Summit 8701r1 gen 3 cam tune

[InandOutPerfromance]

Hello all first time poster and pretty much same when it comes to tuning. Been trying to read and learn and watch as much info as possible before asking for advice. But i think its time i get a little professional opinion. Was hoping i could get some of the more experienced folk to take a look at what ive got so far and maybe some pointers. Truck idles great in park, in gear struggles when stopped at a light(pretty sure i have a leaking brake booster causing lean spikes. kpa's goes way up at idle in gear with heavy braking applied) Biggest issue is truck doesnt really wanna go. Has spots where it feels pretty good and then it hits the wall in others. Anyhow here is tune file and thanks in advance for any help. Its really appreciated!!

[edcmat-l1]

Ya know, it actually ain't awful. You do have it in speed density.

Being a cable T-body, you'll need to get your IAC counts right. That's a mechanical thing. There's plenty of write ups on here.

I added a little idle airflow for you. Should help it but it's not the end all fix. Need to get the IAC counts straight.

[InandOutPerfromance]

Awesome, thank you. I will try and find the write ups on that. Appreciate your time sir!!

[blindsquirrel]

It's normal for the brake booster to 'use' airflow when the pedal is pumped, that's what makes the booster work. Pumping the pedal is actually a quick dirty service bay test to temporarily cause a lean condition, for checking O2 response etc.

[InandOut]

It's normal for the brake booster to 'use' airflow when the pedal is pumped, that's what makes the booster work. Pumping the pedal is actually a quick dirty service bay test to temporarily cause a lean condition, for checking O2 response etc.

Yeah, but this dip is way beyond the considered normal. Truck gets in a shutter that almost isnt recoverable, it bogs real hard and i have to "feather" the pedal until it gets back in the cells over next to it. For whatever reason it digs hard into the 400 region in the table.
Then Kpa's go all the way up to the high 90's and just lugs around there in a studder until i throttle it out. Whats weird is it call for way more fuel there in the log. Then when i make said adjustments it compounds the problem. I'm confused to say the least. For what its worth
this is the only place in the "tune" im having issues. Well i think lol.

[blindsquirrel]

Big(ger) cam with less idle vacuum will show more of an impact. That's part of it.

An easy test is, turn the engine off and wait like 10-15 seconds, then press the brake pedal. Is it rock hard, or is there some vacuum assist still in there? If the booster is leaking there will be absolutely no vacuum in the booster immediately after the engine is shut off.

[InandOut]

Imma check on that in the morning. Also i think imma go for a ride with the log and try and get a snippet of what im trying to explain. I think that will be a whole lot better and save some time to boot. Thank yall for the responses!

[InandOut]

Ya know, it actually ain't awful. You do have it in speed density.

Being a cable T-body, you'll need to get your IAC counts right. That's a mechanical thing. There's plenty of write ups on here.

I added a little idle airflow for you. Should help it but it's not the end all fix. Need to get the IAC counts straight.

Here's my contribution for drive-by-cable engines

I recently had to tame a pair of LS1's this past summer that lead me to learn everything posted above. One LS1 in particular had a cable driven throttle body and the following is what I did to create a rock solid idle. I learned everything I know from HPTuners forum so here's me giving back.

During your engine build, if you have a cable driven throttle body, do yourself a favor and unbolt your throttle body from your intake and use a Torx T15 bit to flip your set screw upside down. From the factory it's only accessible from underneath and it sucks to try to adjust the set screw once the engine is in the vehicle and you've got everything hooked up. By flipping the set screw upside down, you've made it possible to make adjustments to the throttle blade easier.

Once you have the engine idling somewhat ok, use the scanner to verify a few parameters. Look at IAC (idle air control) counts to see if they're in check. Why? The idle air control valve in the throttle body has a max range between 0 and 310 (usually) to attempt at holding your idle right where you command. The idle air control valve (IAC valve from now on) is designed to let by-pass air flow into the engine simply to hold idle steady and it opens/closes depending on if the computer detects the idle falling or getting too high. Most well tuned engines regardless of cam size can make use of the 0-310 range which the IAC valve has but sometimes you have to help it by opening or closing the throttle blade a little.

