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Author Topic: Excessive wall wetting causing extreme idle surging  (Read 966 times)
joshuafarwel
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« on: July 01, 2022, 09:59:19 PM »

Im using some decapped flex fuel LS injectors that work great aside from i cant for the life of me get the idle to not surge. ive actually tried for like a year to get a non-surging idle from different injectors and the only injectors i can use are stock or the green giant 440s but i need at least 80lb injectors. i know how dumb i sound for not just buying injectors with an approved spray pattern but im pretty sure any 100lb injector will have lots of wall wetting and im broke.

i need ideas. ive tried hundreds of combinations with the throttle pid, kfmres, kfzw, kfzwop, wall wetting maps, forcing the timing to be limited to a small amount of advance/retard, tried zeroing out the throttle pid, tried zeroing the wall wetting maps, tried high rpm idle, and the opposite of those things and everything inbetween. im not giving up just yet since i know my injectors are mint. theres gotta be a way to get it to not constantly overshoot and overcompensate for it constantly. itd be even better if ive just been overlooking something super obvious and basic.

also i just saw this screen shot a sec ago and it makes no sense. the rpm surges but the throttle is static, and the injector pulsewidth is barely moving around in any specific direction that correlates with the rpm surging.
bouta get a stand alone and a cable throttle, someone help me.
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prj
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« Reply #1 on: July 02, 2022, 01:06:52 AM »

Injectors have nothing to do with it.
You either have one cylinder not firing half the time or you fucked up the vacuum system.
« Last Edit: July 02, 2022, 01:08:49 AM by prj » Logged

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_nameless
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« Reply #2 on: July 02, 2022, 07:35:42 AM »

Im using some decapped flex fuel LS injectors that work great aside from i cant for the life of me get the idle to not surge. ive actually tried for like a year to get a non-surging idle from different injectors and the only injectors i can use are stock or the green giant 440s but i need at least 80lb injectors. i know how dumb i sound for not just buying injectors with an approved spray pattern but im pretty sure any 100lb injector will have lots of wall wetting and im broke.

i need ideas. ive tried hundreds of combinations with the throttle pid, kfmres, kfzw, kfzwop, wall wetting maps, forcing the timing to be limited to a small amount of advance/retard, tried zeroing out the throttle pid, tried zeroing the wall wetting maps, tried high rpm idle, and the opposite of those things and everything inbetween. im not giving up just yet since i know my injectors are mint. theres gotta be a way to get it to not constantly overshoot and overcompensate for it constantly. itd be even better if ive just been overlooking something super obvious and basic.

also i just saw this screen shot a sec ago and it makes no sense. the rpm surges but the throttle is static, and the injector pulsewidth is barely moving around in any specific direction that correlates with the rpm surging.
bouta get a stand alone and a cable throttle, someone help me.
I use these all the time on +400hp applications without any issue. What are you using for dead times? Stock truck dead times from hpt or efi live are not going to be correct after they are decapped and will require a bit of fine tuning.
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_nameless
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« Reply #3 on: July 02, 2022, 07:38:21 AM »

Also for what its worth compression test the engine and pressure test the intake to verify you dont have any hardware faults 
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joshuafarwel
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« Reply #4 on: July 02, 2022, 01:19:33 PM »

Injectors have nothing to do with it.
You either have one cylinder not firing half the time or you fucked up the vacuum system.

Manifold and intakes all sealed off while i tune to eliminate that variable. My injector harness is pretty hacked up and i planned to replace it so maybe that could have something to do with it although i dont get any misfires even when i idle it at 18:1 afr. Sometimes it smooths out and idles super smooth but if i blip the throttle it goes right back to surging up and down. My neighbors hate me
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joshuafarwel
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« Reply #5 on: July 02, 2022, 01:36:19 PM »

I use these all the time on +400hp applications without any issue. What are you using for dead times? Stock truck dead times from hpt or efi live are not going to be correct after they are decapped and will require a bit of fine tuning.

I found the stock dead times for them and used prj's guide to get it as close as i could and im pretty sure ive got it close, but id like to see your numbers to give them a try.
Heres why i think its a wall wetting issue.
If you look at the logs as the rpm is dropping, the pulsewidth goes up and ignition advances to stop the rpm from dropping but lambda doesnt drop until 1 full second after the pulsewidth rises, which makes the rpm overshoot on recovery because the fuel from 1 second prior is now evaporating off the manifolds walls. Even though the ignition goes full retard and the injector pulsewidth drops the rpm keeps rising past the idle rpm target. The process then repeats in reverse, and then that full cycle just goes on forever, only sometimes it levels out and the rpm stays steady.

