New oil pressure sender reading too low
08-09-2021, 12:35 PM
#16
Archive Gatekeeper
Rennlist Member
Rennlist Member
Kroon has just released a replacement for the 3 pin pressure sender connector:
https://www.facebook.com/kroon.wireharnesses
https://www.facebook.com/kroon.wireharnesses
08-09-2021, 12:51 PM
#17
Drifting
Thread Starter
Kroon has just released a replacement for the 3 pin pressure sender connector:
https://www.facebook.com/kroon.wireharnesses
https://www.facebook.com/kroon.wireharnesses
Earlier today I ordered a new sender from Porsche. Almost 3x the price of the NOS I picked up on eBay, but if it reads more accurately will be worth it.
Last edited by StratfordShark; 08-09-2021 at 12:55 PM.
08-19-2021, 11:39 AM
#18
Drifting
Thread Starter
New sensor arrived from Porsche today so I've just checked static resistance before installing later.
The NOS one I installed (to replace original which had small leak) had static resistance 5 ohm, and 96 ohm cold idle, and read 3 bar cold idle instead of normal 5 bar. When car was fully warmed it was reading 3 bar when driving, and around 1 bar idle. The data sheet I have for the sensor says resistance should range from 10 to 184 ohm. The NOS sensor was dated 2009.
The Porsche-sourced sensor dated June 2020. Static resistance is 9 ohm so I'm pretty sure the gauge will now read correctly after it's installed.
The NOS one I installed (to replace original which had small leak) had static resistance 5 ohm, and 96 ohm cold idle, and read 3 bar cold idle instead of normal 5 bar. When car was fully warmed it was reading 3 bar when driving, and around 1 bar idle. The data sheet I have for the sensor says resistance should range from 10 to 184 ohm. The NOS sensor was dated 2009.
The Porsche-sourced sensor dated June 2020. Static resistance is 9 ohm so I'm pretty sure the gauge will now read correctly after it's installed.
Last edited by StratfordShark; 08-19-2021 at 11:42 AM.
08-19-2021, 12:03 PM
#19
Rennlist Member
New sensor arrived from Porsche today so I've just checked static resistance before installing later.
The NOS one I installed (to replace original which had small leak) had static resistance 5 ohm, and 96 ohm cold idle, and read 3 bar cold idle instead of normal 5 bar. When car was fully warmed it was reading 3 bar when driving, and around 1 bar idle. The data sheet I have for the sensor says resistance should range from 10 to 184 ohm. The NOS sensor was dated 2009.
The Porsche-sourced sensor dated June 2020. Static resistance is 9 ohm so I'm pretty sure the gauge will now read correctly after it's installed.
The NOS one I installed (to replace original which had small leak) had static resistance 5 ohm, and 96 ohm cold idle, and read 3 bar cold idle instead of normal 5 bar. When car was fully warmed it was reading 3 bar when driving, and around 1 bar idle. The data sheet I have for the sensor says resistance should range from 10 to 184 ohm. The NOS sensor was dated 2009.
The Porsche-sourced sensor dated June 2020. Static resistance is 9 ohm so I'm pretty sure the gauge will now read correctly after it's installed.
When the engine is cold the gauge "pegs", i.e. it is full scale deflection. All this tells you is that the pressure is higher than or equal to 5 barg and that is perfectly healthy of course. When the motor is fully warmed up my gauge displays as 2 barg. The sender creates a specific resistance value and the dash panel gauge interpolates that to give an output. Perhaps of just as much interest would be the pressure value the switch changes over at. I reckon that is likely to be 1 barg or 15 psig in round terms.
Moral of this story- if you are going to go cheap purchase a 2 pin generic sender for $25!
08-19-2021, 01:59 PM
#20
Drifting
Thread Starter
A 2-pin would work fine for the gauge, but I suppose I’d then lose the low pressure warning light?
I realise there are better things to spend 928 money on than a more accurate 3-pin sender, but I still find it reassuring to see a hot idle reading drop to around 3 bar in middle of arc. It was slightly alarming to see it drop to near bottom of gauge, even knowing the actual pressures are healthy!
I realise there are better things to spend 928 money on than a more accurate 3-pin sender, but I still find it reassuring to see a hot idle reading drop to around 3 bar in middle of arc. It was slightly alarming to see it drop to near bottom of gauge, even knowing the actual pressures are healthy!
08-19-2021, 02:05 PM
#21
Rennlist Member
A 2-pin would work fine for the gauge, but I suppose I’d then lose the low pressure warning light?
I realise there are better things to spend 928 money on than a more accurate 3-pin sender, but I still find it reassuring to see a hot idle reading drop to around 3 bar in middle of arc. It was slightly alarming to see it drop to near bottom of gauge, even knowing the actual pressures are healthy!
I realise there are better things to spend 928 money on than a more accurate 3-pin sender, but I still find it reassuring to see a hot idle reading drop to around 3 bar in middle of arc. It was slightly alarming to see it drop to near bottom of gauge, even knowing the actual pressures are healthy!
08-19-2021, 02:56 PM
#22
Drifting
Thread Starter
08-19-2021, 03:05 PM
#23
Rennlist Member
One can only presume they had some issue with a false earth or water splash corrupting the signal. In my case I could not get the correct Factory sender working so tried the cheapo approach as a last recourse as it were given those senders were used on plenty of different models [thus generic the copies]. My main concern was not the accuracy of the reading but the mechanical integrity. The unit I installed has been in service around 5 or 6 years now and no issues to date but I would have felt more comfortable with a pukka VDO unit on board.