Analogue Sensor jitter/jumping after car warming up

[6nfanatic]

Hi,
i have strange thing with my Sensors. Im using two Bosh Temp/Pressure sensor. One for fuel pressure and one for Oil Pressure / Oil Temp.

While mapping, i noticed the Fuel Pressure was jumping between 2,6bar and 4,2bar. I changed the whole puel pump assembly inc. the pump and it didnt changed a thing.
I logged the cold start a few days ago and noticed that on the first 4 Minutes, the Sensors are very stable, AN0 (FuelPress) is very flat.
And after like 4 Minutes, the ignition starts to move the sensor is reading the jumping values. Look at the attached datalog or the pic.

Ive connected the +5V Source from the TPS wire and Ground is on the Kprov4 Ground on the additional harness.

What could be the Problem?

[Spunkster]

Your battery voltage is fluctuating by half a volt constantly. You may want to look into that first.

[6nfanatic]

why is that?

[Spunkster]

It may resolve the other issue you are having.

[6nfanatic]

no i mean how to check what could cause the voltage jitter.
Thanks

[Spunkster]

You will have to go over the wiring and possibly test the ECU in a known working vehicle and use process of elimination. Typically this is an issue with grounds or the alternator itself or how things have been wired.

[6nfanatic]

How can I improve the ground? Should I run more wires from the cylinder head to the chassis?

[Spunkster]

Make sure they are in the correct location and that they are not corroded or painted.

[Furious]

Have you found the issue why voltage is fluctating?
I have simillar case that oil pressure signal is very noisy. Is there a way to smooth it using some resitors or capacitors?
Thanks

[6nfanatic]

Hey no. I tried to wire it differently and completele seperate from ignition loom and stuff and tried the different grounding on the ecu but it didnt changed a thing..

I dont know where the Ground issues are. Its a fulkly build race car with stripped wireloom, welded cage and stuff. Its not possible to have the OEM groundlocations so im kinda stuck.
It sucks to be fair.

[6nfanatic]

Hello,

i cant find the issue. You say i have a grounding problem. But how can i fix it? Can i put more ground wires from the engine to the chassis to fix it?

Im starting to fed up with kpro, never had those issues with the link g4x :(