Golf Mk2 with CANEMS ECU: fuel-system and idle work.

Golf Mk2 with CANEMS ECU: fuel-system and idle work.

The owner was converting a former track car for road use. It had individual throttle bodies and a swirl-pot fuel system in the boot. On arrival, low fuel pressure prevented it from idling, and the fitted rail gauge did not agree with our test gauges.

We fitted a regulator and gauge in the engine bay. Once pressure was restored, the return hose leaked, so we ran a new return line to the tank. We balanced the throttle bodies and used a Bosch gas analyser and exhaust oxygen sensor to check fuelling in the dyno cell. Fuel pressure was set around 2 bar, and we adjusted idle settings and ignition scatter.

The ECU was an early CANEMS unit. After speaking with the manufacturer, we installed Windows XP to run its older .NET 1.1 software. We recommended a wideband oxygen sensor and AFR display, with ECU feedback, and discussed a newer ECU. The owner declined those changes.

On a later visit the engine was running rich and the fuel pressure had changed. We reset it and repeated the sensor recommendation. Months later, another inspection found changed fuel pressure and lower compression in one cylinder. We advised the owner to stop driving and bring the car in if it was running poorly.

The billed work covered the fuel-system changes, dyno fuelling checks, throttle balancing and idle setup. Labour totalled £375; subsequent visits were not billed. The case shows why a modified fuel system needs pressure checks and ongoing AFR monitoring.