V6 Commodore Guru's

[STUMPY]

Ok, so i was getting the hilux ready for the watagans night run and it started to sound as though it was running on 4 cylinders and underpowered. No code was coming up on the diagnostic lamp.

Once the engine was cooled and then restarted it would run fine until the engine reached operational temps.

We were getting a good arc off the coil pack and the fact that this problem wasn't happening on cold start up ruled out ignition.

After talking to some of the guys on the trip the thought was that i could be the crank angle sensor. This morning i drove the truck until the problem came back and turned off the engine and poured water over the sensor and drove it again. It seemed to help the problem, it was still running rough but better.


OK techies, What do you think the problem is???

Cheers Joel

[RUFF]

Sounds like Crank Angle Sensor to me. VL Commodores have the same symptoms when the CAS goes out.

[CRUSHU]

usually the v6 crank sensor will cut out completely, until it cools, so you will be driving along, then the car will cut out. you pull over, wait a few minutes, then it starts again, good as new.

[mkpatrol]

usually the v6 crank sensor will cut out completely, until it cools, so you will be driving along, then the car will cut out. you pull over, wait a few minutes, then it starts again, good as new.

This is spot on.

Ceck, spark plugs & leads first as they can be faulty when hot. These things are after the coil & play up all the time on these engines. Make sure the heat sheilds are kept on the ends of the plug leads as they are critical for protection from the heat and arcing of the spark to the exhaust manifold.


What is probably wrong is the DFI module under the coils themselves, they can throw a good spark but at the wrong time.

What model V6 is it & what have you checked/replaced?

[STUMPY]

usually the v6 crank sensor will cut out completely, until it cools, so you will be driving along, then the car will cut out. you pull over, wait a few minutes, then it starts again, good as new.

This is spot on.

Ceck, spark plugs & leads first as they can be faulty when hot. These things are after the coil & play up all the time on these engines. Make sure the heat sheilds are kept on the ends of the plug leads as they are critical for protection from the heat and arcing of the spark to the exhaust manifold.


What is probably wrong is the DFI module under the coils themselves, they can throw a good spark but at the wrong time.

What model V6 is it & what have you checked/replaced?

It's a VN series 1 so the coil pack is a one piece pack. Henry from the board suggested that it maybe the DFI module awell.

[STUMPY]

usually the v6 crank sensor will cut out completely, until it cools, so you will be driving along, then the car will cut out. you pull over, wait a few minutes, then it starts again, good as new.

This is spot on.

Ceck, spark plugs & leads first as they can be faulty when hot. These things are after the coil & play up all the time on these engines. Make sure the heat sheilds are kept on the ends of the plug leads as they are critical for protection from the heat and arcing of the spark to the exhaust manifold.


What is probably wrong is the DFI module under the coils themselves, they can throw a good spark but at the wrong time.

What model V6 is it & what have you checked/replaced?

It's a VN series 1 so the coil pack is a one piece pack. Henry from the board suggested that it maybe the DFI module awell. Haven't replaced anything yet. thought i'd get some ideas before throwing money around.

[mkpatrol]

Yep & those coil packs were prone to crossfiring as they would crack & do all sorts of things.

Usually when one section for the pack craps it dropps two cylinders.

Quick diagnosis check is to remove the injectors while it is running (idling with the miss) & see if there is a difference in the engine revs. If one or two cylinders dont change the revs when an injector is pulled then I would say a plug, lead, coil or DFI module is crook. They are pretty simple to diagnose, the old VN engine was the closest thing to points & plugs you can get in a fuel injection system.

[STUMPY]

Yep & those coil packs were prone to crossfiring as they would crack & do all sorts of things.

Usually when one section for the pack craps it dropps two cylinders.

Quick diagnosis check is to remove the injectors while it is running (idling with the miss) & see if there is a difference in the engine revs. If one or two cylinders dont change the revs when an injector is pulled then I would say a plug, lead, coil or DFI module is crook. They are pretty simple to diagnose, the old VN engine was the closest thing to points & plugs you can get in a fuel injection system.

Thank you.

Something that i may have miss lead you in my opening statement was the arc from the pack wasn't as strong for one of the packs as the other. i'll look at it tonight. thanks for all your help.

Cheers Joel

[mkpatrol]

I have been in Craptoria, how did you go?

[Roctoy]

crank angle sensor dude, change it before anything else, it's the cheapest.

Chris

[STUMPY]

Well i haven't done a great deal on it yet.

Just got back from repco which didn't really have anything in stock. i ordered a coil pack and the crank angle sensor which i get tomorrow.

I was going to get DFI sensor but nearly had a heart attack at the price. $414 they wanted. It's worth more than my car. I'll start off with the crank angle sensor and go from there.

Cheers joel

[bigpat]

Seen this prob when working on Formula 4000 (Formula Holden) engines.

Thse are the only things they need to run:

Crank Angle sensor
DFI / Coil Pack
MAP sensor
Engine Temp Sensor
TPS ( Though they will run without one)

As mentioned above, I think the DFI / Coil Pack would be crook. Simply use a VN Series II, or VP one. Make sure it isn't cross firing across the leads straoight out from the coil pack itself. Even with well insulated Magnecor leads, the race engines would do it. We used to put 3 layers of heat shrink over the boots and zip tie them to a simple bracket to hold them apart, to fix it. I'm 90% sure this is you're problem. They aren't sequential injection, from memory they fire 2 at a time...... I may be wrong tho.

Make sure you don't buy a VR Crank sensor as they have a different mounting bracket. Be doubly sure that the chopper wheel does'nt clip the sensor as well.

You can check for a dud injector by unclipping one at a time. If it does'nt hestate /run rough, it could be that, BUT swap 2 injector plugs over on 2 injectors, to make sure it not the plug itself. Or check the terminal with a test light.l

[STUMPY]

I replaced the CAS tonight with no success. tomorrow i'll try new plugs lead and coil pack.

Cheers joel