Cannot figure out this idle problem

Ross

Goblin Guru
Nice find. I see you are getting KR (engine Knock, Retard the spark timing) everytime you use the throttle.
Not sure if your knock sensor needs to be calibrated and it is giving you phantom knock or if it is real knock.
Is it running on low octane fuel? How old is the fuel?

The knock sensor is below the oil filter.
Did you touch the knock sensor? It is suppose to have the wires leaving the sensor at the 9 oclock position, and be torqued to 18 ft lbs.
I can't find a "Chevy" way to recalibrate the knock sensor... but HP Tuners allows changes. Post #16 here.
 
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Keckster

Well-Known Member
It's on 93 filled up yesterday. The knock is happing at strange points. It only seems to be when I first step of the gas from low speed. I can physically feel the car bogging down. I'm not sure I can tell you if I can feel it knock or if it is phantom knock. I do have my balance shafts deleted so not sure if that can trigger the knock sensor. Drove to and from autozone and the knock is in the log every time I'm shifting or pulling out from a stop.
 

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Keckster

Well-Known Member
Did you touch the knock sensor? It is suppose to have the wires leaving the sensor at the 9 oclock position, and be torqued to 18 ft lbs.
Man you know your stuff! Yeah my knock sensor is facing the wrong way. strange I haven't gotten knock till now from it being wrong
 

Keckster

Well-Known Member
Rotated the knock sensor and still getting the knock. It only occurs when you kick the throttle though. I'm gonna be doing VE and spark tuning later this week so I'll keep updating on progress. I have 1 step colder plugs, might be the cause of the low end knock. I'll grab some stocks this week to try too
 
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Keckster

Well-Known Member
Fedex delayed the delivery of my replacement wideband again but had to run to the part store for a part for the daily... Took some logs on the way there and back. When browsing through the forums I came across a post by @ctuinstra about disabling traction control. I noticed the knock retard I was getting was right at the start of me jabbing the throttle. After disabling traction control I no longer get that knock retard at initial tip in. The car is still kind of lazy pulling out from a stop but I believe that is just due to more tuning time being needed. The car still drops rpm pretty low when coming to a stop but it does catch itself and start idling smoothly pretty quickly now! Thanks for all the help you guys provided!
 

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Joebob

Goblin Guru
What I can see without the wideband in place is by looking at your logs, it still looks to me like your injectors are too large. You have periods of light cruise in which you are at your minimum .6ms pulse and 1.1% duty cycle, yet you are still running 10% rich and the ECU can't cycle the mixture to cycle the O2 sensor for long stretches of time. I think the stumble is that it can't go lower in the pulse width a stubles to have a good mixture under no load. Until you are running near 50mph, your injector pulse raises to 1.1-1.3ms and yhe O2 sensor starts working to hold stoic. and starting to more accurately adjust LTFT so that STFT can cycle near 0.
 

Keckster

Well-Known Member
What I can see without the wideband in place is by looking at your logs, it still looks to me like your injectors are too large. You have periods of light cruise in which you are at your minimum .6ms pulse and 1.1% duty cycle, yet you are still running 10% rich and the ECU can't cycle the mixture to cycle the O2 sensor for long stretches of time. I think the stumble is that it can't go lower in the pulse width a stubles to have a good mixture under no load. Until you are running near 50mph, your injector pulse raises to 1.1-1.3ms and yhe O2 sensor starts working to hold stoic. and starting to more accurately adjust LTFT so that STFT can cycle near 0.
Do you think adding on a boost reference fuel pressure regulator would help with this? I’ve been planning on getting one but haven’t pulled the trigger yet
 

Joebob

Goblin Guru
Before slapping parts on or changing it out, I would get the wideband running to geta clearer picture, A Boost referenced system should help idle as it should lower the fuel rail pressure at high vacuum which should force a longer injector pulse for a given fuel mass desired. The issie is how much it lowers at high vacuum vs just raising presure for high boost events. I don't know enough so say.

Joe
 

Ross

Goblin Guru
Yes, a boost reference fuel regulator would reduce the fuel pressure at idle, giving your engine less fuel when the injectors are at their minimum pulse, but still gives your engine full fuel pressure when it is at high boost, and the injectors are at the high pulse width.
Basically a BRFR gives the injectors more fuel range.

Wait... your tuning without a wideband O2... sketchy. You need the wideband to tell the truth about how the engine is running.
 

Keckster

Well-Known Member
FedEx just delivered the new wideband. I’ll get it installed right away. Unfortunately it just started raining and is supposed to for the rest of the day so I guess my next log won’t be until tomorrow
 

Keckster

Well-Known Member
Yes, a boost reference fuel regulator would reduce the fuel pressure at idle, giving your engine less fuel when the injectors are at their minimum pulse, but still gives your engine full fuel pressure when it is at high boost, and the injectors are at the high pulse width.
Basically a BRFR gives the injectors more fuel range.

