Zafira Koltec issues

[neilw]

HI, apologies in advance for the long story. I'm not sure if anyone can help... but:

My wife's Zafira is the fifth(!) Vauxhall factory-fit LPG car in our family. It's got 163k on the clock and in common with the earlier vectras its started to become reluctant to switch over to LGP, especially when cold, and to switch back at random moments.

I have discovered how tight the Zafira bonnet is compared to a Vectra or even an Astra!

I have cleaned out the vapouriser and fitted a seal kit. This solved the problem on two Vectras, but things don't seem to be quite right with the Zafira.

The low pressure valve was sticky enough not to fall under its own weight, but I'm sure I fixed this. After a false start (I bent one of the pins on the solenoid valve connector) it worked OK at first, but then became really flaky, cutting out all the time at about 60-70 mph. A check on the gas pressure at the rail showed only 0.1 bar, but rising to 1 bar before/after running on LPG. I checked the filter and that's clear, and I was going to remove and clean the solenoid valve, except the problem appeared to clear itself.

My wife is very unhappy with how the car is running. I haven't been able to test it from really cold (i.e. first thing in the morning).

She drove it this morning and is sure it lacks power in the mid range, & the engine is noisier - I can't judge this as I rarely drive it. She also found that it still took a long time to run properly on gas in the morning and was running very unevenly and kept switching back to petrol. I just did about 25 miles this afternoon and couldn't detect any issues, but she says it lacks power.

One thing I do agree with her on is that for some reason, if you stall on gas or it doesn't change over properly when idling it won't fire at when the gas switch is on, switch the gas off and it starts on petrol, switch gas on and if warm switches to gas OK.


Is it possible the solenoid valve may be sticking/partially blocked? I'm guessing this could be intermittent and might go away completely. If it doesn't how do I disassemble and clean the valve?

Why isn't it switching back to petrol when the car stalls on gas? Is it possible I've got a bad connection somewhere?

Finally, might the flat spot/rougher running should clear itself as the ECU remaps itself? Is 3-4 days the right amount of time to allow for this?

TIA for any pointers.

Neil

[rossko]

Is it possible the solenoid valve may be sticking

Yup, thats common enough and may appear temperature sensitive.

how do I disassemble and clean the valve?

Depressurise supply pipe, remove coil bobbin, unscrew the tube inside that using the hex at the base, which containes the plunger.

Why isn't it switching back to petrol when the car stalls on gas?

because it happens too quickly, it takes time to detect and act on other problems.

Is it possible I've got a bad connection somewhere?

Yup, previously bent pin at the solenoid has to be on your suspect list

Finally, might the flat spot/rougher running should clear itself as the ECU remaps itself?

It's really unlikely. Fix the gross problem and see what's left afterwards. Don't overlook the usual suspects like plugs and coils.

[baz57]

re vapouriser if you have cleaned it out how have you reset the pressure ?? you need 1.5 bar [21psi] outlet pressure otherwise your pressure sensor will detect low pressure and switch to gas another thing is with your wifes model the injectors are upside down and prone to sticking accumalating @!## on them
as for the solonoid you can get a replacement for about £27 if you need one these systems have a recomended life of about 250,000 miles so expect to replace parts if you have a high mileage car mines done 376.000 !!!
hope you get it sorted
Baz

[neilw]

Thanks for the pointers. If it keeps playing up for the first half hour or so, I will recheck the gas pressure tomorrow evening, and if it isn't sorted by the weekend I'll fetch it out (again...) and strip the solenoid valve as described.

I thought the sensor on the vapouriser was for temperature - I assume now its for pressure and is what tells the system to switch over/back again?

Thanks again for helpful suggestions.

Neil

[baz57]

hello again there are 2 electrical connections on the vaporiser 1 is for the solonoid 2 the temp switch. if the temp switch is faulty or you have an air lock in your heater system gas switch over can fail or be erratic hope this helps

[neilw]

Hello again,

I've worked through the options and it seems to be the solenoid valve. It takes a great deal of pressure to push the plunger up, and once it's in it will only come out if I warm it up. It also becomes freer, but not as free as I would expect.

I now see the plunger's a sealed unit. Is there a way of cleaning it? I've tried getting brake/clutch cleaner in and now it's soaking in meths. The first option seemed to get some cloudy black deposit out of it, but no noticeable freeing up.

If it's a case of replacement can anyone advise a good source?

Thanke again.

Neil

[neilw]

I finished typing this, looked for valves on the 'net and then went and had a look at the valve in hope, not expectation. In the meths the plunger had come fee and pulled straight out of the barrel. The deposit looked like soot.

I polished it up inside and out with a cotton bud, put everything together and fingers crossed - everything now OK. It changed onto gas about a minute after starting from cold and then changes almost instantly - and no hiccups and the power is back

Anyone reading this - check the solenoid valve before you clean the vapouriser - you may need to do both or just one!

Also, meths is a good solvent for cleaning gas-gunk, it seems.

Thanks for the pointers that helped me sort this one.

Neil

[neilw]

My wife reports that the car still isn't perfect. From cold it changes to LPG after about a minute (it was -1.5 this morning).

Over the first eight miles, it was still periodically clicking back to petrol, but then fine for the rest of the day.

The pressure is now 0.95 bar with the vacuum pipe connected and about 0.2 bar with it connected (before it was 0.15 regardless of whether the vacuum pipe was connected or not).

She thinks it seems to click over when the car hits a bump. Is it possible that one of the knock sensors or similar is over sensitive and interprets a bump or judder as the LPG failing?

Thanks

Neil

[rossko]

The pressure is now 0.95 bar with the vacuum pipe connected and about 0.2 bar with it connected (before it was 0.15 regardless of whether the vacuum pipe was connected or not).

Where are you measuring that? I'd expect ~ 0.95 bar at vaporiser output when idling with vacuum pipe off.