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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.

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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.

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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.

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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.

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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?

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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
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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?

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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.

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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. :-)

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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

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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

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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.

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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.