PicoScope 7 Automotive
Available for Windows, Mac, and Linux, the next evolution of our diagnostic scope software is now available.
14 RAM hemi misfire
14 RAM hemi misfire
Hello everyone. I have a misfire situation here that I wondered if I could get a little help with what direction to go in. First of all. this was bought at the auction. Its a 2014 RAM 2500 P/U with a 6.4L HEMI with 175K miles
Trouble code is simply a p0300 multiple miss. the cylinders missing are 1-4-6-7
A couple of the tests I do not have waveforms for, sorry I did not save them. The spark plugs for the missing cylinders were completely gas soaked. the others were covered in black soot. these engines have 2 plugs per cylinder with a double ignition coil. I replaced all the plugs. and switched 1 &3 coils around. the same condition occurred with no change. I scoped the secondary with the scales of the automotive menu and they all looked ok but when i took a larger time base the missfire cylinders showed very little positive KV as opposed to the good cylinder. I checked the current rams for both a good and missing cylinder and found the missing one is getting 1/2 the saturation. So my next step was to check the control from the pcm on uthe missing vs good cylinder which i have that waveform as well. the last thing I did was jumper a known good 12v to a missing coil which did nothing for the problem. see what you think I should do next. thanks
Trouble code is simply a p0300 multiple miss. the cylinders missing are 1-4-6-7
A couple of the tests I do not have waveforms for, sorry I did not save them. The spark plugs for the missing cylinders were completely gas soaked. the others were covered in black soot. these engines have 2 plugs per cylinder with a double ignition coil. I replaced all the plugs. and switched 1 &3 coils around. the same condition occurred with no change. I scoped the secondary with the scales of the automotive menu and they all looked ok but when i took a larger time base the missfire cylinders showed very little positive KV as opposed to the good cylinder. I checked the current rams for both a good and missing cylinder and found the missing one is getting 1/2 the saturation. So my next step was to check the control from the pcm on uthe missing vs good cylinder which i have that waveform as well. the last thing I did was jumper a known good 12v to a missing coil which did nothing for the problem. see what you think I should do next. thanks
- Attachments
-
- 7 & 8 COIL CONTROL.psdata
- (1.16 MiB) Downloaded 322 times
-
- RAM ODD COIL SECONDARY.psdata
- (893.81 KiB) Downloaded 314 times
-
- 14 RAM COP CURRENT.psdata
- (707.7 KiB) Downloaded 308 times
Re: 14 RAM hemi misfire
Interesting problem!
Does this truck have the MDS system? If so I would start by checking this is functioning correctly as MDS shuts down cylinders 1, 4, 6, and 7 when active. I am not massively familiar with the system but I think if the solenoids are stuck open you will have no valve operation.
Can you scope solenoid current and voltage? Or even better, running cylinder pressure in a good cylinder and a bad cylinder with a WPS?
Mark
Does this truck have the MDS system? If so I would start by checking this is functioning correctly as MDS shuts down cylinders 1, 4, 6, and 7 when active. I am not massively familiar with the system but I think if the solenoids are stuck open you will have no valve operation.
Can you scope solenoid current and voltage? Or even better, running cylinder pressure in a good cylinder and a bad cylinder with a WPS?
Mark
Re: 14 RAM hemi misfire
Hi Rburgy,
I'm sorry to tell you but you don't use your scope properly.Scope sample interval in secondary waveform is 25 microseconds,it's to way slow to be useful in my opinion.It's a same story with coil control waveform (50 microseconds).Maybe that's way you have odd kV spikes.You need to set scope for 1 microsecond between samples for optimal secondary waveform in my opinion (someone would like faster but I don't).So when you enlarge time base you should enlarge scope samples per screen also...This way it's hard to analyse waveforms and help you...
Voltage/vertical scaling is also wrong but that isn't big problem...
Best regards,Dejan
I'm sorry to tell you but you don't use your scope properly.Scope sample interval in secondary waveform is 25 microseconds,it's to way slow to be useful in my opinion.It's a same story with coil control waveform (50 microseconds).Maybe that's way you have odd kV spikes.You need to set scope for 1 microsecond between samples for optimal secondary waveform in my opinion (someone would like faster but I don't).So when you enlarge time base you should enlarge scope samples per screen also...This way it's hard to analyse waveforms and help you...
Voltage/vertical scaling is also wrong but that isn't big problem...
Best regards,Dejan