Hemi has baby chop.

[jratdebom]

Hello everyone. First post here! I have been tuning a texas speed stage 2 cam in my 2019 5.7 hemi charger. 218/226 at 0.05in and 112 degree LSA. The problem I've been having is that it will chop, but it is a very fast paced chop (sounds like a ghost cam). It seems to do this no matter the idle RPM I choose. Ive done a lot of research around the internet on how to make one of these cars chop and nothing has helped. It sometimes will chop nice and slow right after it starts and then just settles down to fast baby chops. Does anybody have any advice? Am I missing something? I have adjusted the minimum timing tables and Proportional P/N table too. I also double checked, and yes my minimum spark is allowing -64 degrees if i so desire.Choppa.hpt

[james1595]

That cam isnt going to have alot of chop, probably less than you think. Also i think when it changes its correcting itself. Not sure if there is a way to stop it though

[dodgeboy]

See if someone makes an old school grind with lots of overlap, you'll have to eliminate VVT and run a vacuum pump for your power brakes.

[jratdebom]

I have deleted VVT. The car chopped nicely before tuning it, of course until the PCM figured out what was going on so it just died on every startup.

[MakurFab]

if you have done some reading like you said then i am assuming you understand you ran across how PID controllers work . my tune to compare to is attached and a short clip to here it idle.
https://youtube.com/shorts/K3N-U0xUfpY

[jratdebom]

its got a great chop for a 6.4 mds cam. great job. I didnt really adjust the integral and derivitive tables so im gonna try that next and will get back to you this thread. thank you for the help.

[MakurFab]

its got a great chop for a 6.4 mds cam. great job. I didnt really adjust the integral and derivitive tables so im gonna try that next and will get back to you this thread. thank you for the help.

Not a problem at all, you have a couple other tables that could use some attention that will affect the idle for instance base spark min. table. and a small tip regarding idle speed (not rpm) but the rate that creates the fast and slow chop you mentioned. The smaller the numbers in the table headers are the faster it will chop.

[james1595]

So the bigger the number in the integral table the slower it chops to? Also is there any other table that needs adjusted to get a good chop? I know about the base minimum table, just wondering if there are others

[MakurFab]

So the bigger the number in the integral table the slower it chops to? Also is there any other table that needs adjusted to get a good chop? I know about the base minimum table, just wondering if there are others

your proportional P/N table needs to have a zero set point and is the main table that defines the idle prop pn table needs a zero set point.png

. the I and D define how quickly the rpms recover from error and the history of the idle from my understanding. that zero acts as the idle rpm that is set under the idle rpm tab for that situation. the way that help me is thinking of it like a tennis match. the ball is your current rpm, the net or zero is the commanded rpm. the players are the torque factors in the idle airflow tables. the analogy given isn't quite accurate but you get the idea.

The column and row table headers defines how quickly the ball travels and how far it must go. if one player is say 500 rpms away from zero it has to apply enough torque to hit the ball to the opponent's side of the court. how much power defines where the ball lands. now say the the opponent is closer to the net like 200 rpms not as much torque is needed but if an equal amount is applied the ball travels faster and the other play might miss and the ball overshoots the commanded rpm.

made a couple changes to give you a starting point. Choppa. rpm_airlow_torque loss_base idle changes hpt.hpt

[Spray-Cam Hell-Ram]

There are quite a few tables that will have an effect on cam chop. Makurfab explains the logic pretty well using the Tennis analogy. Personally, I have the proportional P/N table set at -50 in all negative inputs and +50 input in all positive inputs and the 0 input. And if you have an otherwise pretty stable idle to start with, then you can also get away with doing the same on your proportional drive table as well to get a good chop at a light. (I have -35 and +35 in the drive table but 0's in the 0 column). And as already mentioned, Integral and Derivative tables control idle speed. And have to make sure to have -64 there in there in the last column or two in the startup table. But what a lot of people seem to miss is making sure they have timing in the minimum base table set low enough in the idle area to support a good swing in timing. For example, if you have timing at start-up set at say 10-12 degrees but your inputs in the idle area of the minimum base table is, let's say 5, then you are only going to have a swing in timing from 5 to 10 degrees for your idle whereas a spread of 20-40 degrees in timing, from my experiences anyway, will enhance the idle chop effect, whether that be a swing range (While in Park) of -20 to +20 degrees or even -30 to 0 degrees. Either of these ranges seem to produce a descent chop effect, but you may find that you prefer one over the other depending on how you have your Idle Prop, Int, and Der tables set. You've just got to play around with inputs in these tables to find what you like personally and what will maximize your cam profiles potential to chop. Find a set of inputs that gets you closer to what you are looking for, and then from there just make adjustments to just one of the tables and see how that changes your idle and then go from there. It helps when approaching this to do some due diligence and do some research to read up on what these PID controllers are and how they work so you at least have the base understanding that your Prop tables are what create your baseline, then your Integral tables work to start dialing in what your Prop tables have set-up and started, and then your Derivative tables step in to close the deal and fine tune it to a steady idle. I usually like to have my Prop and Integral tables set higher which puts a bit of pressure on my Derivative tables ultimately to stabilize this choppy idle I've created by inputting higher values in the first two sets of tables, so I will set my Derivative tables values on the lower end and then work those values down to 0 as I work my way towards the center to stabilize the choppy idle. Hopefully this makes sense and helps some of you guys out there working to get your best possible chop.

