P2311 DTC....need input.

[smallcrimes]

So, my 2005 Liberty (3.7) is currently throwing a P2311 DTC my way, and it's symptoms are rough idle and bucking in every gear when the engine speed hits right around 2k RPMs. As you can imagine, this makes for a terrible ride and lots of pissed off people who happen to land behind me at a light when it's time for take off.

Anyway, I typed out a whole thing about what I've done so far in testing and I think I've pretty well whittled down what the issue is - but if you have the time, and actually read what I've written/done AND you have some input or experience close to this, your input would be greatly appreciated. Especially if it can save me from doing something rash....

**Rough idle and driving through all gears, MIL on with DTC P2311 of concern, vehicle ‘bucking’ in every gear with engine RPMs @ or around 2k; cursory knowledge indication of #4 coil malfunction – situation preceded by intermittent P0300 DTCs**

• Testing performed with all coils/fuel injectors/cylinders in mind:
 All coils and fuel injectors metered for impedance within spec (all coils primary resistance within . 6Ω - .9Ω & secondary resistances between 7.25 kΩ-8.84 kΩ. Fuel injectors all tested right around 12-13Ω)
 All fuses and relays in related circuits tested/verified
 All connections inspected and verified as secure
 Grounding straps tested with no voltage drops
 All plugs recently replaced and gapped to vehicle’s EPA information (.040); at onset of recent symptoms, all plugs were pulled and inspected – all had virtually no real wear, except on #4, which had heavy carbon deposits.
 Fuel pump relay removed and all coils individually tested for spark. All had good, healthy spark, with the exception being #4

• Testing performed to specific coils:
 Coil #1
Metered for continuity between ASD relay out on 87, and supply at coil (Rd/Org), as well as continuity between PCM and the signal wire (YL/DB – pin 1 at coil connector, C2/pin 10 at PCM).
Supply tests @ 14.3vDC with engine running.
Signal wire tests @ 2.36vAC/.707vAC min/max.
 Coil #2
Metered for continuity between ASD relay out on 87, and supply at coil (Rd/Org), as well as continuity between PCM and the signal wire (DB/YL – pin 1 at coil connector, C2/pin 9 at PCM).
Supply tests @ 14.3vDC with engine running.
Signal wire tests @ 2.43vAC/.716vAC min/max.
 Coil #3
Metered for continuity between ASD relay out on 87, and supply at coil (Rd/Org), as well as continuity between PCM and the signal wire (DB – pin 1 at coil connector, C2/pin 7 at PCM).
Supply tests @ 14.3vDC with engine running.
Signal wire tests @ 2.47vAC/.727vAC min/max.
 Coil #4
Metered for continuity between ASD relay out on 87, and supply at coil (Rd/Org), as well as continuity between PCM and the signal wire (DB – pin 1 at coil connector, C2/pin 3 at PCM).
Supply tests @ 14.3vDC with engine running.
Signal wire tests @ 152.9mVAC/128.7mVAC min/max
 Coil #5
Metered for continuity between ASD relay out on 87, and supply at coil (Rd/Org), as well as continuity between PCM and the signal wire (DB/YL – pin 1 at coil connector, C2/pin 2 at PCM).
Supply tests @ 14.3vDC
Signal wire tests @ 2.39vAC/.707vAC min/max
 Coil #6
Metered for continuity between ASD relay out on 87, and supply at coil (Rd/Org), as well as continuity between PCM and the signal wire (DB/OR – pin 1 at coil connector, C2/pin 1 at PCM).
Supply wire tests @ 14.3vDC with engine running.
Signal wire tests @ 2.41vAC/.712vAC min/max.



With all this information in mind, I determined that the problem lies with the fact that the coil on #4 is just not getting the signal it needs for spark. Just to rule it out, and even though it tested fine for continuity, I did run a new wire from the PCM to the connector at #4. Unfortunately that amounted to nothing, and I have to believe that there must be a problem with the PCM itself. Without knowledge of the interior layout of the PCM, or whether or not there may be isolated corrosion, etc. on only one part of the internal board (pins and receiving cavs on connector appear fine)- the question seems to be, “Why would the PCM send a weak signal on only one pin and have no indication of failure for the others?” I’m left wondering what conditions would cause this.

Now, I've been told by a friend who runs a shop that I maaaaay have to just get the PCM reflashed. The cheapest I can get that done for around here is at $175 pricetag, which is just anklegrabbin' mode as far as I'm concerned. The only other option I've debated trying is one of those "hey, we'll send you a new/refurbished PCM flashed to your exact mileage and VIN" places, but that sounds shady AF and I couldn't afford to not drive my liberty for however long it takes to come in the mail (considering the ODO).

