VZ V6 Alloytech running extreamly rough - not driveable

[TAHAIC]

Hi, I need help from the experts out there. About a month ago I pulled the timer cover off due to an oil leak near the alternator, I replaced the water pump, thermostat housing complete and front water pipe seals while I was at it. Also replaced rocker cover gaskets and full set of injectors, spark plugs and even lower and upper inlet gaskets. It was running perfect - better than ever for about 3 weeks and then as I was driving to the petrol station (fuel was low but didn't run out) it started running really rough. I though I ran out of fuel it was so bad but I didn't and I fuel in it and it was still running rough. It's really bad like its misfiring on 1 or 2 cylinders buts its not misfiring - its so bad I cant drive it, it will idle but really rough and when I drive it sill really rough and no power at all. I have a OBDII USB connector and some basic software on my laptop to check and clear errors and it has no error codes logged or pending. I pulled the plenum of this morning thinking that it may be sucking air - the gaskets did look a little doggy despite only being new so I put the old gaskets back on but its made no difference. I can't imagine that the lower inlet gasket is the problem since its new but I guess it could be.

I disconnected the MAF plug and it made no difference in idle which was a little interesting. I checked MAF values with OBDII and it was responding to accelerator indicating to me that the MAF was working.

Has anyone got any ideas or had this type problem before with this motor LE0 175kW? I'm at a loss as to what it could be and would really appreciate some help.

Sorry if its been posted before but I searched and could only find posts where people had errors pointing to coil packs, spark plugs and such which I don't have.

 

[diysv6]

Have some possible suggestions. Hope they may help.
You may need a better grade of diagnostic tool. The Holden Tech2 is the best. SCA stores have a Bosch analyser they can connect up to see the DTCs etc.


Can you sequentially disconnect/reconnect each ignition coil's power connector and see which plug does not affect the idle.
Then I would check the coil/plug and injector.
Have you disturbed the earth point on each cylinder head? The earth is required for the ignition coils to correctly function.

Is your fuel filter replaced recently? Is fuel pressure correct?

Is the throttle body connector homed properly and the locking lever correctly set? The connector body can crack and not keep good connections.

The MAF/IAT Sensor is a combination temperature and mass airflow sender in the 190kw motor. Is the connector correctly in place and the connections clean?

If you had disconnected the fuel injector power connector at rear of the motor, is that set correctly.
Can you get a piece of dowel and listen to the fuel injectors clicking?

Did you unplug the two big connectors on the ECU. (Check the ECU earth wire I think there is one there). Are they seated correctly and the locking levers in place?

Your O2 sensors have not been disturbed in the wiring connectors on each cylinder head?

Your power brake unit one-way valve/hose connection are not split etc?

The vacuum line to the EVAP solenoid is not split damaged at the throttle body or not connected at the EVAP end?


I don't know what to expect if you have a dirty connector which senses crankshaft and camshaft positions etc. Have not played in this area.

Other knowledgeable members can probably reflect on those issues.

 

[TAHAIC]

You may need a better grade of diagnostic tool. The Holden Tech2 is the best. SCA stores have a Bosch analyser they can connect up to see the DTCs etc.

Its not the best but it does seem to report errors correctly and let me clear them.

Can you sequentially disconnect/reconnect each ignition coil's power connector and see which plug does not affect the idle.
Then I would check the coil/plug and injector.

I haven't done this because I don't have any misfire fault codes. Is there any risk of damaging the ignition module if disconnecting these with the car running?

Have you disturbed the earth point on each cylinder head? The earth is required for the ignition coils to correctly function.

I made sure the earths had good connections, I am an Electrician so I pay particular attention to such details. The car was running like a dream for about 3 weeks until now and something of that nature would have been evident before.

Is your fuel filter replaced recently?

I just replaced it yesterday - wasn't the problem but good to change it anyway.

Is fuel pressure correct?

I don't know, how can I check this? It is possible that the fuel pump is failing since it was low on fuel when it started happening.

Is the throttle body connector homed properly and the locking lever correctly set? The connector body can crack and not keep good connections.

Yes it seems seated correctly and locking lever is set. No apparent cracking.

The MAF/IAT Sensor is a combination temperature and mass airflow sender in the 190kw motor. Is the connector correctly in place and the connections clean?

Yes connection good. Like I said I am getting response when I check with laptop but oddly it makes absolutely no difference to the rough idle when I disconnect it. I would expect it to get worse and even stall. It throws codes when I disconnect it and I have cleared them.

If you had disconnected the fuel injector power connector at rear of the motor, is that set correctly.

Yes checked it.

