2015 Procharged 5.7 Hemi 2500 stumble

[Kallibrated]

Hi Guys,

I had a 2015 Challenger on the dyno with a very peculiar issue. Let's start with the car. 2015 6MT 5.7 with a P1-SC, boost cam, ID1000s, stock exhaust with cats. The issue is that it misfires at 2,500 rpm at any heavy load. I don't have an exact number of airflow but it absolutely does it at WOT every single time. Floor it at 2,000 and right at 2,500 it stumbles, and then continues on its way. Car runs flawless otherwise. Plugs were changed with no affect. AFR, ignition timing, and cam timing have no affect on the issue. Attached the map and a log file that shows the misfire at time stamp 1:45. Any insight is appreciated!

Asghar ID1K Blower Cam_based on read image.hpt

street 1.hpl

[FlyinRyan]

I've seen this before. Edit: Sorry, didn't see you were using ID1000s.

From what I have seen this is related to injector data.

[Kallibrated]

I've seen this before. Edit: Sorry, didn't see you were using ID1000s.

From what I have seen this is related to injector data.

I assumed this was the issue from the previous tune which is why we switched to IDs. Used their data as well. Thanks for the input, though.

[superhemi]

have you fixed the stumble I have a vortech doing the same thing

[Kallibrated]

have you fixed the stumble I have a vortech doing the same thing

Not yet, will keep posted. Very odd and frustrating issue.

[Hemituna]

Not sure if it applies to you but here is one I had.
2015 JGC SRT ...ran perfect stock.
Fitted whipple and unlocked original ecu.
From first drive s/c it had a surge in the throttle as you slowly pressed the gas.
Logging showed throttle going from 25-30% to nearly 70% with only small increase in pedal.
Also would sometimes randomly stick open 30% after WOT run.
Other than that it ran/drove great rest of the time.
Spent weeks and weeks trying to sort it tuning/throttle tables, swapping T/B's, bypass valves, you name it - wiring - etc etc.
Was about to give up, so as last resort ordered another new unlocked 2015 PCM.
Threw same base tune in it and guess what......drives sweet.....tuned up easy as!
No idea what is wrong with ori PCM, maybe unlocking did something?? Don't care now
You never know this may be your problem too.....

[Mep_q8]

what do your VE tables look like at the area its happening? also wat kind of PR ratio are you commanding and how fast?

[superhemi]

Well since I posted asking if you had fixed it, we fixed mine, I ordered the two bar setup from procharger and installed and calibrated it, now the car runs great no more stumble, this whole time almost a year we have been fighting this. Good Luck

[JamieHRS]

Well since I posted asking if you had fixed it, we fixed mine, I ordered the two bar setup from procharger and installed and calibrated it, now the car runs great no more stumble, this whole time almost a year we have been fighting this. Good Luck

Was this not an option when you purchased the kit originally?

[mxatunerjg]

try running a little rich across this area. Say like 10.8-11.0 afr. I have been running into this on a lot of the newer supercharged hemi's. Seems like the only way to cure it is to richen the mixture through this area. On some, not all, they do show a very quick lean spike right at this rpm. At first I thought it was due to the stumble/misfire, but after richening the mixture the stumble would be gone. The lean spike would still be there but instead of spiking to 13 - 14 it would spike up to like 12. When I say spike I am talking about a spike that began at 2400 and was back to commanded by 2600 rpm. Very very quick. I will say I don't like this "fix" and I am going to keep working at figuring out what is causing it, but in the meantime this does seem to help it out. Next attempt that I plan to try is making some changes to cam timing in this area.

[JamieHRS]

mxa.... I think that was already tried on this car. But this car is also not running the procharger map sensor, and has a baro code since the mopar 3 bar was installed. This car does the same thing, at 2400 it starts to go lean, and by 2600 its brought back smooth and running fine. I also noticed it has a slight bit of knock when this happens. Did yours?

[mxatunerjg]

mxa.... I think that was already tried on this car. But this car is also not running the procharger map sensor, and has a baro code since the mopar 3 bar was installed. This car does the same thing, at 2400 it starts to go lean, and by 2600 its brought back smooth and running fine. I also noticed it has a slight bit of knock when this happens. Did yours?

Ok. That sounds like a map sensor calibration issue.

As for the knock, I have not seen a knock issue as much as the sensors picking up some noise from the misfire. Once the misfire is gone, so was the knock.

[06300CSRT8]

does anyone have a better log of the stumble? The first log from the OP is like a nano second of WOT, not even clear to me its stumbling. He lifted before it even got done with the transition to closed loop.

[superhemi]

Was this not an option when you purchased the kit originally?

Mine is a Vortech, so it came with a two bar they put in the kit that taps into the brake booster line, very ragged when they were trying to tune the car, after testing everything under sun, including trying a 3 bar, which it didn't like at all, I bought the procharger setup which installs where the MAP sensor normally is and dang it fixed the problem.

[06300CSRT8]

Mine is a Vortech, so it came with a two bar they put in the kit that taps into the brake booster line, very ragged when they were trying to tune the car, after testing everything under sun, including trying a 3 bar, which it didn't like at all, I bought the procharger setup which installs where the MAP sensor normally is and dang it fixed the problem.

You could have just relocated the vortech provided map sensor to the stock location.

