Simtek ecu and lambda sensor
 

Does the simtek ecu on an early classic sti use or rely on the original lambda for anything at all???

Got serious overfueling issues and cant seem to work out why

Thanks in advance

simtek can be set to use it or not, would of thought it would be set to use it

Yes if enabled will use it within pre-defined load and rpm limits to fuel correct to lambda one. Has it been mapped recently? If you are having fueling problems or you suspect so then pop it back to the Simtek mapper that sorted it, or if they can't sort it give me a tinkle as I'm not too far away from you.

Graham

Thanks for the replies, pm sent to engine mapper

Will it affect the car detrementily if i unplug the lambda sensor, will the simtek then revert to closed loop lambda?? Will that improve the fuel economy until i can get the car sorted properly.

Anyone??

If you unplug it you will disable closed loop as the ECU needs the signal to run in closed loop. With it unplugged it should go into error mode and the ecu will run with whatever pulse width is in the base fuel map.

Is it idling smoothly?

It wont know it is not connected as 0 to 1volt all valid signal.

It will over fuel unless switch off in ecu

No, the idle is far from smooth, very lumpy and the car is just horrible to drive on light throttle, very very jerky, im gonna have to get it looked at as soon as possible so that i feel safe with using the car to get to work and back until i can get it sorted fully.

A new lamda is very easy to fit. Its the rear one you need. Its about 30mins max to fit.

Sorry just re read and its a classic so may not be the rear one. I was refering to new age. Maybe different on a classic

Yeh, just the one on mine in headers i believe, however, ive been out of work and only just started a new job so cash is tight, was looking for a quick fix till i can afford to sort properly.

The Lambda sensor on your car was originally located in the headers collector close to the driver's front wheel. Sometimes these narrow band Lambda sensors have been relocated to the downpipe and the hole for the Lambda sensor in the collector bunged.
Do not buy a dealer Lambda sensor as it is a big rip off but you can get one for £50 or £60 from Andrew Page or similar motor factors but ensure it is a Bosch item.
The ECU runs in closed loop when off boost and the purpose of the Lambda sensor is to allow the fuelling to be around 14.5 AFR during off boost operation.
If your Lambda sensor is defective you are now grossly over fuelling and a new Lambda sensor should be fitted sooner rather than later as you are probably suffering bore wash at present which is not a good thing.
Changing the Lambda sensor is relatively simple.