition on decel.
FWIW: The dashpot control on carb'd engines accomplished the same thing.
Okay, is my method of hitting a decel and then manually commanding say 19.0 AFR in the scanner and seeing no change in pulse width or AFR a good indication it isn’t in my VE table and hitting some other limit? It seems it is only in the mid rpm range that it can’t control itself. Below 2000 and it seems to get back in line. It’s not supposed to rain Friday so hopefully I can get back in the car. So you suggest taking pulse widths out of the min and default little by little and watching results? I’d probably go after .100 MS at each time. I have about a 2 mile hill near my house that I can use to log
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Maslic's tuning guide follows closely the explanations in the link below for Throttle Follower, Throttle Cracker, etc.
https://www.hptuners.com/help/vcm_ed...le_airflow.htm
Pretty much. But the detailed explanation covers 4 to five pages. A quote from the manual "To address exhaust emissions, the Throttle Follower has a “Delay” function. This allows a momentary delay before reducing engine airflow to allow any injected fuel to be fully burned once the driver has closed the throttle."
Maslic's tuning guide follows closely the explanations in the link below for Throttle Follower, Throttle Cracker, etc.
https://www.hptuners.com/help/vcm_ed...le_airflow.htm
Maslic's tuning guide follows closely the explanations in the link below for Throttle Follower, Throttle Cracker, etc.
https://www.hptuners.com/help/vcm_ed...le_airflow.htm
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It is Not my intention to hijack this thread. I read OP's issue as rich meaning that when there is less oxygen compared to fuel after combustion, that this is referred to as a rich mixture or an AFR that is higher than stoic.
After reading these links and a bunch of others I'm beginning to understand the issues the OP is referring to.
https://forum.hptuners.com/showthrea...e-rich-tip-out
https://ls1tech.com/forums/pcm-diagn...l#post20384644
Just a retouch, it’s been raining and generally nasty the past few days. However just from using the RIGHT(I think) data and retuning my fueling tables the issue hasn’t stopped, but it has become MUCH better in regards to how much trimming my STFTs are doing. I’m not seeing 19-20 AFR coming to a stop. It’s more or less around 16.5 which for my car it’s not that bad.
Also, as a side note my throttle hang outside of my weird AC issue was ALL fixed by changing my throttle cracker and the low rpm surging I still have a little but it was made much much better by making my timing all of the same or very small incrementations and generally a smooth transition in those stupid low areas. I fixed my low rpm surging by adjusting the throttle cracker and tinkering with my timing tables… I mean hey my tune is posted. Feel free to have a look lmao. What helped me is to view timing in the 2d line chart. And go find an open parking lot and see what areas you’re bucking in. That made the biggest difference in my bucking bronco issues.
I later fixed my AC causing idle hang by adjust the AC torque settings. At first it would ALWAYS idle hang with ac on. It still tends to hang when I go WOT with ac on or shut off ac during a drive cycle. Idk why. I just think my car was born crosseyed
Also, as a side note my throttle hang outside of my weird AC issue was ALL fixed by changing my throttle cracker and the low rpm surging I still have a little but it was made much much better by making my timing all of the same or very small incrementations and generally a smooth transition in those stupid low areas. I fixed my low rpm surging by adjusting the throttle cracker and tinkering with my timing tables… I mean hey my tune is posted. Feel free to have a look lmao. What helped me is to view timing in the 2d line chart. And go find an open parking lot and see what areas you’re bucking in. That made the biggest difference in my bucking bronco issues.
I later fixed my AC causing idle hang by adjust the AC torque settings. At first it would ALWAYS idle hang with ac on. It still tends to hang when I go WOT with ac on or shut off ac during a drive cycle. Idk why. I just think my car was born crosseyed
Last edited by mstansbury0704; Oct 9, 2021 at 12:02 PM.