V6 Backfire

[Guest djdoylie]

This is a new thread following on my 'lumpy running v6' thread.

I started a new one as I have gone back to basics to try to get things working right.

The car is a mk1 which was running ok for nearly a year.

The car has an lpg conversion (gas ring type), the airbox has been removed and a large KN type filter fitted just before the air sensor.

I've been running on 'just petrol' for a couple of weeks now - having disconnected the battery to reset the engine management.

It seems to run fine except that whenever I start from cold I get little 'backfires' - usually two or three before I get to the dual carriageway (when, I suppose, the car warms up and the problem is no more).

They are not massive backfires, but they obviously should not be there - and (obviously again) I should get this sorted before moving on to the lpg.

The 'backfires' seem to be at the 'front' of the drivers position (rather than behind, from the exhaust). They also seem to come when the auto changes gear.

Note: I still have the 'big KN type' air filter fitted.

The 'plastic 'T piece' vacuum thingy (see earlier in 'lumpy running' thread) is still unconnected to anything on the 'leg end'.

By the way is the airbox system for the v6 the same as used on the 2.0 petrol?

(I am thinking of trying to get a used one and putting that on to see if it helps with this problem.

Any ideas guys?

PS. Is there anyone near the beds / cambs border that has a VAG COM (and knows how to use it)?

[johnb80]

For what it's worth KN type filters and lpg conversions of the type you have are not a good combination. The KN is too free flowing and doesn't cause enough vacuum to get the gas sucked into the engine properly as a result the mixture will be all over the place when running on LPG. I don't have personal experience of Galaxies on LPG but all of the above was very true with Range Rover V8's on LPG.

 

Regards - JB

[Guest dbpreston]

I also have Galaxy V6 - early 99 manual model, and I recall that the plastic T-piece which I think is some sort of vacuum breather pipe broke c.3 years ago.

The third T-piece leg is connected on mine.

 

Ran with it taped up for while and eventually got a replacement T from VW garage and replaced the short leg of hose with a longer piece. I think a symptom at the time was a slight reduction in engine power, but never had any backfire issues.

 

It's been ok since, although I'm back on the forum to explore a more serious engine power problem ;( - I think I have another thread coming.

 

I'll get a chance to take a pic of this in a couple of days if it's still in question.

Regards - David