Anyway, if anyone's made it though this I applaud you. If you've had this same problem. I'm sorry. If you have an answer that I may find more on terms with my cheapskate outlook on life....I might have to send you a bottle of something.

Thanks, whatever way this finds you.

-D

 

[Billwill]

So, my 2005 Liberty (3.7) is currently throwing a P2311 DTC my way, and it's symptoms are rough idle and bucking in every gear when the engine speed hits right around 2k RPMs. As you can imagine, this makes for a terrible ride and lots of pissed off people who happen to land behind me at a light when it's time for take off.

Anyway, I typed out a whole thing about what I've done so far in testing and I think I've pretty well whittled down what the issue is - but if you have the time, and actually read what I've written/done AND you have some input or experience close to this, your input would be greatly appreciated. Especially if it can save me from doing something rash....

**Rough idle and driving through all gears, MIL on with DTC P2311 of concern, vehicle ‘bucking’ in every gear with engine RPMs @ or around 2k; cursory knowledge indication of #4 coil malfunction – situation preceded by intermittent P0300 DTCs**

• Testing performed with all coils/fuel injectors/cylinders in mind:
 All coils and fuel injectors metered for impedance within spec (all coils primary resistance within . 6Ω - .9Ω & secondary resistances between 7.25 kΩ-8.84 kΩ. Fuel injectors all tested right around 12-13Ω)
 All fuses and relays in related circuits tested/verified
 All connections inspected and verified as secure
 Grounding straps tested with no voltage drops
 All plugs recently replaced and gapped to vehicle’s EPA information (.040); at onset of recent symptoms, all plugs were pulled and inspected – all had virtually no real wear, except on #4, which had heavy carbon deposits.
 Fuel pump relay removed and all coils individually tested for spark. All had good, healthy spark, with the exception being #4

• Testing performed to specific coils:
 Coil #1
Metered for continuity between ASD relay out on 87, and supply at coil (Rd/Org), as well as continuity between PCM and the signal wire (YL/DB – pin 1 at coil connector, C2/pin 10 at PCM).
Supply tests @ 14.3vDC with engine running.
Signal wire tests @ 2.36vAC/.707vAC min/max.
 Coil #2
Metered for continuity between ASD relay out on 87, and supply at coil (Rd/Org), as well as continuity between PCM and the signal wire (DB/YL – pin 1 at coil connector, C2/pin 9 at PCM).
Supply tests @ 14.3vDC with engine running.
Signal wire tests @ 2.43vAC/.716vAC min/max.
 Coil #3
Metered for continuity between ASD relay out on 87, and supply at coil (Rd/Org), as well as continuity between PCM and the signal wire (DB – pin 1 at coil connector, C2/pin 7 at PCM).
Supply tests @ 14.3vDC with engine running.
Signal wire tests @ 2.47vAC/.727vAC min/max.
 Coil #4
Metered for continuity between ASD relay out on 87, and supply at coil (Rd/Org), as well as continuity between PCM and the signal wire (DB – pin 1 at coil connector, C2/pin 3 at PCM).
Supply tests @ 14.3vDC with engine running.
Signal wire tests @ 152.9mVAC/128.7mVAC min/max
 Coil #5
Metered for continuity between ASD relay out on 87, and supply at coil (Rd/Org), as well as continuity between PCM and the signal wire (DB/YL – pin 1 at coil connector, C2/pin 2 at PCM).
Supply tests @ 14.3vDC
Signal wire tests @ 2.39vAC/.707vAC min/max
 Coil #6
Metered for continuity between ASD relay out on 87, and supply at coil (Rd/Org), as well as continuity between PCM and the signal wire (DB/OR – pin 1 at coil connector, C2/pin 1 at PCM).
Supply wire tests @ 14.3vDC with engine running.
Signal wire tests @ 2.41vAC/.712vAC min/max.



With all this information in mind, I determined that the problem lies with the fact that the coil on #4 is just not getting the signal it needs for spark. Just to rule it out, and even though it tested fine for continuity, I did run a new wire from the PCM to the connector at #4. Unfortunately that amounted to nothing, and I have to believe that there must be a problem with the PCM itself. Without knowledge of the interior layout of the PCM, or whether or not there may be isolated corrosion, etc. on only one part of the internal board (pins and receiving cavs on connector appear fine)- the question seems to be, “Why would the PCM send a weak signal on only one pin and have no indication of failure for the others?” I’m left wondering what conditions would cause this.