Wait... your tuning without a wideband O2... sketchy. You need the wideband to tell the truth about how the engine is running.
I had a wideband when I first started tuning. I went to autox and got rained on which killed the wideband controller. Be waiting on everything on back order for about a month now…
 

Gtstorey

Goblin Guru
What's the injector duty cycle at wide open throttle? You might get by with just a lower base fuel pressure.
 

Ross

Goblin Guru
You fixed the KR issue, but I see you are getting heat soak (high intake air temperatures).
Your laminova cores in the intercooler are keeping up the cooling? Your intercooler water pump isn't pumping? (Common issue)
 

Keckster

Well-Known Member
You fixed the KR issue, but I see you are getting heat soak (high intake air temperatures).
Your laminova cores in the intercooler are keeping up the cooling? Your intercooler water pump isn't pumping? (Common issue)
Pump does work and pumps the correct direction. I do have a small leak up at the HE so there might be air in the system
 

ctuinstra

Goblin Guru
What I can see without the wideband in place is by looking at your logs, it still looks to me like your injectors are too large. You have periods of light cruise in which you are at your minimum .6ms pulse and 1.1% duty cycle, yet you are still running 10% rich and the ECU can't cycle the mixture to cycle the O2 sensor for long stretches of time. I think the stumble is that it can't go lower in the pulse width a stubles to have a good mixture under no load. Until you are running near 50mph, your injector pulse raises to 1.1-1.3ms and yhe O2 sensor starts working to hold stoic. and starting to more accurately adjust LTFT so that STFT can cycle near 0.
I noticed the same thing. I'm not a fan of the huge injectors for that reason. I didn't know if he was planning on running E85, in which he may need those. For some reason everyone believes that they have to have these massive injectors after installing a few mods (not aimed at the op here, just tuners in general). They just ruin the idle.

Looking at the limited log data, at 181 kPa MAP, the injectors are at only 31.7%. That's a lot of headroom.
 

ctuinstra

Goblin Guru
Before slapping parts on or changing it out, I would get the wideband running to geta clearer picture, A Boost referenced system should help idle as it should lower the fuel rail pressure at high vacuum which should force a longer injector pulse for a given fuel mass desired. The issie is how much it lowers at high vacuum vs just raising presure for high boost events. I don't know enough so say.

Joe
This is true, the BRFS will lower the fuel pressure at idle, causing the injectors to have to have longer pulses, but it's not a miracle cure, but it will help. I do have this system set up and I like it a lot!

It can be adjusted to suit your target pressure. Ideally it's normally set at atmosphere to the bar desired.
 

Keckster

Well-Known Member
E85 is a future goal but I want o have a solid pump tune setup first. I was aware of the poor idle issue with the larger injectors before. The main issue I started this thread for was a very poor idle and failure to catch idle on coastdown ending with stalls. I had some Siemens #60 injectors before these #80 but I had even harder time getting it to idle due to the spray pattern not being split like the stock. Just finished installing the new wideband so if the weather clears up tomorrow I’ll hopefully be able to make some good progress
 

ctuinstra

Goblin Guru
Was it that hot out today? IAT1 of 106?! Man, that's too hot for me to ride. Unless you are in the desert.

IAT1 of 106 and IAT2 of 130 isn't terrible.


But your LTFT are all over the place now and is screaming for a good tune. Hopefully you can get the AFR set up and get to tuning. If you tune in hot weather, it's not a bad idea to re-tune later when the weather is more inline with when you normally drive it. The density altitude is probably way off right now.
 
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Keckster

Well-Known Member
Was it that hot out today? IAT1 of 106?! Man, that's too hot for me to ride. Unless you are in the desert.

IAT1 of 106 and IAT2 of 130 isn't terrible.


But your LTFT are all over the place now and is screaming for a good tune. Hopefully you can get the AFR set up and get to tuning. If you tune in hot weather, it's not a bad idea to re-tune later when the weather is more inline with when you normally drive it. The air density is probably way off right now.
No yesterday wasn't that hot, Only got to a high of 80 when I was out driving. However, I haven't thought about it but my oil cooler might be heating up the intake. I'll go switch the rotation of the fan and see if it makes a difference
 

ctuinstra

Goblin Guru
No yesterday wasn't that hot, Only got to a high of 80 when I was out driving. However, I haven't thought about it but my oil cooler might be heating up the intake. I'll go switch the rotation of the fan and see if it makes a difference
It was available in your logging data. It's not uncommon to see the IAT1 just a bit higher than ambient. 20 degrees higher is odd. The sensor is part of you MAF, so it's being measured at your MAF location.

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