Cerbera 4.2 not running on cylinders 4 & 6
Discussion
This stems from when I replaced the coil packs and HT leads a few weeks back, The coli packs are definitely the right way round, the leads in the correct order and seated correctly on the plugs.
Have now checked whats going on in the exhaust manifold with a laser temperature sensor, cylinders 4 and 6 are not firing at all and 8 not sure about.
I'm now starting to suspect the mini wiring harness between the coil packs and injectors, is it possible to remove and teat a connector (see picture) with a meter with the engine running? or do I need to go the laptop diagnostics route?
Have now checked whats going on in the exhaust manifold with a laser temperature sensor, cylinders 4 and 6 are not firing at all and 8 not sure about.
I'm now starting to suspect the mini wiring harness between the coil packs and injectors, is it possible to remove and teat a connector (see picture) with a meter with the engine running? or do I need to go the laptop diagnostics route?
jamieduff1981 said:
If I were you I'd be switching parts around to see what transposed the problem to other cylinders. It's going to be either the plugs, the leads or that coil pack that's dud.
Agreed I need to have a swapping around session, which I tried before when I hadn't used the heat sensor so could well have been just moving the problem around. To check the spark, remove the plug lead from the suspect cylinder. Fit a spare plug in the lead and lay the plug on the engine so that the hexagonal part is touching the metal part of the engine. Have someone turn the engine over and you should see the spark jumping the tip on a regular basis.
If you have a spark and suspect the injector then a cheap and easy test is this.
Buy a sidelight bulb, the capless one which is a type 501 (12volt 5 watt). Unravel the 2 bare wires and push one into each terminal of the wiring harness plug as in your picture. Turn the engine over and you should see the bulb flash on a regular cycle.
If you have a spark and suspect the injector then a cheap and easy test is this.
Buy a sidelight bulb, the capless one which is a type 501 (12volt 5 watt). Unravel the 2 bare wires and push one into each terminal of the wiring harness plug as in your picture. Turn the engine over and you should see the bulb flash on a regular cycle.
Right, have now tried swapping components around, the cylinders not firing, as confirmed with temperature sensor are 4,6 & 8 which relate to rear coil pack.
Tests:
1. Swapped leads with two from old set.
2. Replaced rear coil pack with one of old coil packs, which were only showing signs of misfire occasionally when hot, so would expect to be fine for this test.
Result:
Both 1 and 2 still resulted in cylinders 4,6 & 8 remaining cold during thermometer test while others rapidly heated up as expected, it also worth mentioning again that when I pulled all the plugs and examined 4 & 6 (central pair on drivers side) were wet with fuel which makes me think its not an injector fault.
When I first fitted the new coil packs I mounted the rear one the same way round as the front which resulted in a loud pop from the engine compartment, the firing cycle for that one would have been the wrong way round, so looks like I have fried not the rear coli pack, but something electrical, maybe the ECU is confused and just needs resetting? What else could it be?!!!
Tests:
1. Swapped leads with two from old set.
2. Replaced rear coil pack with one of old coil packs, which were only showing signs of misfire occasionally when hot, so would expect to be fine for this test.
Result:
Both 1 and 2 still resulted in cylinders 4,6 & 8 remaining cold during thermometer test while others rapidly heated up as expected, it also worth mentioning again that when I pulled all the plugs and examined 4 & 6 (central pair on drivers side) were wet with fuel which makes me think its not an injector fault.
When I first fitted the new coil packs I mounted the rear one the same way round as the front which resulted in a loud pop from the engine compartment, the firing cycle for that one would have been the wrong way round, so looks like I have fried not the rear coli pack, but something electrical, maybe the ECU is confused and just needs resetting? What else could it be?!!!
Erich Stahler said:
Right, have now tried swapping components around, the cylinders not firing, as confirmed with temperature sensor are 4,6 & 8 which relate to rear coil pack.
Tests:
1. Swapped leads with two from old set.
2. Replaced rear coil pack with one of old coil packs, which were only showing signs of misfire occasionally when hot, so would expect to be fine for this test.
Result:
Both 1 and 2 still resulted in cylinders 4,6 & 8 remaining cold during thermometer test while others rapidly heated up as expected, it also worth mentioning again that when I pulled all the plugs and examined 4 & 6 (central pair on drivers side) were wet with fuel which makes me think its not an injector fault.
When I first fitted the new coil packs I mounted the rear one the same way round as the front which resulted in a loud pop from the engine compartment, the firing cycle for that one would have been the wrong way round, so looks like I have fried not the rear coli pack, but something electrical, maybe the ECU is confused and just needs resetting? What else could it be?!!!
Bouncing this, really just need to know if the factory laptop software can reset the ECU as I thing running one of the coil packs the wrong way round might have confused it?Tests:
1. Swapped leads with two from old set.
2. Replaced rear coil pack with one of old coil packs, which were only showing signs of misfire occasionally when hot, so would expect to be fine for this test.
