Cams Causing Misfires

I am still in the process of trying to tune my LT1 Camaro with a 228/236, 114 LSA, 111 ICL, .635/.635 cam, ported heads, ported intake manifold, ported throttle body, and rotofab. I have done at least 30 iterations of VVE and MAF tuning and it seems like I can't get them dialed in any better due to not being able to find ways to filter transients and inaccurate wideband data along with trouble curve fitting and calculating the coefficients without large calculation errors. Long term trims for the most part are under 5%.

I am having quite a bit of issues and I think this issue should probably take priority since I believe misfires are bad? I know they are at least bad for the cats, I care about the cats but most people don't. I still am trying to find someone I trust who will weld in an extra bung to my stock exhaust for the wideband, so I have only been able to gather wideband data by removing one of the front O2 banks and replacing it with the wideband. Wideband is showing WOT error within a couple percent as well so I know my fueling is good enough to not be a problem.

I have tried endlessly reading trying to decipher all the torque PID's and try to relate them to anything in the tune files, but it appears that maybe with traction control on, the misfire issue is worse maybe because of the lower timing? I can also feel at part throttle sometimes what feels like very subtle hiccup things that I never noticed stock that I am assuming are misfires. The misfire PID's don't make any real since to me and no one seems to understand how they are counted and reset, but the scanner is detecting a few now and then. I have heard that misfires are somewhat normal, especially with bigger cams?

Now the WOT misfires are noticeable, and I actually thought it was torque reduction from some unknown GEN V torque-based quirk pulling timing until it threw a code for random misfires after going WOT in second gear. Since I know it can't be my AFR since I've gotten those dialed in good, I am thinking it maybe something to do with injection timing? I have added 15 degrees across the entire SOI table based on the increased duration of my cam specs. I still have my stock exhaust with both cats complete and after the cam swap it smells like I have completely removed the cats. I am wondering if maybe its because of the misfires letting unburn fuel by? or is it normal with a cam for the cats to no longer work with the increased overlap?

I have also been fighting a P015A and C code for delayed response from lean to rich on both O2 banks. I have tried messing with the integrator delay and proportional fuel constant increasing and decreasing and vise versa and have seen no effects. Its like only one bank at a time will just sit there at full lean or rich until finally it moves. It looks like there is just no info out there for the GEN V with cams, since most everyone goes FI, but you would think there would be some common protocol for what you have to do to fix all of these quirks after adding a cam in a GEN V, and I know most GEN IV stuff applies as well.

Attachment 96875

Attachment 96876

Thanks everyone for the help

check your plugs it could have a crack from over tightening

I'm dealing with WOT misfires as well, have for months. Last year when i installed my supercharger, I guess somehow i nailed everything on the first shot. Being just an amateur, I figured there is NO WAY i could have done that so in my mind I still had more work to do. If anybody here is from Houston and used to go to AMC 30, mine was the blue C7 with the big ass APR wing on the back. It ran great. I was beating turbo'd M4's and could hang with a 1000hp turbo'd truck.

But again i figured there is no way I got it that good on the first shot, so i started fucking with it. Then a few things happened. My PC crashed in the middle of working on it and my original tuner "lost" my base tune then passed away(not mowtown). So now im stuck and probably have to admit defeat and find a reputable tuner in the area to clean it up. There are a few stock tunes in the repository but i have been reluctant to use those as a baseline. I was able to get the VE tables to act correctly by reworking my zone boundaries and my MAF tune is spot on.Startup, idle and cruise is fine. I know it's in the tune but just cant figure it out.
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So I actually did have an arc that was grounding out on some scratches on the spark plug boot metal heat shield. I sanded the rough spot down, where I had used a screwdriver to pry against it to get it off, on the heat shield and it stopped. I have since checked several times with the car running in the garage in the dark for more arcing but I haven't found any.

I feel the same way as I've never had a chance to tinker and tune anything really modified that much until now and I feel like all I did is tune VVE a little and now trims and fuel look pretty good and it runs almost like stock, except for idle.

Now I guess it could be checking for arcing at idle and it be fine but at WOT, when dwell and voltage are increased, it could be grounding out. I need to figure out how all the misfire PID's work, it looks like I will have to maybe log each cylinder PID.

