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Piggyback use with closed loop fuelling.


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Been thinking about some future plans using a piggyback on a 4efe + t build.

I know alot of conversions are out there and would like peoples advice / experience regarding the stock ECU and stock O2 sensor when it comes to closed loop fuel trims.

As far as I know if fuel is added with the piggy back in an area of the map that the stock ECU controls with closed loop O2 sensor feed back it will remove the added fuel using a short term fuel trim, if the symptoms persist it will add a long term fuel trim nullifying the added fuel.

How do people get round this? Do you remove the stock O2? Do you just floor it everywhere to force the ECU into open loop mode? Can you add a small amount of fuel without the fuel trims occuring?

Any help is welcomed.

 

Cheers. 

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I've added a screw in tube to the exhaust lamba\o2 flange, so only the very bottom of the standard 4efe O2 sensor sees the exhaust gas stream positioned in the standard 4efe ep91 exhaust location on the jap speed system. this creates a leaner reading from the 4efe O2 sensor so far it's working nice allowing the closed loop operation. I'm running a high flow proformance cat also on a aem piggy back ems. I'm data logging the O2 sensors voltage\lamba output. When mot time comes I remove the tube so the lamba sees the full stream. 

I hit a slight issue when I moved up to 1bar of boost pressure and a heat range 7 plug the co emissions jumped up so did the egt =increased unburnt fuel exiting the cylinder at levels that would reduce the cats in service lifespan. 

Edited by Sam44
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Thanks Sam,

I'll be using an Ecu master DET 3 + on my project in piggyback mode so planning on adjusting the Map sensor voltage for fuelling changes (the det 3 can only adjust one analogue input other than timing) and will be retarding the ignition as required. It can also control a boost solenoid. I could hook up the stock O2 as well for logging purposes.

I think the AEM FIC has an O2 map that allows control of the O2 sensor output voltage to the toyota ECU? Used for closed loop specifically.

 

Edited by Claymore
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9 minutes ago, Claymore said:

Thanks Sam,

I'll be using an Ecu master DET 3 + on my project in piggyback mode so planning on adjusting the Map sensor voltage for fuelling changes (the det 3 can only adjust one analogue input other than timing) and will be retarding the ignition as required. It can also control a boost solenoid. I could hook up the stock O2 as well for logging purposes.

I think the AEM FIC has an O2 map that allows control of the O2 sensor output voltage to the toyota ECU? Used for closed loop specifically.

 

Yeh the aem does do this but it's not a faultless system by any stretch of the imagination this is because I'm running a cat for euro emissions standard. I need to keep the cat healthy and use the lamba and closed loop as much as I can (Road proformance) 

I've just finished fitting a det3 to a eg civic d16y8 engine running the later coil on plug loom ECU, on a  turboed.

I'm very impressed with it. If you need any help setting things up give us a shout. We use the pmw tables to activate the VTEC solenoid as it was also running a aftermarket cam. 

Great ECU this vehicle is logging data also onit.

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