NOVEMBER 2023 AFTERMARKET 25 Next month: A Citroen C3, £750 for an injector and NOx sensor: Good value or are VMs driving motorist to EVs? out. Please refer to Fig.1. The PCM control was consistent with other known direct injection variants, utilising PWM control. Satisfied with this confirmed value, I reflected on something interesting on the internet regarding this exact pump type failure. Apparently, if the pump was fitted with the CAM on full lift, it could bend or break the plunger or CAM follower. To rule this out I removed the HP pump and examined the two CAM lobes and plunger. Everything was okay. Solid knowledge At this point I was about to advise ordering a new pump. Maybe it was the £900 price tag or my guardian angel (experience) that directed me to confirm priming flow and pressure before taking the plunge on a new part. Out came my trusty hydraulic test gauge. In order to attach it safely, I interrupted the junction by the lower chassis rail. Cranking the vehicle, the gauge indicated zero pressure. This was strange, as the serial data indicated 6.9 bar. There it was in a nutshell. Did I lose my way, was I over cautious, or misled by inaccurate serial data? You decide I have already blamed my mistake on not following my own advice; Measure and verify always. A new in-tank pump was fitted. I also checked PCM control using my Pico and re-checked low pressure with the gauge at 4.5 bar. Serial data was still at 6.9 bar. Please refer to Fig.2, which shows PCM control of the low-pressure pump. Then look at Fig.3, which shows the gauge fitted to the priming circuit, and the actual pressure value. The vehicle now started and ran, but with a slight uneven balance. New plugs were previously fitted, so I scoped the ignition profile confirming good spark burn time and primary current profile. Armed with this solid knowledge, I had no hesitation in advising a probable injector delivery issue. The customer agreed and following further and quite extensive swap-out time to reach the injectors, I was able to bench test and confirm that No.3 cylinder flow was down by almost 25%. Following an ultrasonic clean in our ASNU bench, balance was restored and a very smooth engine response was presented to our customer. The labour alone was £1,500, but this is where we are and exemplifies my point at the start of this story; Get your ducks in a row or suffer the cost from your own pocket. Fig. 2 www.aftermarketonline.net Fig. 3
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