Now, I've been told by a friend who runs a shop that I maaaaay have to just get the PCM reflashed. The cheapest I can get that done for around here is at $175 pricetag, which is just anklegrabbin' mode as far as I'm concerned. The only other option I've debated trying is one of those "hey, we'll send you a new/refurbished PCM flashed to your exact mileage and VIN" places, but that sounds shady AF and I couldn't afford to not drive my liberty for however long it takes to come in the mail (considering the ODO).

Anyway, if anyone's made it though this I applaud you. If you've had this same problem. I'm sorry. If you have an answer that I may find more on terms with my cheapskate outlook on life....I might have to send you a bottle of something.

Thanks, whatever way this finds you.

-D

I have seen a similar post to this before on one of the KJ forums...opening up the PCM showed some burnt out components...probably power transistors or SCrs......corresponding to the coil circuits that were failing. In this particular case the owner had first swapped coils over and wherever the bad coil went...it blew the related SCR!

Worth while carefully opening the PCM and look for obvious damage and if you do see a blown component obviously try find the cause of the short before replacing the PCM!

 

[smallcrimes]

Thanks for the insight, good sir. And, believe me, I was super thorough to make sure there weren't any wires kissing each other along the way. Also, like I said, all coil packs tested fine....so, no bad ones. As far as yanking the PCM to crack her open - I tried, and almost immediately admitted defeat.

Took out the T-15s which, at first blush, seemed to be the only thing holding me back. Then, it just looked like it should slide apart (which it, of course, does not). At that, I noticed what seemed to be lock grooves running along the left hand side and across the top horizontal - so I figured, slide it slightly sideways and then out......but nothing would budge.

I don't know if it was just crudded up, but the housing seems like ****** white metal and I'm not sure if everything's siliconed up in there (to immediately destroy and guard against prying eyes) so I didn't screw with it too much more after that.

So, now I'm just looking at quotes from one shop (the cheapest)that sends out units to be repaired or replaced - they're quoting me a minimum of $250 to be the middle man and have this third party company do some diagnostics on it. At that point, I'm told, it would be another $75-$100 for repair....OR, if it's completely boned and unrecoverable, I'd have to purchase a new/refurb one and have it flashed at a dealership.

On the other hand, since Christmas is already looking like shit for the fam, and I'm not too worried about wasting any more money, this place claims to be able to flash a refurbed one to my exact VIN and ODO, without anymore servicing needed......and all for $159!! But, again.....shady as hell. I dunno anymore.

 

[Billwill]

Thanks for the insight, good sir. And, believe me, I was super thorough to make sure there weren't any wires kissing each other along the way. Also, like I said, all coil packs tested fine....so, no bad ones. As far as yanking the PCM to crack her open - I tried, and almost immediately admitted defeat.

Took out the T-15s which, at first blush, seemed to be the only thing holding me back. Then, it just looked like it should slide apart (which it, of course, does not). At that, I noticed what seemed to be lock grooves running along the left hand side and across the top horizontal - so I figured, slide it slightly sideways and then out......but nothing would budge.

I don't know if it was just crudded up, but the housing seems like ****** white metal and I'm not sure if everything's siliconed up in there (to immediately destroy and guard against prying eyes) so I didn't screw with it too much more after that.

So, now I'm just looking at quotes from one shop (the cheapest)that sends out units to be repaired or replaced - they're quoting me a minimum of $250 to be the middle man and have this third party company do some diagnostics on it. At that point, I'm told, it would be another $75-$100 for repair....OR, if it's completely boned and unrecoverable, I'd have to purchase a new/refurb one and have it flashed at a dealership.

On the other hand, since Christmas is already looking like shit for the fam, and I'm not too worried about wasting any more money, this place claims to be able to flash a refurbed one to my exact VIN and ODO, without anymore servicing needed......and all for $159!! But, again.....shady as hell. I dunno anymore.

Have you physically measured the failing #4 signal wire for continuity and for a short or partial short to ground or anywhere else?

Best is to disconnect that #4 signal lead completely on both ends (Dark Blue/Red wire I think) and measure for any continuity to ground. You can also leave that wire completely disconnected and replace it with a new lead as a temporary check.

Also check the PCM contacts are clean.

