Diagnostics Doctor
Q I have just swapped the engine in my 2011 Citroën C1 – a base model without central locking – with a three-cylinder 1000cc Toyota 1KR-FE engine complete with inlet manifold and sensors salvaged from a 2009 Peugeot 107. No other electrical parts were changed.
I filled the new engine with oil, left the injectors unconnected, removed the spark plugs and, after connecting the battery, turned over the engine to distribute the oil and build up oil pressure. Once the oil pressure warning light extinguished, I disconnected the battery, fitted the plugs and coil packs and plugged in the injectors. I reconnected the battery and tried to start the engine. I could hear the fuel pump running, but while the engine cranked fine, it would not start. At this time, I noted that only the amber EML light and red battery light on the dash were illuminated.
When I connect a basic OBD-II scanner, all the dash warning lights appear and the engine will start. However, as soon as the scanner is disconnected, the lights go out, apart from the battery and EML lights. The effect of the scanner is immediate, with no perceptible delay. I have tried both keys and the results are the same. I have tried turning on the ignition and waiting for a few minutes as I read that the system can take a up to a minute to initialise, but this made no difference. Surprisingly, simply connecting the interface cable of an Autel MS509 without the scanner allows the car to start – is there an interface in the lead and some initialisation occurring?
The OBD-II scanner appears to indicate that everything is OK, with no codes pending or stored, and live data can be read. Is it possible some corruption has occurred by connecting and disconnecting the battery? What is the meaning of the two dash lights being illuminated? Could it have something to do with the immobiliser? John Butterfield
A This problem is not as rare or as strange as it might first appear. I have come across it on several vehicles and the reason is normally due to either a poor earth connection at some point or a failed live connection. The act of plugging in the scanner is to provide a circuit for the earth to the ECU or the feed. I would start by checking the sections of the loom which were disturbed during the engine swap and ensure the coil packs are earthing. From the data I have, all three coil packs use one earth point on the engine, so this would be the most likely place to check. Using an ohmmeter on the coil pack plugs, the three wires on the coil pack are numbered 1, 3 and 4, with 1 being the supply voltage, 3 the ECU connection and 4 the earth connection. As the engine does spin over at a reasonable rate, I would expect the main earth lead to be connected correctly, but it is always worth rechecking. I am not sure which engine loom you have used, but there may be a slight variation which means that the components are not getting correctly earthed.
I am also assuming that the replacement engine was running before it was removed from the donor vehicle. If not, one of the engine sensors may be at fault, but the most likely scenario is that one of the earth connections is not making a good contact.