So just now today, it finally threw a catalyst inefficiency code for both banks. So either I have destroyed my cats from misfires or from improper fueling, or either its expected to throw a catalyst inefficiency code when you have a cam? since maybe the increased overlap causes problems?

I am going to log all the misfire PID's I can and see what they are saying. I just don't know whats normal to expect with a cam and what is not. It's not like I have a huge cam and the specs are more in line with say the GM hot cam and even less on the duration.

So I may have some good news. I just took a long log recording all the misfire PIDs. The bad news is there are a lot of misfires (not sure how much "a lot" is since I don't have a stock log with misfire data to compare to). The most history count is cylinder #7 at 254 counts of history on a 27 min long log. All of the other cylinders have similar numbers except for number 8 which only has 25. So far that doesn't make me think I have plug issues, I torqued the spark plugs with a torque wrench all to the torque spec when the cylinder heads were off the car so I don't think I would have overtightened one.

The good news seems to be and hopefully it will stay is that the P015A and C for the delayed response from lean to rich codes have gone away, they were permanent as well too. From looking at the log it kind of seems they look like they may be switching better instead of hanging up but I still can see some hang ups where they remain in the rich or lean state:
Attachment 96879

Initially I had followed what I saw GHuggins and Higgs posts from people with similar problems but they had long tube headers. They suggested lowering the proportional base airflow, and increasing the delay. Well I thought about it and it made more sense to me that if the O2 response is sluggish (maybe due to having a cam with significant overlap causing a lot of EGR effect especially at lower rpms and idle) that the amount of fuel to cause the switch to rich would just have to be increased, as well as the delay before increasing the fuel to switch (integral delay) has to be reduced. So far I am not very optimistic that this will stick, maybe the code just wasn't wanting to report on the HP tuners logger (which always happens) or I am just on the edge to triggering the code. Long term trims seems to still be pretty good mostly around 5 and some occasional 7 or 8's:
Attachment 96880
But there are still occasional spikes in cells up to 25% for short term trims:
Attachment 96881

Considering that the misfires may be real, I guess its possible with my cam especially at idle and low RPMs where there is a lot of charge dilution. Now for the misfiring I see at WOT it is my suspicion that since I can't dial in my torque tables like stock, when the traction control or whatever goes to reduce torque its pulling a lot of timing, maybe more than is needed. So I am maybe getting the misfires at WOT when it downshifts to second gear although this is harder to believe since at this high of RPMs charge dilution should not be an issue since this is in a higher VE% area of the cam, on top of that fuel mixture is rich during PE.

As for the misfires at idle (I don't notice much misfire counts driving down the highway at cruise) I think I may have to richen it up? I guess this would maybe make the unburnt fuel smell worse at idle, which I hate that smell. Maybe it would cause the misfires to go away, and maybe the misfires are the whole reason I am getting such a unburnt fuel smell and catalyst inefficiency codes?

Filter those tables and you'll probably find that the high stft's occur on dfco entry. Also, two of the areas on you screen shot where you circled low mV areas (the two that drop all the way down) are indicative of dfco being active.

Thanks Rob, so I disabled DFCO when I tuned the VVE and MAF, but on this log it was re-enabled. So I agree it could have been a transient where DFCO was ramping on.

I tried using some filtering techniques on the MAF and VVE tuning to try to filter out the transient WB readings but I could never get anywhere.
I made up my own filter that I was hoping would filter out only cells where timing was at least 5 degrees and the RPM derivative did not exceed 50 rpms:

[50110.161]>5 AND ([50070.56.avg(2500)]-[50070.56.avg(-2500)])<50

It didn't give me an error but it appeared not to filter anything, not sure what I did wrong but it works to filter out 5 degrees and above alone, but the derivative is not working. It should take RPM and look 2500ms both forward and backward and take the difference on the averages, this in theory should give me a derivative of RPM which I would like to only show data where the derivative is under 50 rpms. This should allow sufficient time for transport delay and other factors to reach steady state and give a more accurate AFR.

