My VN turned into a Volvo

[Pretender]

My VN is currently running on 5 cylinders with the thirst of a V12 and the performance of a 3 cylinder.

I need some advice.
Started it up this morning and it appeared to have lost a cylinder. It did this once last week for about 10 minutes then ran fine all week.
I have put new plugs in, Tried 3 x coils and 3 x DFI Modules, changed 2 x leads and checked all electrical connections and hoses. It still runs like a pig on either Gas or petrol but backfires severely at the slightest increase in throttle whilst on gas. Timing light appears to indicate that some plugs are not firing all the time but that could be flawed. I removed each lead in turn and it ran the same each time.

Any ideas on testing procedures to help identify the problem?
Lack of money, long story involving getting robbed, prevents me from purchasing any new parts.

Any advice would be greatly appreciated.

[pandaman]

Ok, buddski first step let's check for spark on each cylinder the foolproof way, ya may wish to pull your fuel pump relay and depressurize your fuel system so it won't start while your doing this. Pull a spark plug and crank her over while holding the plug next to the chassis. Do this for each plug in turn, if spark is missing somewhere then you can start to question why.

Two: lets be looking at fuel supply, pull the power from each injector in turn and check if the removal of that injector changes the running of the engine re-attach the bugger and move on, if you find any dud injectors, replace the mofo's with units you beg borrow or steal from the bastard next door who leaves for work at 5 in the morning at full noise. If pulling the injectors has no effect do not despair my brother! You'll need to check fuel pressure somehow, there is the accurate way, by fitting a fuel pressure guage inline between the fuel supply hose and the regulator (I think that's the best place for it) and then there's the dodgy way which will merely confirm that your fuel pump is pumping copious amounts of fuel wherever you point the disconnected hose. I do not endorse the second method, I merely observe that it will confirm fuel supply or lack thereof. Another possibility is the regulator, doubt it'd cause that much trouble though, if memory serves they're fairly robust little buggers anyway.

Three: Compression is the next concern and can show a variety of internal problems that are not immediately obvious. For this you'll most definitely need to source a compression tester and an assistant. The aforementioned begging and borrowing could probably be applied to a local fellow commodore freak to hook a brother up with some assistance. Fit the compression tester to each spark plug hole in turn and crank her over noting the highest? reading on the compression tester. Compare the results for each cylinder, if ya can't make head nor tail of em then chuck em on here and I'm sure someone will know.

Anyway, if all that wont tell you what's wrong with the vehicle, or at least put you on the right path then I'd be suspecting demonic possession. Can you tell I've had to do this before? :-) Anyways, be taking it easy and I hope this helps.

PS: Speaking of ovloV's how awesome are those new jobbies with the turbo 5 cylinder, not bad looking for one of Sven's finest and they go pretty hard too! My favourite Volvo is an old FL6 truck we used to have as a town pumper for the fire brigade, best bit was the massive centrifugal pump on the back powered by a 253, rediculously overpowered but damn it was some fun.

[pandaman]

Double post and I can't find the delete button

[Pretender]

Cheers

Runs the same on gas and petrol so it is not fuel related.

Will try the other tests after I replace all leads (brother's mate is dropping off a new set tomorrow to try). Definately feels electrical. I had not done the plug test as I was not sure what an errant spark may do to the computer.
I think my car is already possessed, or is that me?.
Perhaps I should not have had that fleeting thought of selling it a couple of weeks ago.

[pandaman]

Cheers

Runs the same on gas and petrol so it is not fuel related.

Will try the other tests after I replace all leads (brother's mate is dropping off a new set tomorrow to try). Definately feels electrical. I had not done the plug test as I was not sure what an errant spark may do to the computer.
I think my car is already possessed, or is that me?.
Perhaps I should not have had that fleeting thought of selling it a couple of weeks ago.

Lol, they can sense infidelity. Anyway, errant spark isn't a problem, (I think) spark earths through the block and hence the rest of the car anyway.

