DTAForum.com - a forum for the DTA ECU

The fuel map on my engine is set up to have a fuel uplift at 700 rpm on zero throttle opening with normal idle like yours at 900rpm. This means that as the engine speed drops below 900rpm fuelling is increased to prevent the engine stalling when the throttle is suddenly lifted off.

Well I did 360 miles in the Lotus yesterday; it was car designer Oliver Winterbottom’s funeral in Wymondham yesterday and a number of us with ‘his’ cars formed a guard of honour following the cortège. So I’m delighted I and the car were able to be there. It started and ran better than ever.

Good news. I had time to check the switched power to the relay today- 7.5v! It dropped to a lower figure while cranking such that it was not always enough to activate the relay. This circuit came off the vehicle wiring loom but I couldn’t easily trace it back so ran a new wire from a spare switched ...

Don't want to teach you to suck eggs, but are you confident the 12v supply you're using to feed the ECU remains "live" in the cranking position? That is one thing I’m checking. When I got the engine started a few days ago, the real time display showed a sudden and very brief drop to 0v af...

Back again and mystified. Having reworked the power supply such that I'm feeding off a battery live terminal on the fusebox (via an inline 20a fuse), I have been trying to start the car. Voltage across battery terminals: 12.4v Voltage on real time display with ignition on: 12.4v The red band on the ...

Looks like it was a combination of a dodgy USB extension cable and a dirty power supply. The S40 lives again.

Thanks katana,

the s40 wiring diagram shows the fuel pump relay connecting to pin 1 so I guess (but don’t know) that if the ecu is dead no connection would be made.

Have taken apart and reconnected the serial and usb cables several times. Maybe I’ll get a new usb cable and try that.

Thanks, Richard

The car won’t start and the S40 can’t be seen by my laptop (usb connection). I’ve checked that the power supply is ok, and the earth is ok. The main power relay and fuses are all ok. The fuel pump cuts in when the ignition Is switched on. Are there any other tests I could run to check the ecu itself...

Thanks Paul - map sent

Richard

That looks a superb conversion! As I expect you know, there is common history between the Vauxhall slant 4 engines and the Lotus 9xx series. Lotus used the Vauxhall block initially for development and competition, and I'm pretty sure Lotus subsequently ran 907 testbeds in a VX 4/90 and a CF van! The...