Just over a week ago I bought my Fabia Estate and it had an LPG/Autogas conversion already done. When I filled the tank with LPG I found that the engine was only running on 3 cylinders when idle. When accelerating it would pick up. Lambda sensor picked up that the mixture was too lean and needs increasing.

Since then I've been speaking to one of my customers who is a VW technician for VW in Stafford. Told him the Fabia had the LPG conversion and he said not to use it. He said that VAG cars cannot run on LPG as it burns the valves out quickly. He said that apparently VAG engines cannot take the higher heat that LPG causes and the valve seats get damaged. The valve seats cannot be replaced either as they are actually part of the cylinder head and a new cylinder head would be needed (£1000 minimum for my engine apparently).

Is there any truth to this ????

Have also mentioned this to my dad who is a mechanic and runs his own business (engine diagnositcs) with over 36 years experience and he says that running LPG shouldn't be a problem and has never heard of any manufacturers saying that LPG conversions are harmful to their cars.

Edited 29 March, 201016 yr by rookwise

never heard of that but something is not right if it runs on 3 cylinders

p.s there are a few people that run lpg on here and have had no problems -

I wouldn't, I'm not a big fan of LPG and don't believe it has all the right properties to run in a standard engine TBH.

I ran a Petrol Volvo XC70 for a while which had an aftermarket LPG conversion fitted. The only thing I was advised to do was run 1 tank of petrol to 3 or 4 tanks of LPG as the LPG dries out the Engine where as petrol lubricated it. I got rid as it needed a gear box but it had 110k on the clock with over 100k done on LPG.

True or not it's what I was advised to a do by the man at the LPG fill up point.

Isn't the 1.4 16v fussy on fuel anyway? I'm sure the manual says for the 16v to use 98ron.

I ran a Petrol Volvo XC70 for a while which had an aftermarket LPG conversion fitted. The only thing I was advised to do was run 1 tank of petrol to 3 or 4 tanks of LPG as the LPG dries out the Engine where as petrol lubricated it. I got rid as it needed a gear box but it had 110k on the clock with over 100k done on LPG.

True or not it's what I was advised to a do by the man at the LPG fill up point.

I've also heard that one as well.

Isn't the 1.4 16v fussy on fuel anyway? I'm sure the manual says for the 16v to use 98ron.

Yeah the 1.4 16v is 98ron. Strange really as my 2002 SEAT Leon had the same engine and that could run 95ron wheras the Cupra's were only 98ron.

I've got a full day off tomorrow. Gonna hook the car back upto vagcom and see if i can sort the underfuelling out while on lpg along with some other repairs i gotta do.

If anyone else knows anymore about lpg. Please post. It's new to me so any info would be helpful.

I ran my 1.4 16v on 95 since owning it and it does appear to get progressively less responsive.

 

Ive used shell v power nitro unleaded for about 6 tanks now and although it costs more my throttle response and performance has jumped through the roof !

 

Im still unsure on lpg tho as whether to retrofit mine with it..any ideas?

Since then I've been speaking to one of my customers who is a VW technician for VW in Stafford. Told him the Fabia had the LPG conversion and he said not to use it. He said that VAG cars cannot run on LPG as it burns the valves out quickly. He said that apparently VAG engines cannot take the higher heat that LPG causes and the valve seats get damaged. The valve seats cannot be replaced either as they are actually part of the cylinder head and a new cylinder head would be needed (£1000 minimum for my engine apparently)

 

The first part is true, these engines burn exhaust valves even when running on 95 unleaded, let alone LPG.

 

The second part is nonsense, the valve seats are shrunk into the alloy head by heating the head casting and pressing in the new blank valve seat after dipping it in liquid nitrogen, the seat then has to be cut or ground to the correct profile. This is generally only necessary when an engine has suffered a catastrophic failure resulting in a damaged valve seat or if you are having larger valves installed.

 

It is entirely possible that your poor idle is being caused by burnt exhaust valves, these can be reground or replaced depending on the severity of the damage, the seats should be fine to be reground.

How much is it to replace the exhaust valves? and more to the point which valves are you referring to? within the piping or the connections between mid back and front pipes?

How much is it to replace the exhaust valves? and more to the point which valves are you referring to? within the piping or the connections between mid back and front pipes?

 

Errrr, it's a 16 valve engine Aaron, 8 of those 16 valves are exhaust valves, 2 per cylinder. Those exhaust valves, there are no others.

oh, im assuming im referring to the gaskets then lol !