Open or closed loop?

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Open or closed loop?

Postby The_blue » 27 Jun 2010, 17:18

My van has an open loop conversion, would it pay to adapt this to closed?
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Re: Open or closed loop?

Postby Ian Hulley » 27 Jun 2010, 22:09

Honestly you'd do well to leave this to the proffesionals.

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Re: Open or closed loop?

Postby The_blue » 28 Jun 2010, 07:11

lol that might be true!

It was only a question, i was wanting opinion on what setups folks had and why? :)
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Re: Open or closed loop?

Postby silverbullet » 28 Jun 2010, 21:23

My 2.6 SA was converted recently, I'm getting 21mpg on gas with an open-loop system, keeping it legal and most of the mileage on motorways (300 miles every weekend) I will upgrade it to closed loop once I've got a new exhaust as the range on a 52 litre tank is only about 200 miles. Not enough. Can't help thinking that fuel is still going out the tailpipe.
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Re: Open or closed loop?

Postby toomanytoys » 11 Jul 2010, 16:40

Does your van already have lambda control?
What MPG are you getting on gas compared to what you were getting for the same driving on petrol?

Same questions for Silverbullet?

What often happens is the mpg wont get better or only by a small amount.. drivability can improve though.. but it all depends on how well set up the "open loop" is... :wink: :wink: closed loop lambda control isnt the "be all and end all".. its needed on newer vehicles with cats to ensure the cat is fed with a consistant mix, so as not to bugger it up...
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Re: Open or closed loop?

Postby Ian Hulley » 11 Jul 2010, 17:24

silverbullet wrote: the range on a 52 litre tank is only about 200 miles.


That sounds about right to me ... I don't know what you were expecting ?

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Re: Open or closed loop?

Postby The_blue » 11 Jul 2010, 19:45

toomanytoys wrote:Does your van already have lambda control?
What MPG are you getting on gas compared to what you were getting for the same driving on petrol?

Same questions for Silverbullet?

What often happens is the mpg wont get better or only by a small amount.. drivability can improve though.. but it all depends on how well set up the "open loop" is... :wink: :wink: closed loop lambda control isnt the "be all and end all".. its needed on newer vehicles with cats to ensure the cat is fed with a consistant mix, so as not to bugger it up...


No lambda, it's an early LT35.

It drives fine just want to make sure its as good as possible all the time.
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Re: Open or closed loop?

Postby silverbullet » 11 Jul 2010, 23:25

Like wise, the 2.6 doesn't have lambda feedback to the ecu. I reckon that it returns about 25-26 mpg cruising at 65 on petrol, on a 150 round trip; but on gas it's returning 21, which is less than exciting for a 2wd tin-top bus (not a heavy camper) not being driven like I stole it...that's what the Scooby is for :D
The cutting out at the lights (when hot) and random blowbacks in the hot weather suggest that it's too rich.
PS the temp gauge is in the normal range for petrol. No overheating.
Also when the tank gets low (last LED) I have had the unpleasant experience of putting my foot own to overtake (yes you can do that in an SA) and the thing just fluffs and hesitates. Hasty switch to petrol and all's well again. When I pulled up to re-gas, only got 35 litres in! What's going on there then? Can't use the last 5 litres of gas either?
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Re: Open or closed loop?

Postby The_blue » 12 Jul 2010, 09:17

The cutting out at the lights (when hot) and random blowbacks in the hot weather suggest that it's too rich.

viewtopic.php?f=3&t=70824

Overfuling, been there, done that ;)

Blowbacks sugest timing as well. If it's firing into the carb it's because the inlet valve is still open on the up stroke.
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Re: Open or closed loop?

Postby silverbullet » 12 Jul 2010, 12:08

The 2.6 is externally identical to the 2.5 petrol T4 motor. Motronic with batch-fired injectors, alloy inlet manifold. I cannot find out what the correct timing figure should be...any suggestions?
I know that I should optimize for LPG as petrol is only for start-up and last resort.
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