 

[AVR2]

this place claims to be able to flash a refurbed one to my exact VIN and ODO, without anymore servicing needed......and all for $159!! But, again.....shady as hell. I dunno anymore.

Just as a heads-up (if you didn't already know), there is at least one company in the south-eastern USA selling refurb ECUs that you're advised not to touch with a ten-foot pole. Numerous Jeepers (and owners of other makes) have cautionary stories to tell about dealing with them. A bit of Googling will help you out with more specific information.

 

[smallcrimes]

Have you physically measured the failing #4 signal wire for continuity and for a short or partial short to ground or anywhere else?

Best is to disconnect that #4 signal lead completely on both ends (Dark Blue/Red wire I think) and measure for any continuity to ground. You can also leave that wire completely disconnected and replace it with a new lead as a temporary check.

Also check the PCM contacts are clean.

Yeah, at the point I'd first written that, I had actually done a couple things: 1. Disconnected at the PCM and the coil to test continuity straight through. 2. Tested from both ends, in a few different positions, to see if it was getting some lovin' from ground.....no dice. 3. Cut the bastard about six inches from each connector (knowing a chimp can repair wiring.....and I'm slightly smarter than one) and ran new wiring from connector to connector....got comparable readings, telling me the PCM is just telling me to eat shit.

Now fast forward to today: I'm getting failing readings on four out of six cylinders. I'm doing financially-irreparable damage to my engine, as it's my only vehicle.....can't afford a meantime junker and I still need to feed my family.

Tax refunds can't come soon enough.

 

[bill.wellington]

exact same issue on cyl 6

my 06 liberty just started bucking at 2200 rpm. after getting home, which was close, it wont go above 2200 rpm then drops to 2000 and just keeps going back a forth. fault code p2317 ignition coil F secondary circuit. i basically checked everything you did exept coil connector to asd relay but im sure its the same isssue. i changed out the camshaft pos sensor and crankshaft pos sensor plus new plugs. swapped coils around after testing them. even swapped injectors incase the pcm needed the permissive from it before grounding the signal wire. the constant voltage is there but not spark. while running the signal wire ohms to ground 1500-1800ohms while no other coil connector does.

did you have any luck with a new PCM? im thinking of getting one from allcomputerresources.com

 

[mightybeet]

i started to get P2311 this past weekend with similar conditions with intermittent misfires occurring at:
- 2k+ rpm
- over 40+ mph
- under load/uphill/speeding up on highway

i took the coil off of #4 and saw nice black mark on the inside of the coil boot(i ll take a pic). i swopped coils with #3 and started to get codes P2308 and a bonus P0303 on #3. so that solved it.

but my wondering is why #4 arcing?... one thought i had was the overflow hose to reservoir was leaking coolant right on to the connector of #4. no signs of issue in the connector. i ll have to check again to see if any coolant ran down the coil. who knows...

another thought was... when was the last time i changed the plugs?

 

[uss2defiant]

i started to get P2311 this past weekend with similar conditions with intermittent misfires occurring at:
- 2k+ rpm
- over 40+ mph
- under load/uphill/speeding up on highway

i took the coil off of #4 and saw nice black mark on the inside of the coil boot(i ll take a pic). i swopped coils with #3 and started to get codes P2308 and a bonus P0303 on #3. so that solved it.

but my wondering is why #4 arcing?... one thought i had was the overflow hose to reservoir was leaking coolant right on to the connector of #4. no signs of issue in the connector. i ll have to check again to see if any coolant ran down the coil. who knows...

another thought was... when was the last time i changed the plugs?

I would think the boot on the top and bottom would prevent water from reaching the spark plug. Also, if you put anti-seize on the threads I would think it would be hard for coolant to reach the combustion area.

Have the ignition coil bubbled up on the sides?

 

[mightybeet]

4 started misfiring again so pulled the plug. there was a black mark on the ceramic similar to the boot. corrosive stains only on the ceramic side. plug gap was huge. new coil and plug. idles and runs nicer. if it wasnt so fracking windy i would have changed all. soon as i removed the coil a little leave flies right into the coil chamber... jerk.

 

[MarkJ]

Well, if it is a bad coil causing the components inside the PCM to fail, then don't get a new PCM until you change the bad coil as well.
Mark

 

[2005kj_verhelle]

Did you ever find the cause? Just bought a 2005 Liberty with almost this same exact issue. Great detail in the write up above.

Thanks
Aaron

 

[2005kj_verhelle]

You must be registered for see images attach

Opened my PCM and found a burnt chip, going to assume that was your issue, too.