You can try that but if it is intermittent the most likely thing is a sticky idle air valve. Take that off and give it a good blast with carb cleaner.

I'll second the IACV. The spool should move freely when you rotate the unit on the axis of the spool. If it doesn't, a damn good squirt until all the carbon gunk is off will probably do the trick.

Before i started messing about with any of the electrics and lpg tuning, i swapped the MAF and IAC valve from the other car. Symptoms still persist itermittently.

For the sake of thoroughness, i will take it off and inspect/clean it.

I reckon there's an inbalance somewhere. Can feel the vibration. A little like a helicopter. Dunno how to describe it properly. I still think it's down on power. Slower acceleration.

Sprayed carb cleaner but idle didn't change. Throttle body butterfly plate was a bit black so gave that a clean. Noticed that it wasn't closing all the way every time. seems to have been the cruise control cable. loosened that off a couple of turns and it shuts properly now. I'll see what it's like on a drive.

Seems to have worked a treat. I still feel tho, that there may be something not quite right. I might just be being picky, but coming through the village doing about 30mph, took foot off accelerator and the car kept going smoothly as though i still had my foot on (wafting along nicely). It was gradually slowing but not as quick as i imagine it should.

As i say, i cleaned the throttle body with carb cleaner. I didn't take it off as i don't have a new gasket. I assume that there's a hole somewhere in the throttle body (that i can't see without taking it off) where the IAC valve draws it's air from? Might that be gunked up also?

You said you backed off the CC cable a couple of turns. Did you adjust it as per spec? If you don't have that gap the CC will continue to hold the throttle valve slightly open

yeah mate. with the air intake hose off, i could see that the butterfly wasn't always closing all the way. It was the cruise control cable. So backed that off and the butterfly is shutting perfect everytime.

Like i say tho, i still feel that the car is being helped along sometimes with no accelerator. That's why i ask about the IAC valve. With your foot off the accelerator, does the IAC take over? If so, i reckon that might be to blame. The IACV is from the other range rover i have. I swapped it when i began this fault finding process a couple of weeks ago, but it made no difference. So im confident that the valve itself is good. I just think the airway going to it might be the cause.

What do you think?

I had a crack on the fitting where the IACV hose goes into the upstream side of the inlet manifold which caused a rough idle. Repaired the crack. Cleaned the IACV but wasn't happy that it was moving freely so stuck on a spare. Idle was still inconsistent so reset Adaptives and idle settled back to what it should be. If you don't have the means to reset Adaptives you may have to wait a while until things settle down to accommodate the changes you made when you changed the throttle butterfly position.

had it all setup last week by Simon as lpg was running a bit rough. Nothing was set in lpg ecu so he did it all. Was running great. Then i got fault p1171 a few times. That's not shown up for a few days now but i've still intermittently had this wobbly roughness when foot comes off accelerator and braking. That's why i've had a look in throttle body today. I still think there might be more cleaning to do so perhaps i'll get hold of a gasket, take the throttle body off and do it properly. It has made a huge difference by cleaning it and resetting butterfly.

If i run it on petrol only, adaptives will reset wont they? But, the lpg settings will have to be done again??

Thanks for the reply. :-)

The trims will adjust themselves over time. The adaptive reset just gets things back to a base level straight away.
As the LPG settings are directly mapped to petrol injector timing they will reflect the trim changes, so shouldn't need much (if any) tweaking

I also got the impression throttle was sometimes being held open a little by adjustment of throttle/kickdown cables, seemed to prevent idle from settling below rpm1000 a few times.

Will have to see what's going on again with fuelling... injectors all seemed to be performing consistently at the time but a bank trim was necessary to balance petrol trims.

Simon

Drove not bad today. It's not unbearable by any means. I just know that there's something not quite right. I'll run it for a while and see how it develops.

Got codes

P1171 (still) which i believe is both banks running lean

and i've got

P1174 which i dunno cause i can't get a straight answer from googling. Some say MAF, Some say it's caused by vacuum leaks

This was running on petrol only.

I checked for vacuum leaks the other day with some carb cleaner but didn't seem to find anything.