Funny you should mention the valves... After getting the car back from the LPG specialist (it passed with flying colours), I went to book it into the local auto-electricians. They were very helpful by advising me of two things. First, the miss fire is unlikely to be electrical if the coils and plugs have been changed as this is all that tends to go wrong with these engines.

Secondly, the higher operating temperatures of the LPG probably means that the valves are shot. They appeared to know what they are talking about.

Hence, my grease monkey is being let loose on the car next week to get a compression test done. We are slowly getting there!

Funny you should mention the valves... After getting the car back from the LPG specialist (it passed with flying colours), I went to book it into the local auto-electricians. They were very helpful by advising me of two things. First, the miss fire is unlikely to be electrical if the coils and plugs have been changed as this is all that tends to go wrong with these engines.

Secondly, the higher operating temperatures of the LPG probably means that the valves are shot. They appeared to know what they are talking about.

Hence, my grease monkey is being let loose on the car next week to get a compression test done. We are slowly getting there!

When all else has been discarded, whatever remains, no matter how unlikely it seems, must be correct.

Just back from my grease monkey who has carried out the compression test. Cylinders 2,3 & 4 hit between 110 & 125psi. Sweet FA on #1 cylinder though. A quick check that the piston was sound confirmed that the fault is indeed with the valves.

Therefore, we have decided on a complete top end rebuild. I have ordered new valves, inlet and outlet, a new cylinder head gasket set, a new timing belt and an oil and filter change for good order. That way we should fix it up good and proper.

Whole thing should be complete in a couple of weeks. I'll let you know how we get on.

Glad to see the process of elimination has hopefully found the likely cause

Cheers for the update. This is why a "help" type question sometimes results in a list of supplimentaries.

Maybe nice to know that the engine light may come on again after driving

for some weeks (or days), due to the fact that lpg not always goes well with the ECU.

My vRS (2001) runs 30k on lpg now, without problems, but with the engine light once in a while.

I keep resetting it (tip of the lpg company).

Hope you solf the problem with the rebuild.

Good luck!

Thought I would give a quick update on progress. After the car sitting at the garage for 4 long weeks waiting on a slot, work has now commenced. The head is off and as suspeted two exhause valves on cylinder 1 were shot.

Unfortunately, three of the valve seats also need replacing, so the head is now off to the local Skoda dealer to have these fitted.

The head shold be back sometime later next week, so it looks like the car will finally be back on the road by the beginning of September. Just in time for the tax to run out & for the MOT in October.

Cost wise, we are still within budget. In any event, I plan on keeping this car for a long time as it will fulfil all my requirements: estate car for the dog and large loads, sporty handling with a suspension upgrage soon; more bhp once I am sure the set up is working; 4wd for the winter and muddy fields and best of all lovely lpg at 39.9ppl.

Ok, another update....5 weeks later and the head has just returned this week!!! It is just being rebuilt just now, but there is a problem in setting up the valve and cam timing which we are working through.

Great thread, which LPG kit is the car running.

Thanks, car is running a Landi kit. Unfortunately, the tube who converted it suffered from an ****/elbow identity crisis, since all these problems would have been easily avoided if he had done it properly. But, I am confident that the head work and the lpg safety check will prove worthwhile in the long run.

We are still experiencing a real problem with the rebuild though. Although everything is correctly alligned between the crank and the cylinder head, the engine only hand turns 3/4 of the way. A chat with Skoda suggests a problem with No 4 cylinder, maybe the piston. All of which is a bit of a mystery since that cylinder was the best one on the compression test and all the damage was at the other end.

Unfortunately, this means taking the entire head off again, and check that No 4 had turns freely. If it doesn't, we have a new problem. If it does, then it will be a matter of rebuilding again and checking all the tollerances and torque settings twice. Happy Days!

Thought I would give a quick update on progress. After the car sitting at the garage for 4 long weeks waiting on a slot, work has now commenced. The head is off and as suspeted two exhause valves on cylinder 1 were shot.

Unfortunately, three of the valve seats also need replacing, so the head is now off to the local Skoda dealer to have these fitted.

The head shold be back sometime later next week, so it looks like the car will finally be back on the road by the beginning of September. Just in time for the tax to run out & for the MOT in October.

Cost wise, we are still within budget. In any event, I plan on keeping this car for a long time as it will fulfil all my requirements: estate car for the dog and large loads, sporty handling with a suspension upgrage soon; more bhp once I am sure the set up is working; 4wd for the winter and muddy fields and best of all lovely lpg at 39.9ppl.