[Kallibrated]

So we tried the Procharger 2 bar with stock SRT4 2 bar scaling which reads 98kpa a KOEO and pretty much traces the boost curve from before. Exact same stumble at 2,400-2,500 rpm. What odd is all readings look fine. The map reading is completely stable there, the only obvious change is the o2 reading during the misfire. On the dyno wideband I've ran it as low 11.8 here with no real affect. Furthermore, what's even stranger is every time it happened on the dyno, the spark signal would be lost for that 75 or so RPM suggesting that the power to the coils is being cut. We've also changed WOT pedal thresh hold volts back to stock with no change.

[mxatunerjg]

So we tried the Procharger 2 bar with stock SRT4 2 bar scaling which reads 98kpa a KOEO and pretty much traces the boost curve from before. Exact same stumble at 2,400-2,500 rpm. What odd is all readings look fine. The map reading is completely stable there, the only obvious change is the o2 reading during the misfire. On the dyno wideband I've ran it as low 11.8 here with no real affect. Furthermore, what's even stranger is every time it happened on the dyno, the spark signal would be lost for that 75 or so RPM suggesting that the power to the coils is being cut. We've also changed WOT pedal thresh hold volts back to stock with no change.

If it were me i would attempt to run it richer than that just to see how it reacts. Try 10.8 or 11.0. Where is your wideband sensor(s) mounted? Tailpipe pickup or up close to the engine? Are you running any CAT's? If so is the sensor before or after the CAT? Are you checking AFR on each bank pre x pipe?
As for the loss of signal, do you mean you lost ignition signal on the dyno or with the logger? Have seen issues in the past with dyno inductive pickups losing or giving very erratic signals during misfire events.

[Kallibrated]

If it were me i would attempt to run it richer than that just to see how it reacts. Try 10.8 or 11.0. Where is your wideband sensor(s) mounted? Tailpipe pickup or up close to the engine? Are you running any CAT's? If so is the sensor before or after the CAT? Are you checking AFR on each bank pre x pipe?
As for the loss of signal, do you mean you lost ignition signal on the dyno or with the logger? Have seen issues in the past with dyno inductive pickups losing or giving very erratic signals during misfire events.

I did find that running richer helps, no doubt about that, but there's no good explanation for it. The wideband was mounted in the rear o2 spot on the dyno. Through quite a bit of testing I've found that factory cats do not affect AFR as much as some think. I've done back to back testing finding only a very marginal difference. The lost signal I referred to was through the inductive pickup which grabs from the coil pack digital wires. I have found that misfire events typically do not cause the RPM signal to completely drop out (coils are usually still being fired) where as with this car the signal consistently completely cut out right at ~2400-2500.

[mxatunerjg]

I did find that running richer helps, no doubt about that, but there's no good explanation for it. The wideband was mounted in the rear o2 spot on the dyno. Through quite a bit of testing I've found that factory cats do not affect AFR as much as some think. I've done back to back testing finding only a very marginal difference. The lost signal I referred to was through the inductive pickup which grabs from the coil pack digital wires. I have found that misfire events typically do not cause the RPM signal to completely drop out (coils are usually still being fired) where as with this car the signal consistently completely cut out right at ~2400-2500.

While I do agree it does not make sense about running rich....so far this has been the only way I have found to keep this from happening. I have always tapered afr in with boost and rpm to a point, especially on turbocharged or centrifugal supercharger setups, but it just does not seem to work on these later model hemis. Like I said in an earlier post, I think I may make some cam timing adjustments the next time I run into this issue to see what happens.

As far as the O2 placement...I do agree there is very little if any difference between the pre/post cat readings. What I have seen though is the cats can mask quick lean/rich spikes probably due to the cats giving a location for the exhaust flow to slow and "tumble". I know with these vehicles it is near impossible to get an upstream location for a wideband on OEM manifolds and CATs, but it may give you some info to work with.

Have you tried your inductive pickup on other cylinders? Have you checked your afr on both banks?

I would say this, if you try running that thing richer and it stops the misfire I think you can be very confident it is not an electrical issue especially not with the ignition system.

One other thing I just thought about. I have only had this issue on centrifugal supercharged setups. If all the setups used a Hobbs switch to activate some form of fuel flow increase system could it be a small spot where fuel pressure is dropping just before fuel flow is increased by the activation of Hobbs switch? Maybe monitor fuel pressure if you are not currently doing so.

[FlyinRyan]

While I do agree it does not make sense about running rich....so far this has been the only way I have found to keep this from happening. I have always tapered afr in with boost and rpm to a point, especially on turbocharged or centrifugal supercharger setups, but it just does not seem to work on these later model hemis. Like I said in an earlier post, I think I may make some cam timing adjustments the next time I run into this issue to see what happens.

As far as the O2 placement...I do agree there is very little if any difference between the pre/post cat readings. What I have seen though is the cats can mask quick lean/rich spikes probably due to the cats giving a location for the exhaust flow to slow and "tumble". I know with these vehicles it is near impossible to get an upstream location for a wideband on OEM manifolds and CATs, but it may give you some info to work with.

Have you tried your inductive pickup on other cylinders? Have you checked your afr on both banks?

I would say this, if you try running that thing richer and it stops the misfire I think you can be very confident it is not an electrical issue especially not with the ignition system.

One other thing I just thought about. I have only had this issue on centrifugal supercharged setups. If all the setups used a Hobbs switch to activate some form of fuel flow increase system could it be a small spot where fuel pressure is dropping just before fuel flow is increased by the activation of Hobbs switch? Maybe monitor fuel pressure if you are not currently doing so.

I can tell you that I am having a very similiar issue on two Whipple'd Hemis. I have 25+ hours into a 15 Durango. I believe we may be making progress but it has been nothing short of infuriating.