Never posted before, I think I have a wiring issue and looking for clues to find the culprit, my jeep is an 05 crd, had it about 4 years now and lately its been giving me issues. It starts and drives fine most days but sometimes it will lose all power and start running poorly. Upon further investigation when it happens cyl 1 and 4 are no longer firing, I have to shut it off and do the Jeremy Clarkston method of fixing it by wacking the engine cover a few times as if its a drum, surprisingly works quite well, however I'm finding that I need to do it far more often nowadays. I'm at a loss here, the harness looks unmolested and completely serviceable. any tips would be greatly apprecieated, this is my only car and shes got over 240thou miles.

Start by pulling codes.
Trouble codes can help identify specifically which cylinders are misfiring.

How do you know its cylinders 1 and 4?
How do you know its only cylinders 1 and 4?

Its possible that you might have some loose connectors on the injectors.

_________________
U.S. Army Retired

I know it's 1 and 4 by disconnecting them while it's running, as it makes no change in the way it runs, the codes I get are po300 po201 po202 po203 po204 and the codes don't pop up until after I shut it down and restart it

Also in the process I check that the connections are seated correctly

Just to belabor the obvious - if whacking the engine cover fixes the problem for a while then it's a 99.99999% certainty that you have a wiring/electrical problem between the plastic engine cover and the top of the engine. There are several known places on that wiring that wear and cause intermittent shorts. Were it mine I'd take the plastic cover of; open up the harness and inspect every bit of wiring although before doing that you might idle the engine in Park (keep hands away from fan and serp belt) and wiggle wires and connections to see if cylinders drop out. Off hand I'd suspect wires to injectors that "tell" them when to inject fuel but could be wonky cam sensor connection.

_________________
Sold to LOST member my 05 Ltd, GDE Stg II turbo + TCM tune, SunCoast TC w. Transgo kit, Steiger window regulators, Samcos, Fumoto valve, 2nd gen filter head with Lub. Spec. bleeder, Hayden clutch & 11 blade fan, inverted spare, P-1 battery, BF Goodrich Long Trail TAs, Etecno1 glow plugs, timing belt at 50K miles/8 yrs

All those codes indicate misfires at every cylinder. Not just 1 and 4.

Clear the codes and run it again.
But instead of disconnecting the injector, just wiggle each connector to see if that causes a misfire.

And like Papa says, do a thorough check of all the wiring.

_________________
U.S. Army Retired

ok had a good day of tinkering I guess, completely removed all plastic and wrap off of the engine harness and inspected it, I was hoping id find an issue but not the case all wires looked serviceable and remarkably flexible still as I was expecting they'd be all hard by now, I reinforced suspected spots that I felt may rub, double checked the pins in the connectors and the ecu, and found nothing to indicate an issue, wife wonders if its not the eco tune it has on and has had for quite sometime. I'm trying to convince her its not, as ive never heard of a tune to cause an intermittent issue like this, usually its either working or not. I also checked the resistance of the injectors to see if maybe the two were overloading the ecu and it would turn off the driver for that injector again to no avail, I got a correct reading across all 4. I also added a large guage ground wire from the harness ground on the firewall to the intake of the engine and have noticed that it idles smoother now, but it may just have been a warmer day today than normal. Also as far as codes go all the injector codes are likely due to me unplugging them to see which cyls failed. usually it just gives a random misfire.

remove ECU and get magnifying glass check pins again

I actually did check them, seemed fine but now I'm reading this, viewtopic.php?f=5&t=78359&start=20 seems exactly what I have. so maybe I wont worry about it

ill take it out for a good drive tomorrow and let yall know, thanks for the help

I had an injector miss on #1 last spring and found I was able to replicate it when I wiggled the bundle of wires coming out of the ECU 1 connector. With the ECU out I could see some blackness on a few of the pins, one of those being for the #1 injector. I ended up actually changing the contacts inside the connector. Been fine since.

Sent from my HTC6525LVW using Tapatalk

_________________
2005 Jeep Liberty CRD Limited
-Timing belt
-Weeks 1 and 2 EGR delete kits

UPDATE---- drove it today for an hour or so and had 0 issues and ontop of that I also enjoyed a nice smooth idle on cold start, which I think I can attribute to the added ground cable. So yay, solved I guess? And Her_crd I suspected that connector from the beginning and actually disassembled it and found that it was in really good condition. I also added some zipties because it didn't have anything holding the wired to the connecter. But I'm fairly certain that it wasn't the issue.

Fingers crossed on your behalf.

_________________
Sold to LOST member my 05 Ltd, GDE Stg II turbo + TCM tune, SunCoast TC w. Transgo kit, Steiger window regulators, Samcos, Fumoto valve, 2nd gen filter head with Lub. Spec. bleeder, Hayden clutch & 11 blade fan, inverted spare, P-1 battery, BF Goodrich Long Trail TAs, Etecno1 glow plugs, timing belt at 50K miles/8 yrs

Poor grounds can cause all kinds of problems and some really strange issues as we have already learned about from other members about the ground behind the left front headlight and the one on the firewall. It might be worth your time to check both of these grounds as well. See pictures below!
I really hope this fixes your issue! Time certainly will tell!

I found a ground problem on my Dodge diesel that only affected transmission OD lockup. Added two extra grounds and it fixed the problem and that was years ago and it has never resurfaced. Found the cure on the Dodge diesel forum! Others were having the same problem.

Also, I was highly skeptical of the communication reset reason as discussed in the other thread! May be true, but I think highly unlikely and implausible!!!

_________________
Supporting Vendor and Moderator of LOST
05 Jeep Liberty CRD Limited
Ironman Springs/Bilstein/Shocks
Yeti StgIV Hot Tune
Week's BatteryTray
No FCV/EGR
Samcos/ProVent
SunCoast/Transgo
Carter Intank-pmp
2mic.Sec.Fuel Filter
Flowmaster/NO CAT
V6Airbox/noVH
GM11 Bld.fan/HDClutch
IronrockArms/wwdieselMount
98 Dodge Cummins 24 Valve

Yeah I hear you there, I think I did have a bad ground before but I added a monster cable from the ground on the firewall to the engine and have noticed that not only does it run smoother but with lights on at night and the dome light on it used to flicker before and now they're solid like you'd expect

One other possibility to ponder: I was having an intermittent problem with injector #1 not firing. Could not figure it out until it got so bad that I needed a tow home. What I found was a few tiny black spots on the #1 injector pins at the ECU. Problem turned out to be "gunk" in the connector on one of the #1 pins. I opened up the connector, slid the offending socket/wire out and cleaned it. Appeared to be covered in clear silicone caulk, like what DCM uses to seal the unused holes in the connector. Some cleaner and a work with a fine pick cleaned it out and have not been bothered since.

I did some checking around, seems that quite a few folks have had issues with intermittent connections with DCM wiring harnesses. It would appear whomever is making these harnesses for DCM, they are being sloppy and it is causing delayed problems down the road.

_________________
2006 KJ CRD