Question on BMW 3-Series E36 Thermostat

Hello, I have a 1988 BMW 325i Convertible
I noticed when I turned on the car its temp gauge would jump from cold to hot with out even being on for all of five mins.

So what I did was I replaced the thermostat, however it still occurs so I ordered new coolant sensors and etc

But Im still unsure because it idles rough like a smokers cough before it never had any issues. So I'm wondering what it could be.Thanks.

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[Nick at Pelican Parts]

Sounds like you have an engine misfire. I would guess the coolant gauge issue is a separate issue.

I would start by checking the DME for fault codes. If the system is not working properly, a fault code will be set. This will be your best bet when diagnosing.


- Nick