Hemi Continues to quit at Speed.

Dubob said
Don't know if your running egr or not. My 04 Ram would shut down. No codes etc. I replaced the egr valve and it's been good for over 6 months.

I am running an EGR valve.

joeboy said
Tin,
If I was looking at sensors, Id look at crank and cam sensors, but in my head I see a heat related failure taking longer to "reset", (heat would raise before it fell right?) so Im thinking voltage or ECU. It may be worth keeping a volt meter in the car and checking 12v + at your ign and ecu relays before you touch the key when it dies. Id also talk to hotwire about a reflash before you popped for a new ECU. You may even be able to see if one of these factory ECU guys would loan you theirs as a "known good" before you drop the cash...

Another thought may be what Tstat are you running? The factory 203* stat was hell on my underhood temps. I switched to a 185 and t has really helped my XFI system. You gotta reprogram the fans, but dropping 20* under the hood may solve the problem if it's heat related...

JOE

Thanks Joe, I am running a 180 t-stat, as for voltage, I have not checked with a meter, but my gauge is rock steady at 14+V.

Tech857 said
Tincup I was working at a Dodge dealer for the last 22 years. There's an issue with some of the Hemi engines where an interaction between sparkplugs and coils takes the pcm offline for a second and shuts it down. There was never a complete explanation from Chrysler on this but the diagnosis starts with making sure that you have a set of Oem plugs. I quess there's some counterfeit ones out there. Then try swapping out 1 coil at a time with a new to see if it is one of the coils the takes it out. If you find that the issue is not one of the coils then you replace the pcm. This seemed to usually happen on 06 to 08 engines. We would replace all the coils and plugs and then finally the pcm if needed.

I just installed a new set of Champion plugs ( OEM ), and I have thought about the coils because one other problem I have been having is my tach will bounce ( drop to zero ) occasionally. I thought the two were connected, but now I'm not so sure.

joeboy said
Tin if you wanna give this a shot I have a complete set of 05 coil packs I swapped off my motor before I ever fired it, they are all brand new and I'd happily ship them to ya to try a road test with at least... If you wanted them to keep, I'd make ya a pretty good deal...

Joe

blown71duster said
Just to clarify on the coils shorting out.

The hemi engine valve covers have rubber isolated bolts and if the coil secondary of any coil shorts out against the valve cover it goes to the path of least resistance which can be a nearby harness and spikes into the pcm and will cause a symptom like you explained.
It shuts down the pcm and stalls the engine and then is fine on a restart.
I have heard of guys just start replacing components , sensors ,pcm, etc , and still have same problem because the ground straps are broke, or in the case of an engine swap missing.

I looked at a 04 ram in the shop and it had a ground strap on the valve cover bolt that loops from the top of the bolt back around the rubber to the base of the bolt so if it the coils short out it will shoot the secondary voltage back into the head/block ground.

Might be worth a shot to run a ground for a test. One on each valve cover.

I do have the alum valve covers, I will check to see if the ground wires are there. I did ground both heads when I wired the car.