funny noises 4.6 hse

hi everyone thanks for reading this post and hope someone can help me

i have just bourght a 4.6 hse on gas gas not working properly but i think i can get that sorted,ive got the certifacate and phoned the place that installed it and they said cus it been on nearly 3 years it will need a service and resetting,£68 so fingers crossed that will be sorted.

second problem is that when the car is running and you stand in front of the car the engine sounds great when you go round the back it sounds bad seems to be like a poping noise cumming from the exhausts.

third problem is when you start the car and leave it at idle speed very faint noise i can only call it a rumble type noise thats in park or neutral,when you put it in drive or any gear noise gets worse and you can feel viabration under your feet,when you drive off noise goes but when you stop its still there

hope someone can help as i dont want to be ripped of by a garage for all types of money and then the car still has same problems.(been there a few times)

i would like to thank you all in advance

the popping noise is prolly a misfire on one of the plugs. v8 will run on 5 cylinder, although noticably badly, given that it wont run on gas either i would assume it requires a service on the petrol side and then when the lpg fellas get that side done your problems should disappear.

i would check the transmission fluid, well check all fluids really and get a service done or diy as a first step. then see what problems are there. have a look on range rovers.net for a bit of background on usual suspects for g/box vibrations etc.

hi mate thanks for getting back
it does run on gas its just theres not a lot of power when its on gas
im starting to think its the cat rather than the gearbox well lets put it one way im hopeing it is lol

the gas system will have less power, the gas has a lower calorific value(in the region of 15% less) i would start by checking the ignition system you have to keep it tip top for gas or you get minor problems, also make sure there arnt any leaks on the air intake. that way the mixture should be correct and the ecu can keep it in check.

also make sure the leads are in good condition.

the rumble- i would get under it and see/feel if there is anything obviously loose. have a feeel around!

yes the gas has never been serviced since its been on the car so think that will be the problem,its going in to be serviced and recalibrated.

thats my next plan to get under it and see if i can see anythink

thank you very much

when yr under there make sure you chock the wheels and lock all the doors except drivers, just so no one can tamper while yr in a vulnerable position. oh and raise the suspension and you'll have bags of room!

been underneath and feelt the back of the transfer box and it seems to br comin from there.
so im taking it to a garage just to make sure,so ill keep you posted