Subaru H6 set up

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madscot286
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Subaru H6 set up

#1 Post by madscot286 » Thu May 25, 2017 7:37 pm

Hi. Been a while since been on here after very helpful advice setting up a Toyota Celica on LPG which ran very well.

Have inherited a Subaru Legacy 3.0 H6 with a mixture of used and new LPG parts fitted but not working. Tank is used but within date (2010). Vapouriser is Magic 3 (new) and injectors are Valtek Type 34 (used). Controller is Stag 300 Plus (used dated 2010). Wiring is all in place. Water and all gas hoses are new.

On Petrol
Pinj is 2.6
Gas pressure is 0.72
MAP is 0.27
Gas temp is 60
Reducer temp is 80
Lambda is between 0.20 and 0.31

Have been trying to run autocalibration but throws up following errors:
When 3 cylinders are switched to gas throws up error "RPM value: 400 is too low" (normal rpm is 660; at this point in autocal it drops to 580)
Pinj is 3.3
Gas pressure is 1.2
MAP is 0.32
Gas & Red temp same
Lambda same
No reading for Ginj - was expecting to see something but maybe shows later in autocal process?

When autocal switches to all 6 cyl the engine stalls and error message "Collector pressure: 0.71 is not correct".
At that point readings are:
Gas p 1.14
MAP 0.59
Pinj & Ginj obviously 0 as stalled
RPM at stall 620
Lambda at 0.04 & 0.71

Gas is getting through to the injectors (loosened one of the rail hoses and usual "pssh" sound and gas smell) so vapouriser seems to be working.

Any guidance on what to troubleshoot and in what order would be gratefully received.

LPGC
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Re: Subaru H6 set up

#2 Post by LPGC » Fri May 26, 2017 7:58 pm

Where did you connect reducer vacuum reference and pressure sensor vacuum reference pipes?
Obviously when engine is stalled map should be 1, because a stalled engine doesn't pull any vacuum...

How are you reading lambda?

Simon
Full time LPG installer
Servicing / Diagnostics / Repairs to all systems / DIY conversion kits supplied with thorough tech support
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madscot286
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Posts: 16
Joined: Mon Apr 09, 2012 5:56 pm

Re: Subaru H6 set up

#3 Post by madscot286 » Fri May 26, 2017 8:39 pm

Hi Simon - thanks for response.
The reducer vaccum hose is connected from top of Magic 3 to T connection with hose to MAP sensor (-ve) and other hose to inlet manifold.
MAP sensor (+ve) hose connected to combined temperature and pressure sensor fitting plumbed into gas outlet hose from reducer output to injector rails. It's plumbed in before the filter, if that makes any significant difference.
Lambda reading is taken from signal wires to what Subaru manual calls the rear oxygen sensors but ahead of the catalytic converter.
Hope that's all explained ok.

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Re: Subaru H6 set up

#4 Post by LPGC » Sat May 27, 2017 11:18 pm

Where on the manifold did you connect vacuum, did you tap a hole yourself?
So you're reading lambda voltage using the LPG system facility. Got to question why lambda would be between 0.2 and 0.3 on petrol(?). What year H6?

Simon
Full time LPG installer
Servicing / Diagnostics / Repairs to all systems / DIY conversion kits supplied with thorough tech support
Mid Yorkshire
2 miles A1, 8 miles M62,
http://www.Lpgc.co.uk
Twitter https://twitter.com/AutogasSimon
07816237240

madscot286
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Joined: Mon Apr 09, 2012 5:56 pm

Re: Subaru H6 set up

#5 Post by madscot286 » Sat May 27, 2017 11:27 pm

Tapped into manifold on top centre section just after throttle assembly to get vacuum for MAP.
Tried autocal again today after long run and engine hot and lambda reading was 0.7 and 0.8. Still stalled at same point in process.
H6 is 2006 plate car.
Any ideas what needs resolving?

madscot286
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Posts: 16
Joined: Mon Apr 09, 2012 5:56 pm

Re: Subaru H6 set up

#6 Post by madscot286 » Sun Jun 04, 2017 5:14 pm

Hi. I've rechecked all the wiring to ECU, injectors and sensors but still have same error messages showing up during autocal e.g. RPM too low; collector pressure 0.71 is not correct.
As the Stag 300 6 Plus ECU is used wondering whether this might be duff and need replacing?
Do MAP sensors ever fail and need replacing?
Also wondered the same with the tank and multivalve (originally fitted 2010) and whether gas pressure is OK (i.e. error message talks about collector pressure being incorrect).
Any assistance much appreciated in advance.

madscot286
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Posts: 16
Joined: Mon Apr 09, 2012 5:56 pm

Re: Subaru H6 set up

#7 Post by madscot286 » Mon Jun 26, 2017 1:12 pm

Hi.
So - I got the system working on the Subaru (woohoo!). Turned out the wiring loom to the injectors had been connected up wrong.
Engine now switching to LPG OK and running smoothly through the rev range.
However, on autocal I know the multiplier MAP on the Stag system should be 1.2 on left hand side and 1.0 on the right hand side.
I drilled nozzles in 0.1mm increments from 1.8mm (software said "nozzles too small") to 2.2mm but multiplier was at 1.8 to 1.6. Tried increasing Vap pressure from 1.0 to 1.3 but only reduced multiplier to just under 1.6.
Drilled nozzles in increments to 2.5mm with Vap at 1.3 bar but could only get multiplier to 1.5 on LHS and 1.3 on RHS. Tried drilling nozzles incrementally to 3.0mm but can't get multiplier to go below 1.4.
Magic Jet 3 vap doesn't seem to go higher than 1.35 bar so can't increase to, for example, 1.5 bar (as seen on some other similar threads).
Got a second set of nozzles to start again but wondering if I need a different vap from the Magic Jet? I've had a previous car use a Magic Jet really well (180hp Celica) but wonder if it isn't up to the task for the Subaru 3.0 H6 at 240hp, even though Magic Jet spec says rated to 250hp.
Any advice on next steps?
Many thanks

LPGC
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Re: Subaru H6 set up

#8 Post by LPGC » Mon Jun 26, 2017 1:59 pm

Don't just increase physical pressure, also increase reference pressure (done is software).

Start with 2.5mm nozzles. If pinj is much below 3ms with warmed engine idling on petrol (and particularly if pinj peaks at around 12ms instead of 16ms at full load as you go through the rpm range) then depending on what injectors you have fitted the slope of the map may be different to what might be expected, it may need a larger multiplier at idle than 1.2 but still you don't want multiplier of much over 1 at 12ms plus.

MJ should cope with 240hp, how much does pressure fall off when at full load?

Simon
Full time LPG installer
Servicing / Diagnostics / Repairs to all systems / DIY conversion kits supplied with thorough tech support
Mid Yorkshire
2 miles A1, 8 miles M62,
http://www.Lpgc.co.uk
Twitter https://twitter.com/AutogasSimon
07816237240

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