Alloytec Random multiple misfire cyl 1,3,5,

[Relax98]

Hi all, I understand this is a VZ section, but was hoping someone may have a solution to my issue.
My in laws car 08 Ve alloytec has came up with p0300 random misfire fault, also cylinders 1, 3, 5. RACV told them that two coils were gone and had to be replaced. So I got the job to replace them, only to find fault still comes up. I put 2 new coils into 1 & 2 fitted 2 into 3 and swapped 4 with 5, the fault still did not change. I also checked the spark plus and they all seem fine NGK platinums so I assume they have been changed. The car has 153000 on the clock. It has also had the right side cat changed for a previous fault, one O2 sensors also for another fault. I have tried searching posts on this but haven't been able to find a solution. The car starts fine every time but once revved over 2000 the miss comes back and the left bank is shut down. So after some more investigation tonight I found a vac leak coming from 90 degree fitting at the rear of the drivers side valve cover. The hose goes to a tee then one hose to each side of the plenum. I blocked these off but found no difference, I didn't expect to but worth a try. I then plugged in my code reader and reset the fault and noticed some variations between STFL B1 12.5% and STFL B2 6.25% average fluctuating but B1 always higher.
I also noticed differences with the O2 readings, o2s 11 0.360v -14.85%, o2s 12 0.465v 99.21%, o2s 21 0.690v 11.71%, o2s 22 0.480v 99.21%. Not sure if this info is of any use but may mean something to someone clever on here. Any help appreciated, It is about to be sent to holden to see what they say. $$$$$ hopefully not.

 

[madute]

Hi all, I understand this is a VZ section, but was hoping someone may have a solution to my issue.
My in laws car 08 Ve alloytec has came up with p0300 random misfire fault, also cylinders 1, 3, 5. RACV told them that two coils were gone and had to be replaced. So I got the job to replace them, only to find fault still comes up. I put 2 new coils into 1 & 2 fitted 2 into 3 and swapped 4 with 5, the fault still did not change. I also checked the spark plus and they all seem fine NGK platinums so I assume they have been changed. The car has 153000 on the clock. It has also had the right side cat changed for a previous fault, one O2 sensors also for another fault. I have tried searching posts on this but haven't been able to find a solution. The car starts fine every time but once revved over 2000 the miss comes back and the left bank is shut down. So after some more investigation tonight I found a vac leak coming from 90 degree fitting at the rear of the drivers side valve cover. The hose goes to a tee then one hose to each side of the plenum. I blocked these off but found no difference, I didn't expect to but worth a try. I then plugged in my code reader and reset the fault and noticed some variations between STFL B1 12.5% and STFL B2 6.25% average fluctuating but B1 always higher.
I also noticed differences with the O2 readings, o2s 11 0.360v -14.85%, o2s 12 0.465v 99.21%, o2s 21 0.690v 11.71%, o2s 22 0.480v 99.21%. Not sure if this info is of any use but may mean something to someone clever on here. Any help appreciated, It is about to be sent to holden to see what they say. $$$$$ hopefully not.

I'm no expert but the last time a mate had an issue like this it was a bad injector was clogged.

 

[diysv6]

Hi all, I understand this is a VZ section, but was hoping someone may have a solution to my issue.
My in laws car 08 Ve alloytec has came up with p0300 random misfire fault, also cylinders 1, 3, 5. RACV told them that two coils were gone and had to be replaced.

I have a 2004 Alloytec so the locations could be the same in the VE, but then again Holden may have configured the earthing in a different manner.

So this is the 2004 Alloytec offering.

The earth returns for the ignition coils for cylinders 1,3, and 5 are commoned together and bolted to an earth point on the outside rear of the odd cylinder head. If the fault is unlocatable then look at the wiring carrier which runs on the outside top edge of the cylinder head. Out of the carrier will come the ignition coils connectors etc. Also out of the carrier is a wire going to an earth bolt at the rear of the cylinder head. I had checked mine when my ECU was failing. The earths are commoned up inside the carrier and a double wire from memory goes to the earth location. If the lug crimp, terminal bond to the aluminium head is corroded then the coils could fire erratically with engine/exhaust temperature changes, vibration, water splash access etc. Do they use an aggressive high pressure engine degreaser at all?

Similarly the cylinders 2,4 and 6 coils are earthed on the other cylinder head to the rear of the oil filter housing.

I hope this may help if you get nowhere with the fault.

 

[Relax98]

Thanks Diy I will check the earth point, there is one towards the front of the drivers side bank, last service notes did mention engine de-grease / clean. I will be sure to post when I get a possitive outcome.

 

[Relax98]

Cleaned earth points ( 3 ) along bank 1. no change. Holden mechanic suggested injectors so I have changed from one bank to the other... no change.. I am starting to think it may have something to do with the ECU anyway back to Holden on tuesday, I will post the outcome.

 

[Ve2007jf]

Hi, did you ever find out what the problen was cause i too am having a similar problem, i thought it could have been stretched timing chains and replaced them myself using a workshop manual, but it didn't change a thing, still coming up with faults on one bank of cylinders

 

[Benboy]

If you or a family member are paid up Auto Club members, make a call and get them to send a 'mobile mechanic' for an opinion. Most Auto Clubs also offer a diagnostic service (for a nominal fee). Perhaps for the cost of membership you might consider that as an option. Might turn out to be a lot cheaper. Holden Dealers know how to charge !!

 

[Trax 211]

A very common fault with the alloytec engine which creates a whole bank misfire is a sticking vct actuator solinoid. Depending on the engine some have 2 per head or only 1 for each head. They are bolted in the front of the head using a 10mm headed bolt. Try swapping them from left head to the right. When they are removed check the gauze and make sure they look clean. If the misfire changes banks you know what the culprit is. The issue is that they will open under high oil pressure/higher revs but can't close when the revs drop due to carbon deposits in fine tolerance components creating a valve timing issue and misfire due to camshaft not returning to the correct position.

 

[wraith73]

I've got an issue with my father in law's VZ. Used to 'splutter' a bit at around 80kmh. Over the last couple days, on acceleration, the check drivetrain warning came up and it started running like a Ford. Barely stayed running at idle, and takeoff slow and rough. Connected up a real time scanner, which came up with codes P0300, 304 & 306. While idling and going thru codes, i hit wrong button on the scanner, and erased codes. Immediately, the car idled perfectly smooth with no faults. The faults eventually came back, but each time, she ran fine as soon as I pressed erase. Seemed a bit odd to me. All the wiring and connections, as per other posts, seem fine. All I've done recently is add a tin of injector cleaner (Liqui-Moly). He's hoping to sell the car, but can't really do anything until these issues are fixed.

 

[Big Red VF-SII Go-kart]

A very common fault with the alloytec engine which creates a whole bank misfire is a sticking vct actuator solinoid. Depending on the engine some have 2 per head or only 1 for each head. They are bolted in the front of the head using a 10mm headed bolt. Try swapping them from left head to the right. When they are removed check the gauze and make sure they look clean. If the misfire changes banks you know what the culprit is. The issue is that they will open under high oil pressure/higher revs but can't close when the revs drop due to carbon deposits in fine tolerance components creating a valve timing issue and misfire due to camshaft not returning to the correct position.

That's interesting. Very, very interesting.