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range rover 4.6 flat spot
Posted: Wed Sep 28, 2011 1:34 pm
by stagcar
Hi chaps,
The manta v8 build is still in progress so i am sure i will be hounding you all about this very soon
At the moment i am running around in a 97 range rover HSE 4.6
running on LPG its fine but when it on petrol it seems to hold back at about 3000 rpm it feels like a misfire. up until that it pulls well and seems to be more powerfull than on the lpg
any ideas? i would normaly have done plugs and leads but seeing as its fine on lpg i dont recon that can be the problem.
any help would be apriciated
Many thanks derek
Posted: Thu Sep 29, 2011 7:04 am
by ChrisJC
Is it a fuel injection LPG system that piggybacks on the GEMS engine management? So it's reusing the GEMS map?
Chris.
Posted: Thu Sep 29, 2011 8:37 am
by Eliot
How much fuel is in the tank? - Mine cavitates when its down to the last line, well before the light comes on.
Mine was pretty flat in the midrange as was my previos p38 as well. I've megasquirted mine now - no more flat spot or air flow meter for that matter.
Posted: Thu Sep 29, 2011 9:28 am
by stagcar
Thanks for the replys chaps
TBH i havent a clue how the lpg works it looks to me like its got its own ecu and i think its got its own lamda also.
as for the fuel at the moment its got about half a tank of fresh juice.
I have found that if you can get it past the 3000 rpm it seems to get better at about 3800 but still not good
looking on the net i am thinking airflow meter? has any one had these die before?
like i say this is normaly not a big problem becuse i use it on LPG most of the time its just a pain when it runs out and switches back to petrol specialy when your wipping it up the motorway
Thanks again
Derek
Posted: Thu Sep 29, 2011 10:13 am
by Eliot
Try removing the AFM and cleaning it with isopropol or contact cleaner. Not a 100% fix but it should improve things if it is flaky(dirty).
Posted: Thu Sep 29, 2011 11:53 am
by ChrisJC
You could try getting any faults read out of the ECU.
Chris.
Posted: Thu Sep 29, 2011 1:28 pm
by Eliot
Unless its really broken, it probably wont show anything.
I chased my arse on my hesitating P38 - turned out to be the fuel cavitating in the tank. Although it was the diagnostics that helped me find it, because i could turn the fuel pump on manually and i happened to hear it. I was actually trying to test the fuel pressure at the time - so i was close!