hi, i've got a 3.9 v8 discovery fitted with lpg thats playing up so i've disconnected (pulled out the ignition and battery fuse to the lpg) it...

up until the lpg decided to start blowing it's own and no3/engine management fuse, the car behaved without fault, a little high on tick-over (was over 2000rpm but a new stepper motor brought it down to 1000rpm) and when started from cold/first start up won't take throttle for a minute or two...

now having disconnected the lpg (which i ran it on all the time, except for when it starts on petrol before she switched herself to lpg) the car will go into limp mode as soon as she's warm or around town/stop start with low throttle use, but if i can get her to the local bypass or give it a motorway run (i've just drove back from kent to s.wales and no probs, except for the shocking amount of petrol i had to buy/use!!!) she will run and behave normally...

my questions are, does her symptoms means she's got used to using lpg and will 'clear' herself once she get used to using petrol again, does what shes doing lean anyone towards any possible problems (i'm thinking exhaust lambda)or can anyone tell me what (cheap) diagnostic kit i can buy or is there anyone near to the pontypool area with the correct diagnostic/fault code reader would'nt mind me rocking up and plugging in for some beer tokens...

i need to get her running right, as i don't think theres much point trying to sort out the lpg untill i get a nice engine to work with, but then again she never had a bother on lpg, so perhaps i should just fix the lpg/switch her back and keep me fingers crossed!!!!

PM me with the details of the lpg system.
If I've got the leads and software we can have a look.
The lpg software takes it's readings from the ECU so it might highlight a problem with a sensor etc.

sorted now thanks....

it was the catalytic converter(s) in the 'Y' piece exhaust making the lambda/o2 sensors give a bad signal to the ecu anf throwing her into limp mode, new pice of pipe sorted it out

thanks for the advice tho

well my last post was a bit premature...

she's still doing the limp home thing, now i'm thinking fuel pressure regulator

can anyone tell me if these can be reset, stripped or in anyway fettled or should i just go buy one??

answering my own, and perhaps someone elses question, nope no resetting or fettleing of the FPR, just replacing...

finally found the culprit(s)...

and the problem????

the Throttle position sensor and Vehicle speed sensor BOTH cream crackered!!!!

after emptying the cats, changing the fuel pressure sensor, checking fuel pressure plus replacing the fuel filter, asking loads of questions on 4 forums, loosing heart, thinking bout scrapping her and generally being a right moody so n so. TPS and VSS turned out to be causing the limp mode effect ( the jury's still out as to weather my ecu has/is capable of limp mode) but now she's purring like a kitten, running and revving as you'd expect...

did 30 miles from a cold start (after letting her tick over until warm) on petrol, in varied driving conditions and styles then turned around and did the last 10 back on lpg, nothing but normal-ness!!!!

my advice to anyone in a simular position.... BUY A FAULT CODE READER ASAP!!!!

i could of saved a whole load of time and fustration by doing exactly that... the only thing i've gained is that i have a really good, intimate knowledge of my car and have changed most of her servicable parts, so they won't need looking at for (hopefully) a long time to come