LPGTECH map changes between petrol and gas

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LPGTECH map changes between petrol and gas

#1 Post by jacckk » Wed Nov 24, 2021 6:30 pm

I noticed today that the MAP value changes when switching between gas and petrol. On Petrol it's around 0.57bar, on gas it's up at 0.65bar. It's using the LPGTECH PTS01 which is a MAP sensor and gas pressure sensor.

The map value switches as soon as the system attempts to run on gas, before it even starts pulsing the injectors. To check if this was a real change in the MAP reading I disabled all of the gas injectors and then switched it to gas. As soon as I switch to gas (even though the injectors are disabled so it's still on petrol) the MAP value also changes which would suggest it's not real.

Has anyone seen this before? I'm assuming it's not normal.

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Re: LPGTECH map changes between petrol and gas

#2 Post by LPGC » Wed Nov 24, 2021 7:25 pm

It's very likely that the current draw for the LPG solenoids is affecting the reference voltage (or voltage at earth) for the pressure sensor.

Use a multimeter to test the voltage at the pressure sensor earth, power feed and on it's signal wire.

Any problem with the solenoids (e.g. partial internal short circuit causing them to pull too much current)?
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