H-M3 Posted January 5, 2008 Share Posted January 5, 2008 Hi peeps and late Happy new Year. I need your help please I own a 2001 4.6 vouge with LPG (romano) system installed about year and half ago. Basically car has started to misfire. It also is not idling as it use to. I serviced the car at stealers about 2000 miles ago so all new plugs (ngk platnium) filter etc. I thought it might be just when running on lpg but it is still same on petrol too. I had a friend look at it at his garage he reckons its something to do with a air leak. I am also looking at the service records it shows that the HT leads were replaced around Nov 2004. The lpg instalers recommend to change the ht leads??? I dont know where to start its not very aggresive missfire but car hesitates on accelaration and you can hear the thump in the exhaust. any ideas guys? Sorry for the very long thread. NB: Can anyone reomend any garage in london please. Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted January 5, 2008 Share Posted January 5, 2008 If your mate thinks it's an air leak then I'd have a hunt around and see if you can find an air leak - a can of aerosol carb cleaner sprayed onto strategic points (EG hose joints) will cause a brief cough if it's leaking into the inlet manifold. Just don't spray it about the place too liberally as it's rather flammable Are the NGK Platinum plugs fancy type or just expensive normal ones, 'cos V8's don't like fancy plugs - normal NGK BP6RES seem to give best results. With LPG it's important to have a strong spark so good HT leads (as in genuine parts not fancy pants brightly coloured tat) will help. Quote Link to comment Share on other sites More sharing options...
H-M3 Posted January 6, 2008 Author Share Posted January 6, 2008 If your mate thinks it's an air leak then I'd have a hunt around and see if you can find an air leak - a can of aerosol carb cleaner sprayed onto strategic points (EG hose joints) will cause a brief cough if it's leaking into the inlet manifold. Just don't spray it about the place too liberally as it's rather flammable Are the NGK Platinum plugs fancy type or just expensive normal ones, 'cos V8's don't like fancy plugs - normal NGK BP6RES seem to give best results. With LPG it's important to have a strong spark so good HT leads (as in genuine parts not fancy pants brightly coloured tat) will help. Thanks for your quick response, we have tried the spray thing with wd40 but no luck. Also the spark plugs were recomeneded by ngk tec department they are NGK PFR6N-11, any good? gap have been adjusted Also would you think its worth while replacing the ht leads as they are 3 years old. they were OE from main dealer? I saw some on ebay heavy duty 7mm ones and also at paddockspares sell them? I dont know what they are like??? many thanks Quote Link to comment Share on other sites More sharing options...
DEANO3528 Posted January 6, 2008 Share Posted January 6, 2008 My personal preference for leads is Bosch, although I believe Magnecor come recommended for LPG installations. PFR6N-11 is the recommended plug for that engine from 99> Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted January 6, 2008 Share Posted January 6, 2008 OE (Bosch, Lucas) leads are OK, Magnecor are excellent, a lot of the others are variable and many are just brightly coloured bling rubbish so I'd stick with the first three. Outside the usual ignition stuff, yours should be distributorless (coil pack fired by ECU) so we could be hunting for a dodgy sensor somewhere. In fact if your LPG kit takes its signal from the original ECU it could even be a fuelling issue although being the same on LPG and petrol rules out the actual fuel system. Quote Link to comment Share on other sites More sharing options...
paintman Posted January 6, 2008 Share Posted January 6, 2008 Notwithstanding that they are nearly new, it could also be a faulty plug. NGK are recommended for LPG & are usually excellent. Having said that, the only misfire issues I have had with mine have been.....a faulty plug. Quote Link to comment Share on other sites More sharing options...
Hybrid_From_Hell Posted January 6, 2008 Share Posted January 6, 2008 Have a lookie at your coil pack - the one that is 8 together fails regularly 2x twins are far bettter and are a later upgrade / replacment The Plat Plugs are there more for long service intervals nothing more Check for air leaks, plug gaps, plug leads fuully connected at both ends, and not chaffing on something, buy and extra plug and play swapseees, and essentially GOOD Earths on the loom to earth connections ....then your into dignostics really Nige Quote Link to comment Share on other sites More sharing options...
H-M3 Posted January 7, 2008 Author Share Posted January 7, 2008 Thanks guys for all your help, is it possible for the ht leads to become faulty after 3 years? also can I use another spark plug from the ones I have in there and also How do I access the coil? where is it located? Thanks I think I am just going to book it into network 4x4 garage???? any comment on them? Thanks Quote Link to comment Share on other sites More sharing options...
paintman Posted January 7, 2008 Share Posted January 7, 2008 Yes, leads can go faulty at any time. Follow the lead from a plug. Coil pack at the other end. NGK plugs are recommended for LPG cars. You could always try a new plug, swapping it one at a time with those fitted to see if it makes a difference if you feel so inclined! Don't be tempted to try the multi-contact plugs if the oe spec for the vehicle is single contact - that info from NGK. Have a look through the info given at http://www.go-lpg.co.uk/hints.html Quote Link to comment Share on other sites More sharing options...
Rickjw Posted May 14, 2008 Share Posted May 14, 2008 Hello there, I have been reading this thread and I have the same problem but its worse. The rangie is a 95 4.6 with lpg it will run for a short while and then stops miss firing and has problems re starting. Again the same on petrol and lpg - slightly better on lpg. The question I have is the spark plugs - one of the posts say use normal ngk plugs but no one said anything about not using the more expensive platinum tip ones. Also if H-M3 is reading this. what cured the problem ?? Quote Link to comment Share on other sites More sharing options...
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