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Closed loop on idle

Carl Richards

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I have a 98 GC8 impreza JDM  , in 2001 I had a G1 link ECU fitted and mapped. It's been perfect. Recently I fitted a wideband oxygen sensor with AFR gauge and wideband and simulAted narrow band outputs.

The ECU does nearly everything I want but there are two areas I'd like to improve:

1. Close loop on idle - can the ECU support this modification

2. Wideband support - I guess I would have to replace the existing narrowband sensor with the simulated wideband signal?

And lastly a question about Knock, my knock performance looks ok, but what does the ECU do when the knock threshold is exceeded?

Many thanks 


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Hi Carl,

In response to your questions.

1) Which Link G1 do you have? The features they had varied a fair bit. I'm not aware of any supporting closed loop idle control.

2) You could use the simulated narrowband setting and feed this into your G1. This should give you a more accurate signal.

3) The knock control should retard your ignition timing when knock above your threshold is detected.



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Thanks Scott,

The ECU supports only full time open loop or closed loop. I wondered if there had been any updates to support closed loop on idle

The ECU is a Possumlink WRX MY98 & 22B. I'm not near the car at the moment so I can't get additional info.

Having connected a wideband gauge and logger I was surprised to see an AFR of 11 on tick over with a professional map Everything works fine but I'd improve the idle performance and fuel consumption.

Currently the ECU is set for open loop.


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Hi Carl,

Because the G1 is now so old we no longer do any updates for it. If you wish to gain the additional features the only solution really is to upgrade your ECU to the current generation.

By tuning your AFR's some you may be able to gain better fuel consumption. Be careful not to go too lean though.


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