[vt1538]

The spark flows in one direction through the coil pack from one spark plug to the other. This is why an inductive timing light wont always pick up a signal.
Disconnecting one lead at a time can cause the partner cylinder to drop out as well & make it hard to isolate which cylinder is faulty. Disconnecting an injector plug I have found is the easiest way to isolate a cylinder.

[88GreenVN]

Any error codes from the ECU? Have you tried a diff ECU?
Heavy fuel usage can be temp sensor or O2 sensor related.

[Pretender]

Cheers guys, turns out I have three faulty coils. I gave away two good coils about 3months ago.
I'm in the process of tracking one down at the moment.

Can you fit a VP coil pack to the VN DFI module?

[pandaman]

Cheers guys, turns out I have three faulty coils. I gave away two good coils about 3months ago.
I'm in the process of tracking one down at the moment.

Can you fit a VP coil pack to the VN DFI module?

Don't shoot me if I'm wrong, but I'm pretty sure it's not a problem. I know bugger all about the V6.

[Pretender]

New development. Coils are all good according to my brothers mate (mechanic).
Between posts I got 12k ohms on one, 11.5K on another and 11K on the last, consistent across all three coils on each coil pack (all three read 1.1ohms between the terminals which is good).
I was lead to believe they should be between 5K - 7K between posts or they are no good. Mechanic doesn't know what the reading should be.

[vt1538]

According to Holdens manual they should be between 5k to 7k on the secondary side, between 0.3 to 1.5 on the primary.

[Pretender]

According to Holdens manual they should be between 5k to 7k on the secondary side, between 0.3 to 1.5 on the primary.

Spoke to Holden Service (Lance Gibbons Holden) Resistance should be between 10K and 14K between towers (secondary) and 0.3 and 1.5 across underside connections (primary).
Found my Gregory's Workshop manual and it confirms the 10k - 14k ohms.

So I have three good coils and three good modules and one faulty CAS.
I have had two fail on different cars but both would not run at all.

I'll keep trying to locate something I can fix with no money though.

Edit: Individual coils for the Series II and VP are 5k - 7k

[patto]

Hey Pretender...
what symptoms did you have with that faulty CAS???
Cheers

[Pretender]

Hey Pretender...
what symptoms did you have with that faulty CAS???
Cheers

It would sometimes cough when trying to accelerate from say 80km/h, I had assumed it was due to running on gas as I have it set up for better running at low speed stop start driving. It would also backfire.
It got a little worse last week so I switched to petrol but it still occured.
That was the first time I noticed it on petrol.
Later in the week I started it and it was not firing on all cylinders. I checked everything like leads, plugs etc and then started it up and it ran fine for a couple of days. Then it started doing it again but would not clear itself.
I bought new leads and new plugs and tried the two spare coil packs I have but nothing changed. I also tried a different set of leads without change.

I eventually found my manual and tested everything. All seemed good but on the second try at testing the CAS I got no signal for a quarter rotation of the
motor.

Basically running on less than six cylinders, underpowered, heavy fuel use and a different lead not firing each time you test it.
Before it got really bad it also used to stall when reversing and turning the wheel puting the motor under load.

[patto]

hmmm i have very similar symptoms.
Its just not very often they occur, might replace my CAS.
I also find that it usually only happens when the engine is hot.
Cheers

[Pretender]

All fixed now. New CAS, car started fine ran perfectly for 30 metres and then started misfiring again.
Started testing with the CAS first, couldn't fault it, then the coil pack and number six had left home. Changed the coil and now it is running fine.

A mechanic told me when my CAS went on my old Commodore that the coils sometimes fail also when the CAS dies. It didn't happen then but it did this time around.

[pandaman]

All fixed now. New CAS, car started fine ran perfectly for 30 metres and then started misfiring again.
Started testing with the CAS first, couldn't fault it, then the coil pack and number six had left home. Changed the coil and now it is running fine.

A mechanic told me when my CAS went on my old Commodore that the coils sometimes fail also when the CAS dies. It didn't happen then but it did this time around.

well that's good news.

[immortality]

i think it should now be mandatory that the CAS is checked before anything else. it's un beleivable how many time people have had different problems and it's always ended up being that danm CAS good to hear you got it going