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PostPosted: Sat Feb 09, 2013 9:35 pm 
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Hi all I'm new to this forum and just wondering whether anyone has experience in this area? I've got a VZ LS1 Commodore with Emer SGI. It's had a MAF tune with recalibration of timing and fuel maps, extractors and twin exhausts and about to get a OTRCAI. Currently runs around 225rwkw on petrol. The question I have is can the Emer system be further tweaked independently as I understand it has its own ECU that "piggy backs" on the vehicles base tune?


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PostPosted: Sat Feb 09, 2013 10:53 pm 
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You are not going to be able to tweak the LPG ECU into making more power from your engine but it will probably need a re tune to acomadate the modifications you have made.

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PostPosted: Sat Feb 09, 2013 11:25 pm 
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Thanks Classicswede - thats a pity I'm assuming that's because the ECU on the Emer system is locked? I did notice on Ebay that there was some software tuning items available for Emer LPG and wasn't sure of their worth or otherwise. Could you advise?
The tune was done after the mods and is based on data logging of other similar vehicles running the LS1 with gas. Ignition timing maps were probably the biggest changes over the factory settings with more advance being put in at low and high RPM (mid-range only 1 degree more advance or so) resulting in a more linear power delivery. Also a lean cruise setting was applied and rev-limiter raised to 6500rpm.


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PostPosted: Sun Feb 10, 2013 12:00 am 
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The Emer ECU isn't locked but it isn't something you can tune for more power. It piggybacks onto the petrol ECU so any mods done to the tune on petrol will be reflected when on LPG. Basically the gas injectors need to open for slightly longer than the petrol ones. All the LPG ECU does is intercept the pulses from the petrol ECU, adds a bit and fires the LPG injectors for the required amount of time. The mixture is still being controlled by the petrol ECU even though you are running on gas, so if you were to alter the tuning of the LPG timings, then the petrol ECU would detect an incorrect mixture and adjust the petrol injector pulses which would then adjust the LPG times.

The only place where you may make a slight gain is in the ignition timing. As LPG has a higher octane rating than petrol, you can run more advance on LPG than on petrol.

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PostPosted: Sun Feb 10, 2013 2:08 am 
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Thanks also to Gilbertd - seems I've run my race down this avenue and there's nothing more here to persue - which is a lot better than finding out after I'd spent more money :) Hopefully the upcoming modification of an over the radiator cold air intake will facilitate further gains. The vehicle will need to be retuned in a MAFLESS format (which the tuner said is a simple job to pick up air flow from other sensors) as the OTR doesn't have room for the MAF. I'll need to drill a hole in the OTR putting in a separate air intake temperature sensor as the current ATI sensor is incorporated in the MAF.
I've never owned a injected gas vehicle before, only mixer types. I know from experience when I tried to tweak something on those gas performance was sometimes compromised, so it'll be interesting to see the result...


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PostPosted: Wed May 22, 2013 8:22 am 
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Just a follow up to post info that may or may not be of benefit to anyone.
OTRCAI fitted. John from Vengeance tuning, Sydney NSW changed tune, picking up MAP sensor and separate IAT sensor instead of MAF which was removed. Data logging session involved with several full throttle runs in 1st gear to 6500 rpm (once) most to about 6200rpm on both lpg and unleaded 98.
Car has jumped significantly in performance and revs really quickly indistinguishable on either fuel. Hasn't been dynoed but given as I can physically sense a significant boost I'd guess its at least in the order of 20kw. Impossible to ascertain whether custom tune or OTR is responsible for this gain but I strongly suspect its more the tune than anything else. Consumption has dropped by about 0.3L/100kms during economical driving to and fro work.


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PostPosted: Wed May 22, 2013 10:38 am 
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I suspect it is the combination of the mods and supporting mapping is where the power and tgrottle response has come from. Improved fuel consumption is most likely due to not needing to press the accelerator down as far now.

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DIY LPG Kits

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