Cylinder de-activation is driving me insane.

[fumanchu182]

So if someone has .02 cents they'd like to share I'm all ears. Today once again after a pull, cylinder 8 said bye bye. Pulled over, shut the car off, turned it back on and it came right back. There are no mechanical issues with the cylinder at all. The PCM is doing something it shouldn't be doing and I don't know how to stop it.

Here is a screenshot of the logs.

They are also attached as a log. In the tune I have turned of everything I can think of.

[ECM] 45667 - Misfire RPM Min: Below this value Misfire will be disabled. - As you can see I never see 8160 rpm so this should be moved out of the way.

[ECM] 4049 - Catalyst Damage Noise Threshold: Noise threshold per cylinder to trigger fault.
[ECM] 4049 - Catalyst Damage Noise Threshold: Noise threshold per cylinder to trigger fault.
^^^^^ I have no ideas what these tables are and left them alone... Does anyone have any tips or trick for this?


[ECM] 39209 - Weighted Catalyst Misfire: Weighted Catalyst Misfire vs RPM vs MAP. - I maxed out these values, HP Tuners will not let me go any higher. This could be a cause, I managed more than 255 misfires while fucking around and well here I am.


This table is a clusterfuck. Even with parameter access I still can't edit it, maybe a bug in HP Tuners? This could be interfering but my hands are tied. Also updated today to 5.1.1220 beta and it is not editable still. I'll reach out to HP Tuners on this one, also reached out on the @ostmike thread to see if he can edit this able. @Jon-MooredPerformanceLLC can you edit this table?


I have no idea wtf this is for. I know the hellcat firing order is:

These are intimately linked but I haven't figured it out, can someone explain this?


Raised temps to 300F, definitely not seeing this temperature. For some reason the labels in the table are not correct, wonder if this is an issue.

If anyone can help it would be appreciated. Kinda at my wits end...

 

[1971demon]

Way above my pay grade....somebody must be able to figure it out for you GL

 

[Bobo]

Didn't know these cars had cylinder deactivation???

 

[MiHiHemi]

Time to deactivate deactivation?

 

[EricG]

I think he's being sarcastic? Only 5.7 and 6.4s with the A8 have intentional cylinder deactivation.

 

[Bobo]

I think he's being sarcastic? Only 5.7 and 6.4s with the A8 have intentional cylinder deactivation.

I hope that's the case.

 

[Slowpoke387]

I hope that's the case.

It is.

 

[Magnified]

I personally have never even heard of that before, but I'm not longer into the nuts and bolts of tuning (not for more than 10 years). Don't understand why it would be just 8. And it reactivates immediately with just a key-out and restart cycle?

 

[ostmike]

I bet you had a "compare" tune opened and then closed it while viewing this table marked "Read Only".
Exit VCMeditor and then open only the tune you want to edit. Do not open a compare file. I have had this same issue happen on other tables that are normally editable and the above was what I had to do.

 

[Hunter]

I think he's being sarcastic? Only 5.7 and 6.4s with the A8 have intentional cylinder deactivation.

My 5.7 had the MDS. My 6.4 did not.
Is the MDS what you are referring to?

 

[Unholy707]

Is it completely deactivating? Cyl 8 is always an issue in these cars. Pull the plug and check for bad blow by. There’s an oil fill port right in front of Cyl 8. I used to get misfires like crazy and #8 was always off the charts. It was due to a warped whipped 4.5 plenum. Also, I have heard the heads on the older hellcats we’re just thrown on and not well aligned, so supercharger doesn’t sit square. Once I got the FI o ringed spacers it solved all my issues.

 

[Unholy707]

If you pressurize the crankcase it’s going to come out there and bleed right over to the cylinder. Have personally have it happen. Same if it’s not sealing by the oil fill provision in the head by cyl1, which will pressurize crank case and force oil out of the oil fill provision in the head by cyl 8.

 

[Unholy707]

Horrible design, considered having mine welded up

 

[Unholy707]

Also, I believe you can log MDS in your channels to see if it’s activating. If HPT doesn’t have it, I’m pretty sure Alfa does, and you can record as well - it’s not the best at logging, but it will give you info. Even though you don’t have the solenoids. Could be lifter related? My money is on oil shutting down cylinder 8. Just because you have the misfire thresholds maxed doesn’t mean it’s not misfiring

 

[EricG]

My 5.7 had the MDS. My 6.4 did not.
Is the MDS what you are referring to?

Yes MDS, was your 6.4 a manual? All A8 6.4s have MDS I believe.

 

[Unholy707]

Idk, my service manual for my 6.2 hellcst says 6.2 supercharged MDS 😅

 

[Hunter]

Yes MDS, was your 6.4 a manual? All A8 6.4s have MDS I believe.

No mine was an A8.
No MDS on the 485 hp 392 hemi.
MDS on the 5.7 though

 

[Unholy707]

Idk, I removed eco mode from my car so don’t have to worry about it (besides it not actually having kids) lol

 

[Slowpoke387]

No mine was an A8.
No MDS on the 485 hp 392 hemi.
MDS on the 5.7 though

My 2015 392 SRT had it. A8. Hated it. Under light acceleration/cruising it would drop a couple of cyls. Heavier accel would wake it up. I think it depended on mode too.

 

[Magnified]

Why did you hate it, specifically?

I dont even own one, but the killing the motor for stoplights gets my attention when i have the window down. Disconcerting for me to hear several engines fire up as the light turns green.