This is where the idea behind drilling throttle blades comes in. Don't do that yet! Thankfully you read this thread before shoe-horning your LS1 into some tight engine compartment and you flipped your throttle blade set screw over so you can open or close your throttle blade by little increments at a time. Most of us need to open it.

If the IAC counts in the scan are basically stuck at zero no matter what, that means the IAC valve is closed because it's trying to limit how much airflow is being sucked at idle. This either means your throttle body is open too much, or you could potentially have a vacuum leak somewhere and this should be addressed before continuing. Did someone previously drill a hole in your throttle body and now it's getting too much airflow this way? Assuming your seals are in working order and your TB isn't holy () you simply need to close the throttle blade a little bit as long as it doesn't stick shut. You'll know what this feels like when you hit that "stuck" point when the blade is closed all the way - hopefully you don't hit that.

On the flip side, if your IAC counts are maxed at 310 it means your IAC valve is sucking as much air as it's allowed to and that's really the only thing holding your idle somewhat steady. This is where you need to open your throttle blade by adjusting the set screw with the T15 bit. How much? Well...read on. There are a few parameters or "rules" for opening the set screw you should keep in mind, and you'll use the VCM scanner to tell you most of it.

Start the engine and wait until its fully warmed up. Add tps voltage to the scanner and start opening the throttle blade up with the set screw a small turn at a time as the IAC position will change slowly, hopefully dropping from 310 to below 100 counts. Adjust it so that it is 70-80 at hot idle. Keep an eye on tps voltage, as you want to keep it under .76v and this is just a rule. If it climbs over .76v before you get your IAC counts below 100, try loosening the set screw and rotating it back. You may have to drill a hole in throttle blade if this does not work, but that is the last resort.

After you have all this adjusted, turn the engine off, unplug the IAC harness and TPS, turn key forward to on (with the engine off) for 10 seconds, then shut off and reconnect everything. What this process does is it performs a TPS relearn so when you're idling without touching the gas, the PCM sees where the "new" 0% throttle position is instead of being at 1-3%.

Once this is done, let the engine cool down to as cold as possible and re-perform the idle-airflow.cfg config I attached above because now your base running airflow needs are different.

Hope that helps.




Is this what you were speaking on?

[edcmat-l1]

Yep you got it. I ain't got the patience to type all that out LOL

[InandOutPerfromance]

Ok, here is a log file. Take it easy on me lol

[blindsquirrel]

Well at least you know the knock sensors are working.

Is that real knock, like from combustion, or is something clanging around and triggering them?

[InandOutPerfromance]

Fine question. To my knowledge there is nothing clanging around. My biggest question is why does it want to pull all that fuel all the while its knocking?

[InandOutPerfromance]

Also that area of red is what i was talking about. That is where it bogs so bad.

[edcmat-l1]

Good chance most of the KR is burst knock. If it goes away with this file, that's what it is. If it isn't, the knock sensors can definitely be dumbed down some.

You're not logging any of the pids you need to setup idle airflow. Try the attached channel config.

You got a lot of other wonky shit going on too BTW.

[edcmat-l1]

Also that area of red is what i was talking about. That is where it bogs so bad.

The bogging is probably all the timing being pulled out of it.

[InandOutPerfromance]

So that went a lil better alot less in gear stopped bogging. Still a little studder of idle But i will say that was definitely a improvement. I grabbed the log for ya.

[edcmat-l1]

Knock retard is all still there.

This log it never went into closed loop.

You're not using the channel config I posted.

[InandOutPerfromance]

Forgive me but i dont know what to do with that link?

[InandOutPerfromance]

Oh and what was it you changed in the file if you dont mind me asking?

[blindsquirrel]

Oh and what was it you changed in the file if you dont mind me asking?

Open a file. Click 'Compare' and open a different file. Then 'View Comparison Log'...

screenshot.15-09-2023 13.10.45.png