If you are upgrading the suspension due to the existing being "tired" I have a complete 4x4 suspension from a 2002 1.8T that covered 8000 miles before being replaced with a lowered set up for fast road use. It was cleaned & oiled before storing, Im open to offers

Car is now rebuilt, but is running as rough as hell. Everything has been checked and rechecked and we cannot find anything mechanically wrong with it.

One of the few possibilities, and it is a long shot, is that the unleaded petrol that has been in the tank for well over 4 months has gone off. Sounds mad, but it actually happened to a mate of mine. He tried to get his motorbike running again after a winter lay off this year and the bike was running all over the place before it cut out completely. His mechanic diagnosed that the unleaded petrol had degraded to the point where it was worse than 2 star. The tank was drained, he put in some super unleaded and after a couple of coughs and splutters, off it went and never gave another problem.

Apparently, it’s quite a common problem with petrol mowers. I also found a couple of web pages which also commented that the petrol has a limited shelf life and does degrade completely within 12 months.

One particular issue with my car which could be exacerbating the problem is that since it runs on LPG, which is believe it or not 110 octane fuel, the engine timing has been set for a compromise between that and 95 octane unleaded. So, the question is, would this cause a greater problem in a LPG car?

Unfortunately, there’s no LPG in the car as I ran it down before I we started work on it. So the only options now are to either get the car to the LPG station, put some in it, try and get it warmed up to switch it over to gas.. Or, we drain the tank and put in a can of super unleaded and try the same thing. If it settles down, the petrol is fecked, if not, the car’s fecked.

I also plan on checking the engine codes with the VAG com to see what comes up.

Another update soon.

Quick update.

Have run diagnostics....no codes!

Am now moving onto drain the existing fuel.

Ok, we've tried new petrol and it's exactly the same. Now what? Anyone got any ideas?

When you say the car is running as rough as hell can you describe the problem, is it simply rough tickover, does it smooth out when the revs rise ??

Mechanic has not been too specific here, but from what I can gather, it's rough all over the rev range.

I think I know what you are getting at though - the solenoid on the VVT; where if it has gone wonky, it'll still rev correctly at some point on the rev range. I have asked him to double check this.

I ahve also invested in an er-win vw workshop manual for the AUQ/AUM/ARX engine. Apparently, all these three engines are the same up top, mine, the ARX, is only labled so as a 4wd car.

So, we will see what happens with these two options.

Ok, can now confirm that engine was rebuild and started. It ran perfectly on choke and idled happily for a good 10 minutes on petrol. Engine was then revved and gradually lost power until it cut out.

When cranking the engine, fuel is being pumped, but it won't start at all. Spark etc all ok.

If it's pumping fuel, and sparking, but not starting, then either the ignition timing is way out, or the inectors aren't injecting I think.

Yeh, had that idea, but then struck on something slightly more likely that looks like it ticks all the boxes above.

The car is supposed to start on petrol and then switch to gas when a combination of engine temperature and revs allow. Basically, when the engine is warm enough and the car is reved over 1600 rpm, the gas should cut in. As per above.

But there was no gas in it, as stated before.

My guess is that it is now trying to start on gas because that's a default setting which allows it to do that if there a problem logged. With the car being off the road for nearly 4 months now, it could be likely that the system has developed such a fault.

In either event, I thinkt the best thing to do now is get some gas in it. Easier said than done since the nearest supplier is a 25m round trip - on a tow! You can't exactly fill a tin with gas!

Then we should know. If it starts on gas, then at least I can get it to a gas specialist. If it doesn't the injectors could be the problem right enoigh.

Ok, final post here.

Spent 2 hours last night on the car. Have managed to rule out the LPG which has been disconnected. LPG is not at fault.

Basically, car is trying to start, but only ruins for 5-10 seconds before cutting out. Initially thought it was being starved of fuel, but after checking plugs they were coated in petrol, so we thought it may have been flooded. No problem with the injectors either then.

We put in a new set of plugs, but exactly the same thing happened.So we now have one sure problem, apparently confirmed by vag com.

I think I have taken this thread down so many blind alleys, the best thing to do now is to close this one down and start up another with the known fault. Although I will put in a link back to this one.

Many thanks to everyone for your help. I'm sure we will get this car going eventually.

P

Hi I have the same problem on my octavia 1.8t 4x4 lpg and have done similar to you could you let me know the end results

many thanks

[email protected]