I got to the point where it seemed I was just going in circles trying to refine MAF and VVE anymore so I put the stock narrowband back in and went back to closed loop. The good news is the delayed response lean to rich DTC hasn't come back, so it appears the adjustments I made to the proportional and integral delay maybe has worked.

Also some more kind of good news is after experimenting with the idle I just went ahead and zeroed out the torque reserve and it has greatly stabilized my timing at idle, but the bad news is it may have helped the idle quality a little but I am still getting the bucking back and forth. What I don't get is now the timing looks good and somewhat smooth in the scanner now, but I still have the bucking. I am assuming the bucking feeling is just due to the cam overlap and the associated misfiring? Its bad especially at a rolling idle when you have your foot slightly on the brake, you can feel it pulsing and bucking forward and backward.

Have you tried lowering the Virtual Torque tables in the area's it's bucking. You commented on my thread about how you didn't think it need to be changed. But my cam was doing exactly what your talking about when at a stop light with your foot on the break. After I lowered them it feels much better.

So yes I tried that, but maybe I didn't do it enough, or maybe too much? I think that's the issue I just wish I could understand all the torque PID's and how they relate with the calibration parameters we have available to change. Since none of the torque PID's correlate with the virtual torque calculation, I just don't see how we can adjust the VT. I feel I just can't win guessing and checking. I know most people don't care but I would like to make the torque system work like stock. I want to be able to use the launch control (which I believe is controlled by the BCM or something weird) and have the traction control work like stock.

I am assuming with big cams you just have so much reversion that even if the stock torque tables reference a lower torque value now that your cam doesn't have as much VE at lower rpms, this doesn't reflect reality?

I lowered mine -15 in the lower area?s then another -5 and I probably could have gone another -5. But I?m getting headers and adding my wideband I have in the closet into its y pipe. So I?ll be making more adjustments to the tune then. So for now it drives just fine.

Goat Rope has a really good video on how to adjust them to get the predicted torque and actual torque to line up better.

I did watch the video. From what I see on my logs my immediate and predicted torque commands are mostly within about 8-10 ftlbs compared to delivered engine torque, so I'm not real convinced I need to adjust virtual torque? I did try it and it doesn't seem to change anything. I still believe in theory if the cam makes so much less torque at low rpms and idle due to the valves being open too long and bleeding off pressure, the the GM calibrated factory virtual torque table should read the lower airmass and report the lower torque, I'm curious what I am missing here? is it the overlap and EGR effect causing the airmass to be overreported?

Zeroing out the reserve torque tables is the only thing that seems to have changed anything to do with idle besides adjusting speeds. Now its kind of debatable weather it was a good change or not, the spark advance is definitely a lot smoother which tells me the ECM was trying to keep a reserve of torque that wasn't possible and causing the control to go unstable. I am going to slowly start adding more torque reserve back in until I start noticing the pulseing/bucking more. I also wish I knew how much bucking is normal for a cam this size so I know if what I am trying to accomplish is not achievable.

So a great example of GEN V torque confusion happened today and I got a log of it.

I tried to got WOT and it felt like I only had about 100hp, I could tell from the sound it was pulling timing. I created a torque delivered vs commanded error math parameter, one for predicted and one for immediate:
Attachment 96943
You can see there is very low error between immediate commanded torque and delivered engine torque, its clear immediate commanded torque is limiting full timing and full power here. You can see from TPS there is no throttle limiting, MAP is good, and MAF is high, the airflow is there, pulsewidth is there, and pump pressure is there but there is no power.
The timing numbers just don't add up, and yesterday everything was running fine, this is completely random and just decided to start happening today:
Attachment 96944
You can see predicted torque is behaving fine, the driver is commanding torque from the axel, and the engine is being commanded by the axel to make torque, but the immediate source is still none, and its apparently way less than it should be. And why is there no immediate axel torque source?:
Attachment 96945
This just makes no sense and I feel like someone could have named these PID's way better and eliminated a lot of the redundancy. And again this is completely random it was just working fine. My next thing I guess I need to try is to disable the misfire testing to make sure its not going into some weird limiting mode when it detects misfires, which I guess is normal for a big cam.