Ive limited the ignition to only retard to 10° to see if it fixes things but when i think about it having the ignition having the maximum amount of control will probably help me out, so i think ill put that back to stock. Currently i have kfzwop idle numbers in my kfzw for purpose of letting ignition control the idle even when the in-cylinder mixture is always the opposite of what it injects lmao.
« Last Edit: July 02, 2022, 01:41:09 PM by joshuafarwel » Logged
prj
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« Reply #6 on: July 02, 2022, 01:38:28 PM »

You are completely wrong.
It's not a diesel. Fuel is not what makes power. Air does.

Set everything to stock apart from injection constant, fkkvs and tvub.
You don't understand how the engine works or the ECU works and you're making wild guesses and random adjustments.
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joshuafarwel
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« Reply #7 on: July 02, 2022, 02:15:04 PM »

You are completely wrong.
It's not a diesel. Fuel is not what makes power. Air does.

Set everything to stock apart from injection constant, fkkvs and tvub.
You don't understand how the engine works or the ECU works and you're making wild guesses and random adjustments.

Ive tried setting everything to stock and fkkvs to 1. You are right that with a stock file, only having adjustments for 4 bar map, krkte, tvub, and fkkvs to 1s my idle was better but as it warmed up idle started to go up and down more and more until my neighbors were ready to shoot me. The crazy thing is if i go right back to stock injectors the problem disappears. For the longest time i couldnt figure out why tf this happened and the last thing i thought it couldve been is the injectors. It does the same thing in my other car with these injectors. When i use my 630cc dekas i have the exact same issue even on a stock file with only krkte adjusted.

Ill flash a stock file again and try my new tvub and connect a stock map sensor.
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prj
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« Reply #8 on: July 02, 2022, 03:29:14 PM »

You realize the ECU can't even read your 4 bar pressure sensor beyond 2.5 bar range (it does not have a MAP sensor) without a 5120 mod?
If you have a 5120 mod in there, take it out as well.

Also your ignition looks wrong. It shouldn't have 10+ deg just idling. Especially not if you have a light flywheel. Do you have a lighter flywheel than stock?
Did you also mess with KFMIOP/KFMIRL? Set those all to stock.

Also no MAF connected, what's going on?
If you don't have one, then LOL good luck.
« Last Edit: July 02, 2022, 03:39:27 PM by prj » Logged

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joshuafarwel
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« Reply #9 on: July 02, 2022, 04:18:50 PM »

You realize the ECU can't even read your 4 bar pressure sensor beyond 2.5 bar range (it does not have a MAP sensor) without a 5120 mod?
If you have a 5120 mod in there, take it out as well.

Also your ignition looks wrong. It shouldn't have 10+ deg just idling. Especially not if you have a light flywheel. Do you have a lighter flywheel than stock?
Did you also mess with KFMIOP/KFMIRL? Set those all to stock.

Also no MAF connected, what's going on?
If you don't have one, then LOL good luck.

I realize that the map sensor reading probably has nothing to do with it but just for the sake of having the tune match my hardware i set the dslofs and dslgrad to match while testing idle with a stock file. Ill just connect a stock map this time with a stock file just so thats not another variable to throw anything off.
The bin im using is 5120'd and works good for everything except idle but i dont think its the 5120 causing the issues.

Kfmiop and irl are stock for all low loads.

The ignition needs more advance to make up for the torque i lose running low loads at 18:1, and no, theres no difference in my idle surging issue running it at stoich, in fact it seems a lot better the leaner i go, probably because it requires more throttle opening but idk. I understand i should change everything back to stock until i have this sorted then do 1 thing at a time but its time consuming as fuck to edit and flash my car after every small change i make since theres like 50 maps to change. I guess thats what i might have to do though

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prj
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« Reply #10 on: July 03, 2022, 02:51:33 AM »

Remove the 5120!
Take a completely stock file. You can adjust the DSLGRAD and DSLOFS for your 4 bar pressure sensor if thats needed, this won't cause any issues.
Once again, it's not a MAP sensor, these cars don't have one.