[MakurFab]

There are quite a few tables that will have an effect on cam chop. Makurfab explains the logic pretty well using the Tennis analogy. Personally, I have the proportional P/N table set at -40 in all negative inputs and +40 input in all positive inputs. And if you have an otherwise pretty stable idle to start with, then you can also get away with doing the same on your proportional drive table as well to get a good chop at a light. (I have -35 and +35 in the drive table). And as already mentioned, Integral and Derivative tables control idle speed. And have to make sure to have -64 there in there in the last column or two in the startup table. But what a lot of people seem to miss is making sure they have timing in the minimum base table set low enough in the idle area to support a good swing in timing. For example, if you have timing at start-up set at say 10-12 degrees but your inputs in the idle area of the minimum base table is, lets say 5, then you are only going to have a swing in timing from 5 to 10 degrees for your idle whereas a spread of 20-30 degrees in timing, from my experiences anyway, will enhance the idle chop effect.

Well look who chimed in!!
I made a small mention on the base spark table but I wasn't going to give him all the answers. That's how they do things here if I'm not mistaken!!! I was waiting to see if he found your video or the other video by Reckless explaining the steps....

[jratdebom]

There are quite a few tables that will have an effect on cam chop. Makurfab explains the logic pretty well using the Tennis analogy. Personally, I have the proportional P/N table set at -40 in all negative inputs and +40 input in all positive inputs. And if you have an otherwise pretty stable idle to start with, then you can also get away with doing the same on your proportional drive table as well to get a good chop at a light. (I have -35 and +35 in the drive table). And as already mentioned, Integral and Derivative tables control idle speed. And have to make sure to have -64 there in there in the last column or two in the startup table. But what a lot of people seem to miss is making sure they have timing in the minimum base table set low enough in the idle area to support a good swing in timing. For example, if you have timing at start-up set at say 10-12 degrees but your inputs in the idle area of the minimum base table is, lets say 5, then you are only going to have a swing in timing from 5 to 10 degrees for your idle whereas a spread of 20-30 degrees in timing, from my experiences anyway, will enhance the idle chop effect.

Ill have to look at the proportional table. I do have it allowed to go -64 degrees on the startup table and the base table is from -40 up to 5 degrees depending on the vertical values in the graph. (bottom is negative 40 and top is postivie 5 to keep the engine on (reckless motorsports video). Tried making it -40 all the way up the base chart and it ran but it was very smooth.


I have a lot to do when i get home thursday hahaha. Cannot wait for this.

[jratdebom]

This guy has a video on making a hemi chop? Only one ive seen is reckless motorsports. Could you link it?

[Spray-Cam Hell-Ram]

You actually did a fantastic job explaining the tuning changes needed for a good idle chop and the logic behind it. I'm sure some may say you gave away too much, but I am not one of them...Well said for sure! I'm liking the content in this thread..

[Spray-Cam Hell-Ram]

I've talked about it a bit in a few threads and have a video clip or two posted out there somewhere (I personally haven't kept track of any of these myself) from others of my truck's cam chop and talked about it in one of those clips. I'll see if I can't make a clip and post it up on here for those interested.

[dodgeboy]

I have a 5.7L with a Comp Cams 274 Cam and a Whipple 2.9L Stage 2. I know the idle I want but I am worried it will throw codes and stall when coming to an idle.

https://www.youtube.com/watch?v=CdPr9919xwk&t=17s

[MakurFab]

This guy has a video on making a hemi chop? Only one ive seen is reckless motorsports. Could you link it?

I have several videos of various idle configurations and exhausts setups. give me some time to find them and upload.

[MakurFab]

I have a 5.7L with a Comp Cams 274 Cam and a Whipple 2.9L Stage 2. I know the idle I want but I am worried it will throw codes and stall when coming to an idle.

https://www.youtube.com/watch?v=CdPr9919xwk&t=17s

the only codes that have come up for me are misfire codes due to the large swing in some of the idle tunes when i was trying to figure this tuning stuff out a couple years ago. change the tune by modifying the misfire threshold and disabling the dtc set or modify the idle swing.

[MakurFab]

I've talked about it a bit in a few threads and have a video clip or two posted out there somewhere (I personally haven't kept track of any of these myself) from others of my truck's cam chop and talked about it in one of those clips. I'll see if I can't make a clip and post it up on here for those interested.

what I am really scratching my head over is all anybody ever talks about is the P/N idle. I want in drive as well and nobody seems to talk about that so its trial and error I guess.

[dodgeboy]

the only codes that have come up for me are misfire codes due to the large swing in some of the idle tunes when i was trying to figure this tuning stuff out a couple years ago. change the tune by modifying the misfire threshold and disabling the dtc set or modify the idle swing.

Did you hear the car in that video? LOL I had a highly recommended tuner tune my car, I don't need to put my stupid fingers in it. I just get a P0308 after the car sits all winter and I take it out in the spring and thrash it.