LPG issue with coil pack

[carcathan]

Query for anyone's feedback - but particularly hoping classicswede can comment (Hi Dai, can't send you a private pm - the LPG has been running a treat for 15,000 miles, this is the first problem which seems to relate to the coil packs and a recent ETM replacement).

Has anyone experienced a problem with the feed to the coil packs only on LPG?

Having had a code for faulty coil pack on cylinder 4 that was affecting both petrol and lpg, i changed the coil pack for what appeared to be a good used spare. The car (2001 C70 2.4LPT on LPG) runs well on petrol now but still fails to fire on cylinder 4 on lpg.

Today i picked up some new coils. Having mixed and matched these across the cylinders to see if i got any change - i still can't get cylinder 4 to run on LPG. If i disconnect the plug from the coil pack on 4 it makes no difference to the running on LPG so it is definitely failing. Also if i unplug the LPG injector for 4 it makes no difference to running.

I cleared the codes and it hasn't picked up the misfire again until i unplug 4 in which case i then get a general fault with primary or secondary coil circuit.

My query is would the LPG system control the feed to the coil pack?

The car had a new ETM a couple of moths ago and this problem has persisted since then, but amongst the other ETM symptoms i'm not sure if it was a problem before that. Would the new ETM have thrown something in the LPG ECU?

As this problem started with both petrol and lpg, i have raised a general query in respect of the wiring to the coil feed in the C70 technical section.

Thanks,
Richard

[capt jack]

Bear in mind that LPG is less forgiving of any electrical deficiencies than is petrol. I believe it's true that many apparent 'LPG-only' running issues that don't seem to appear when running on petrol are often down to ignition problems.

I know for example that my converted V70 used to develop a misfire on LPG that went away on petrol. This had me puzzled until I was told to replace the spark plugs every 10k miles.

I also had similar LPG misfire problems when the HT leads reached 100,000 miles old, and when the rotor and dissy cap got tired. Even though all these components looked OK and the car ran fine on petrol, each time, new components sorted the problem.

The other 'weak point' as far as my experience has been in around 170,000 miles of LPG driving, are the LPG injectors, or more properly solenoids. A squirt of injector cleaner has been useful once or twice.

Finally, and very importantly, when was the LPG filter last changed? LPG is a surprisingly 'dirty' fuel, and certainly in my experience, the filter needs changing every 10 to 12 thousand miles.

I appreciate that my experience of a conversion rather than a factory-fit, but my guess is that the basics are just the same.

Cheers

Jack

[ctautos]

that is well worth knowing thank"s jack

[carcathan]

Thanks Jack.
So far i have changed all the plugs, as mentioned changed all the coil packs (though not all new, the old ones were not misfiring on other cylinders), just changed the lpg filter (engine bay one) today.

I did look at the injectors, especially as i have one unused as its an aftermarket conversion KME kit with the 6th injector unused. How did you use your injector cleaner?

As you mention i've come to realise the sensitivity of the LPG on the ignition side, but can't help feeling this is not the coil pack itself now. It's either the LPG ECU switching off the feed to the 4th cylinder coil pack (but i'm not sure if it works that way) or the lpg injector failing. Or neither of these but something i don't understand!!! An initial response in the technical section suggests that the coil feed wires may have chaffed/shorted - but then i'd assume this would affect the petrol spark too.

I've seen an ebay kit to connect the KME kit up to a laptop and wonder if that is the best step - assuming i'd understand what it was telling me.

Thanks Jack, i knew that you have some ideas. Hoping that classicswede will catch this shortly too.

[classicswede]

Hi Richard,

the only connection the LPG has to the coil pack is a RPM pick up from 1 coil. I normaly connect to either cyl 1 or 5 but can be any. You will se the brown wire tagged on to one of the centre wires.

If the plugs have not been changed since conversion it would be worth replacing them before anything else.

If you need to call me my number is 07824887160

[carcathan]

Hi Dai, thanks for the response. What is the best tie of day to call you?

Plugs have been changed (every 8k) and just changed the filter. Have to say it has been fab up till now.
I wondered if the volvo dealer could have screwed up the LPG when changing the ETM....

Hope to catch you by phone.

[capt jack]

Hi Richard

Using the injector cleaner was easy. I ran the engine until it was warm. I wanted to be sure that it would run on LPG as soon as I re-started it.

Then I just took off the pipe from the filter to the solenoids at the filter end, and squirted a few ml of injector cleaner down using an old syringe. Then I connected it all back up, started the engine and away she went!

Again, mine's a conversion, so everything is obvious and easy to get at. In the picture you can clearly see where the fuel rail, solenoids and gas regulator have been installed.

Cheers

Jack

[classicswede]

Usualy any time - if no answer I will call back