Silicon Filled Fuel Gauge Problems!

Today I

  • Changed the FP down from 16PSI to 10PSI. 10PSI is what the injector is originally rated at e.g. 55lb/hr. or 575cc/min which at 85% duty cycle and a BSFC of 0.5 is good for ~94BHP. More than enough for my engine! Edit: Forgot to say why I’ve reverted back to 10PSI from 16. Reason is that 10PSI gives me a longer opening period of the injector. I’ve read in several books on the A series engines that they like a coarser atomisation of the fuel along with high gas velocity.
  • Obviously had to re-check the VE table, did so using the auto tune live function.
  • Car seems to be OK, but don’t have lot of time to tune it as I’m on a late shift today
  • Checked the fuel pressure again, gauge read 5PSI. WTF!!
  • Did some research on internet; it seems that silicon filled gauges change reading because of the pressure differential between internal and external pressure. This is caused by the silicon/gauge heating up because of fuel/under bonnet temperatures. The gauge is not vented and hence pressure builds up putting pressure on the gauge mechanism.
  • What to do? Mmmm.. I ordered a 100PSI fuel pressure sensor, that I’ll screw into the FPR and connect to one of the spare ADC (Analogue Digital Converter) inputs in the MS ECU. I will then create/configure a Fuel Pressure Gauge within the TunerStudio software. This will be a lot accurate hopefully! Edit: And also gives me the ability to log the FP whilst driving, so I can look out for FP sags etc. A lot easier than sticking my head under the bonnet whilst driving the c##p out of her!

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