Another fun one… Peugeot Boxer 1994 running problem & no diagnostic communication. 2500RPM the engine was surging up and down the rev range. On the scope ( blue line in the picture ) was the earth for the crank sensor this had a huge amount of interferance / was dropping. We traced the fault back to sevral earth faults on the vehicle. This was all due to age and corrosion.
First was the chassis to gearbox strap, 2 x ECU earths on the engine block were cleaned, Battery negative cable to body work. Once we cleaned all the earths, the vehicle started to run alot better however it still had no communication to diagnostics and the outside ECU casing wasn’t showing an earth. This means the earth track inside the ECU is damaged. This is due to the poor earths on the vehicle & the spiking of voltages.
The reason for the poor running is the ECU was finding a route / path to earth through sensors and brackets within the engine bay. We also run an additional ECU earth the the body as a fail safe in the future. When doing Ohms checks on the engine loom we also found Injector 3 had high resistance. As such we replaced the plug on this injector.
This vehicle will be good to go once the ECU has been repaired and put back in the vehicle. If you would like to talk about your vehicles running issues call us on 07340341790.