Result:
Both 1 and 2 still resulted in cylinders 4,6 & 8 remaining cold during thermometer test while others rapidly heated up as expected, it also worth mentioning again that when I pulled all the plugs and examined 4 & 6 (central pair on drivers side) were wet with fuel which makes me think its not an injector fault.
When I first fitted the new coil packs I mounted the rear one the same way round as the front which resulted in a loud pop from the engine compartment, the firing cycle for that one would have been the wrong way round, so looks like I have fried not the rear coli pack, but something electrical, maybe the ECU is confused and just needs resetting? What else could it be?!!!
Erich Stahler said:
Bouncing this, really just need to know if the factory laptop software can reset the ECU as I thing running one of the coil packs the wrong way round might have confused it?
It depends what you mean by "reset". Yes the adaptive maps can be reset by the software - there isnt really anything else to reset as that is the only statefull data it stores dynamicaly. The ECU is going to be unaware of which way round the coil packs are connected and couldn't care less anyway, so it is not going to have been "confused" by it. Just thinking - have you been testing temperatures at idle or after a good run? If you are testing at idle, is it possible you upset the throttle balance between the left and right banks during the work? Either the adjustment for the throttle butterflys, or you've could have leaned on the throttle pot during the work and moved it?
Give it some beans on the road - if you have 3 cylinders out it will run like a dog, if however it still puts a smile on your face, then check the idle on right hand bank.
Give it some beans on the road - if you have 3 cylinders out it will run like a dog, if however it still puts a smile on your face, then check the idle on right hand bank.
xia245 said:
Just thinking - have you been testing temperatures at idle or after a good run? If you are testing at idle, is it possible you upset the throttle balance between the left and right banks during the work? Either the adjustment for the throttle butterflys, or you've could have leaned on the throttle pot during the work and moved it?
Give it some beans on the road - if you have 3 cylinders out it will run like a dog, if however it still puts a smile on your face, then check the idle on right hand bank.
You can disconnect one throttle pot and the ecu defaults to run both banks on the one. Give it some beans on the road - if you have 3 cylinders out it will run like a dog, if however it still puts a smile on your face, then check the idle on right hand bank.
I have just run the engine again with a transparent ht lead connector to visually check the spark, on the suspect cylinder there is a very feint spark compared to a very bright one on the only good cylinder on that bank, repeated again with different lead and same result. Basically whichever coil pack or lead combination I use the same cylinders on that bank are getting almost no spark, so it must be in the low tension loom or the ecu?
Erich Stahler said:
I have just run the engine again with a transparent ht lead connector to visually check the spark, on the suspect cylinder there is a very feint spark compared to a very bright one on the only good cylinder on that bank, repeated again with different lead and same result. Basically whichever coil pack or lead combination I use the same cylinders on that bank are getting almost no spark, so it must be in the low tension loom or the ecu?
I can now confirm its definitely an HT problem, tested with transparent plug cap, the cylinders in question show very slight spark, almost nothing compared to a good bright spark on ones that are running, regardless of which plug leads or coil packs I swap around. So how do I test the lead that plugs into the coil pack for the RHS bank of cylinders?
Sounds like your going to have to check resistance on the wiring from the coil pack back to the pins on the ecu plug.
The wiring diagram I have looked at shows pins 1 and 2 on the coil pack connectors running back to pins 19 and 20 on the engine ecu for the Even cylinder coil pack and pins 1 and 2 on the odd coil pack running back to pins 40 and 55. The coils are supplied by a fused 12V ignition feed to either pin 3 or 4 or both as the coil pack is linked internally between the 2 pins, on the citroen and Peugeot applications pin 3 or 4 is sometimes used for noise suppression with a capacitor.
The pin 1 and 2 of the coil packs are earthed by the engine ecu to make a pair of leads fire, i.e. the coil pack is split in to 2 pairs, pin 1 earths the one side firing one pair and pin 2 earths the other side firing the other pair.
If it was working before then it is likely that you have wires that have broken or breaking in the loom where it has been moved to change the coils, if the misfire was intermittent before this could also be the cause of your misfires the wires making and breaking rather than a duff coil pack.
Hope you get it sorted soon.
The wiring diagram I have looked at shows pins 1 and 2 on the coil pack connectors running back to pins 19 and 20 on the engine ecu for the Even cylinder coil pack and pins 1 and 2 on the odd coil pack running back to pins 40 and 55. The coils are supplied by a fused 12V ignition feed to either pin 3 or 4 or both as the coil pack is linked internally between the 2 pins, on the citroen and Peugeot applications pin 3 or 4 is sometimes used for noise suppression with a capacitor.
The pin 1 and 2 of the coil packs are earthed by the engine ecu to make a pair of leads fire, i.e. the coil pack is split in to 2 pairs, pin 1 earths the one side firing one pair and pin 2 earths the other side firing the other pair.
If it was working before then it is likely that you have wires that have broken or breaking in the loom where it has been moved to change the coils, if the misfire was intermittent before this could also be the cause of your misfires the wires making and breaking rather than a duff coil pack.
Hope you get it sorted soon.
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