I have a 1991 3.9 V8 fitted into a Series 3, the engine currently has fitted a hotwire injection system. The engine is timed to TDC, new spark plugs and gives a good spark. It has the standard range rover in tank pump.
The engine starts and runs up to temprature but present the two very strange problems. Firstly the engine has a flat spot at just above tickover, if you push the throttle it's like the management system takes a little time to respond and it will splutter, do this enough times in quick sucession and the engine will stop. Second issue, if the engine is turned off from the key it will start without issue. If the engine stalls or is otherwise stopped without using the key it will not start. There is a good spark during this period.
The following has been replaced;
ECU
Engine coolant sensor
Fuel thermistor
AFM
Throttle Pot
The idle air valve has been removed, cleaned and refitted. If removed you can see it moving out and back in again.
The battery presents around 14v when running.
I'm currently preparing a pair of SU's and a manifold to fit as I've run out of ideas with the EFI.
Any suggestions welcomed please!