Blue temp sensor

Need technical Q/A then you're in the right place

Moderator: martauto

User avatar
Rhyse30
E30 Zone Newbie
E30 Zone Newbie
Posts: 160
Joined: Sun Mar 03, 2013 11:00 pm
Location: Cardiff

Post Mon Jan 12, 2015 12:05 pm

Working on my engine yesterday (m20b25) as I'm still having starting and idle problems. Was unable to disconnect the blue temp plug as the fuel rail/that bar that clips on to the injectors was in the way. Realised the blue temp sensor was not screwed in properly and sticking out about 10mm!

Checked the resistance it at the ECU and at the sensor itself with a multimeter and it was showing 4300 ohm when cold. I then screwed it in properly and it went to 4200 ohm when cold.

The wiki states between 3500-4000 but any more or less isn't a huge issue? Would 4300 make much difference?

My engine seemed to run a bit better this morning with the sensor screwed all the way in. Still not perfect. Would the 200 ohm over be the problem?

Thanks
Grrrmachine
E30 Zone Wiki / Team Member
E30 Zone Wiki / Team Member
Posts: 8043
Joined: Sat Feb 09, 2008 11:00 pm
Location: Warsaw, Poland

Post Mon Jan 12, 2015 12:21 pm

200 Ohms won't make a huge difference; it's the resistance between hot and cold that really matters. Did you take a hot reading too?
User avatar
Rhyse30
E30 Zone Newbie
E30 Zone Newbie
Posts: 160
Joined: Sun Mar 03, 2013 11:00 pm
Location: Cardiff

Post Mon Jan 12, 2015 12:29 pm

Yes, the hot reading was 310 ohms at the ECU. So this probably isn't the cause of my issues...or at least some of them?
Grrrmachine
E30 Zone Wiki / Team Member
E30 Zone Wiki / Team Member
Posts: 8043
Joined: Sat Feb 09, 2008 11:00 pm
Location: Warsaw, Poland

Post Mon Jan 12, 2015 12:33 pm

No, those readings sound find to me. So the issue is either an air leak or dribbly injectors, or a combination of both.
User avatar
Rhyse30
E30 Zone Newbie
E30 Zone Newbie
Posts: 160
Joined: Sun Mar 03, 2013 11:00 pm
Location: Cardiff

Post Mon Jan 12, 2015 12:43 pm

The only place I haven't properly checked for air leaks yet is the inlet manifold gasket. Need to send my injectors to injectortune soon. Car is currently my daily driver so can't take the injectors out. I might as well replace the manifold gasket while I'm doing the injectors.

Thanks for the help again! Hopefully/finally get this sorted asap!
capri_rob
Married to the E30 Zone
Married to the E30 Zone
Posts: 9678
Joined: Tue Feb 19, 2008 11:00 pm
Location: South Staffordshire

Post Mon Jan 12, 2015 1:31 pm

Check and set your valve clearances properly and make sure the rocker cover is properly bolted down.

I chased air leaks and idle issues for months before determining it was down to incorrect valve clearances
Image

e30topless said : Proper BMW's have 4 headlights, last of the run was the E30 and E34/E32 anything after that is just complete shite
User avatar
Rhyse30
E30 Zone Newbie
E30 Zone Newbie
Posts: 160
Joined: Sun Mar 03, 2013 11:00 pm
Location: Cardiff

Post Mon Jan 12, 2015 7:00 pm

Ah right ok. Thanks Rob ! Didn 't really think about valve clearances ! Havn 't done them in around 2 years ! Havn 't replaced the valve cover gasket since I put the engine in. I know what I'll be doing all weekend then!