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Spi Over Fuelling - Lambda Not Switching


Best Answer MiniJosh92 , 01 November 2019 - 05:59 PM

Decided to check the wiring this afternoon and tested it all between the lambda plug, relay and ecu, all was well, plugged everything back in and it it started switching perfectly and emissions are bang on! Must have been a dodgy connection on one of the three plugs.

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#1 MiniJosh92

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Posted 31 October 2019 - 06:29 PM

Good old spi emissions issues - usual story, fails MOT, found split vac pipe elbows. Replaced all those, check on code reader and lambda not switching, constant 1.8V.

 

New Bosch lambda fitted and still get a constant lambda reading of 1.8V. Also given it a full service.

 

All other readings are as to be expected, coolant temp, MAP etc. Have changed lambda heater relay and tested that is getting 12V at the plug. If I pinch the fuel supply line just the right amount to lean it off the lambda starts switching as it should so proves it works. It runs and drives very well which is not what I would expect with a lambda reading of 1.8V!



#2 genpop

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Posted 01 November 2019 - 08:29 AM

Change ecu with a good one (from other car), just for testing!

Disconnect charcoal canister.

Disconnect engine breather.

Test fuel pressure.

Clean the O2 bypass. (Very difficult without taking off the O2 valve, but you could press some cleaner through the bypass).



#3 humph

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Posted 01 November 2019 - 08:53 AM

I have had this issue in the past, among various others. The issue was eventually tracked to a broken feed wire in the loom which meant that the sensor was working at times and not at other. The loom in the area of the fuel trap rubs between the throttle body/inlet and the bulkhead leading to breaks.



#4 MiniJosh92

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Posted 01 November 2019 - 05:59 PM   Best Answer

Decided to check the wiring this afternoon and tested it all between the lambda plug, relay and ecu, all was well, plugged everything back in and it it started switching perfectly and emissions are bang on! Must have been a dodgy connection on one of the three plugs.






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