Can you get a piece of dowel and listen to the fuel injectors clicking?

Can not access due to plenum - unless you know a trick that I don't in how to get in there.

Did you unplug the two big connectors on the ECU. (Check the ECU earth wire I think there is one there). Are they seated correctly and the locking levers in place?

Yes I did disconnect but they are plugged in correctly - again the car has been running perfectly for 3 weeks or so.

Your O2 sensors have not been disturbed in the wiring connectors on each cylinder head?

No O2 error codes - connections are ok. O2 sensors will cause excessive fuel consumption but in my experience won't cause rough running like this.

Your power brake unit one-way valve/hose connection are not split etc?

Yes seems good, vacuum lines is the first thing I checked.

The vacuum line to the EVAP solenoid is not split damaged at the throttle body or not connected at the EVAP end?

Seems good.

I don't know what to expect if you have a dirty connector which senses crankshaft and camshaft positions etc. Have not played in this area.
Other knowledgeable members can probably reflect on those issues.

I had one fail on my old VK and it wouldn't start at all but I don't know how they effect VZ - I would expect error codes also.

Thanks for your help I really appreciate it. Please keep the support comming

I'm thinking I am gonna have to take the inlet manifold off again and check the bottom gasket.

 

[diysv6]

I haven't done this because I don't have any misfire fault codes. Is there any risk of damaging the ignition module if disconnecting these with the car running?


I have disconnected the power connectors to the coils while the engine runs with no ill effects. A faulty coil does not necessarily give a fault code if the problem is in the EHT side of the unit. Some after market ignition coils have been found to be faulty after being in service a short time, some even becoming smokey and catch fire.

http://forums.justcommodores.com.au/vz-holden-commodore-2004-2006/249126-coil-pack.html

Did you reverse flush the fuel filter to see if there was much sludge in the filter?



I don't know, how can I check this? It is possible that the fuel pump is failing since it was low on fuel when it started happening.

If the fuel line picked up rubbish and some got through into the injector/s, then maybe one or two injectors are fouled and not delivering proper metering of fuel.

The Tech 2 is able to do a test which tests the flow volumes of each injector by using a fuel pressure meter and logging the fuel line pressure after a certain number of coil's firing sequences. The fuel pressure gauge will also allow you to see if your fuel injectors are leaking down with the ignition Off.
Pressure gauges are about $40 -$50 each. I bought a cheaper unit of ebay for about $40 when my problems were evident. The gauge gave a certain peace of mind during my fault finding.


Yes connection good. Like I said I am getting response when I check with laptop but oddly it makes absolutely no difference to the rough idle when I disconnect it. I would expect it to get worse and even stall. It throws codes when I disconnect it and I have cleared them.

Did you clean the MAF/IAT sensors at all? The manual says to clean the MAF insitu and not to remove it from the short section of air inlet tubing. it appears they can be damaged if mishandled. Also did you use a MAF cleaner and not carby cleaner etc.?


Can not access due to plenum - unless you know a trick that I don't in how to get in there.


A length of dowel about 10mm diameter, about 2 feet long and with a torch you can see the coloured body of the injector under the intake manifold. It can be fed though under the plenum to mechanically touch the injector. You may have to unbolt the EVAP and shift the hot water valve.
Touch your ear to the other dowel end, it will reveal all. In my 190Kw motor, I could get the dowel onto the injectors. (I have no spacers as such in the inlet manifold)

A quick query - were the injectors new or refurbished units?

Could you have cracked a spark plug/s when tensioning them down? I slide a 1/2" socket over the 3/8" extension so that the socket sits in the top of the spark plug tube and keeps the long reach plug socket centralized and minimizes the chance of damaging the spark plug with any sideways movement.


Good luck with your fault finding.

 

[TAHAIC]

After thinking about it I decided that I needed to treat this as a new problem and unrelated to work I had done previously as it was running fine for a few weeks.

First I considered that it was possible that an injector was faulty, it not the first time I have had new faulty parts. From disys input I used a piece of 1/2" copper plumbing pipe I had laying around and bent it up a little to check injectors - all clicking OK.

Next I disconnected coil packs one at a time - it was really difficult because it was running sooo bad really shitty but when the idle dropped down real low after a few minutes of running I managed to determine that No 5 had no effect when disconnected. I replaced that coil pack and all fixed!! YEY

I couldn't believe that dropping one cylinder made such a difference - Wow Holden really have **** balancing. Well I am glad its fixed and that it was so simple and that it was a coil pack I could actually get to without removing the plenum again.

Thanks for your help.

 

[routier1642]

That was my first thought (only read this today) - Bloody coil packs again.