Doesn't help that you're running in limp mode on alpha / n map without a MAF.

Do one thing at a time.
You didn't answer about flywheel either.

If this is time consuming bring it to a professional and pay them money to do it. That's what you are paying for.
Nobody on here cares about your moaning about how it's time consuming and about how your neighbours hate you or whatever.
Literally we don't give a shit, so keep it to yourself and talk about things that are relevant.
« Last Edit: July 03, 2022, 02:53:22 AM by prj » Logged

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joshuafarwel
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« Reply #11 on: July 03, 2022, 10:08:58 AM »

Remove the 5120!
Take a completely stock file. You can adjust the DSLGRAD and DSLOFS for your 4 bar pressure sensor if thats needed, this won't cause any issues.
Once again, it's not a MAP sensor, these cars don't have one.

Doesn't help that you're running in limp mode on alpha / n map without a MAF.

Do one thing at a time.
You didn't answer about flywheel either.

If this is time consuming bring it to a professional and pay them money to do it. That's what you are paying for.
Nobody on here cares about your moaning about how it's time consuming and about how your neighbours hate you or whatever.
Literally we don't give a shit, so keep it to yourself and talk about things that are relevant.

Its a stock flywheel, but on my other 1.8t with a lightweight flywheel its definitely worse but ill keep in mind to use more kfmres for that car.
My cars have always managed to have a more steady idle with no maf so i didnt think thatd be the issue. I do have a maf and the file is scaled for it, but i dont have the necessary plumbing to hook it up yet lol but i can get that done just to eliminate that as a  possible factor.
Im going to go back to a stock file for the 3rd time, install my maf, and just focus on getting tvub correct then idle steady before i do anything else. I appreciate you taking your time to set me straight, im too scatter-brained for this stuff and need some guidance sometimes.
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_nameless
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« Reply #12 on: July 03, 2022, 11:39:26 AM »


Im going to go back to a stock file for the 3rd time, install my maf, and just focus on getting tvub correct then idle steady before i do anything else.

I just had a quick look and these are the values im using for tvub  Grin @4 bar base fuel pressure.

Krkte is  Grin but that is for e85, 4 bar charge pressure sensor and no maf and 5120  
« Last Edit: July 08, 2022, 04:34:33 AM by _nameless » Logged

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prj
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« Reply #13 on: July 03, 2022, 01:50:42 PM »

Log looks mega weird to me, so I am thinking there can be some stupid stuff like 5120 not done right or some problem with torque maps.
Hence me saying to put it all to stock and just do the injectors.

Timing is a bit too far forward, I would reduce the advance.
Also at low RPM I wouldn't advance timing on E85, E85 actually burns quicker, it might be going past MBT.

So yeah, use a completely stock file. No bullshit like 5120 or other things, nothing at all.
None of that is required to get the injectors to work and for it to idle right. And if there's a mistake anywhere you're gonna be chasing your tail forever.
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joshuafarwel
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« Reply #14 on: July 03, 2022, 05:45:16 PM »

Log looks mega weird to me, so I am thinking there can be some stupid stuff like 5120 not done right or some problem with torque maps.
Hence me saying to put it all to stock and just do the injectors.

Timing is a bit too far forward, I would reduce the advance.
Also at low RPM I wouldn't advance timing on E85, E85 actually burns quicker, it might be going past MBT.

So yeah, use a completely stock file. No bullshit like 5120 or other things, nothing at all.
None of that is required to get the injectors to work and for it to idle right. And if there's a mistake anywhere you're gonna be chasing your tail forever.


Im going to end up sticking with stock kfzw for idle range. My timings so advanced because im doing the lean burn in vacuum thing. i have dzwola set to 0 (to avoid adding onto kfdzwkg) and kfdzwkg set so 1.2 lambda is advanced 4.5 degrees which is what most studies found was the additional advance required for mbt on e85, i have the richer lambdas in kfdzwkg set according to what i found in studies for e85 too which i think is the proper way to do it. i have kfzw set to kfzwop -1.5degree because e85 burns about that much faster at lambda 1.

heres my most recent log from a couple days ago, idle was decently smooth for the majority of it but after i stopped the log i was on the phone with my gf and told her how well its idling so i blipped the throttle and it went back to its bullshit bouncing up and down
« Last Edit: July 03, 2022, 06:58:27 PM by joshuafarwel » Logged
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