Idle issue & sensor in radiator

[jumpshotjonny]

So have two issues:

1) A couple of times the idle RPM have jumped up to 2k RPM after letting off of the accelerator and then if I push the accelerator and let go it will go back to the normal idle RPM.

I noticed that on the throttle assembly there is a white plastic piece that is broken.

Here's a picture:



Could this perhaps cause something like my symptoms?

2) The sensor that is plugged into the radiator on the passenger side is not connected to anything. Looks like the wire for the connector was cut or something. What is this supposed to be wired to? And what is this sensor for? Does the gauge on the dash use this?

Picture:



Apologies for any dumb questions I'm new to E30s.

[101]

1) Yes, that could definitely be your problem. From the picture the boot that covers the exposed throttle cable is also in three parts. I'd bet the cable is sticking in the housing causing the symptoms you describe. Disassemble, replace the broken parts and spray some white lithium grease down the housing. and work the cable back and forth to ensure smooth operation. If it still seems like it is sticking in the housing, replace it. There is nothing more exciting than a throttle cable that sticks when you least expect it!


2) The switch on the side of the radiator controls the operation of the front electric auxiliary fan. I can't tell from the picture exactly what is cut and where it is cut. There are also some A/C pressure switches in that location that may have been taken out if your car no longer has the A/C installed. The sensor that operates the dash gauge is on the thermostat housing.

[jumpshotjonny]

Awesome, thanks!

I'll try to trace the wiring from the aux fan and see if I can figure out where that is supposed to be connected. And I've got the bentley manual so maybe it explains the wiring somewhere in there.

[Kozworth]

1). Id try removing that whole throttle cable and rev at the tb, and see if the stick still happens. Try wiggling the wires for the iac, a buddy of mine had a intermittent idle issue where it would rev up and down, and turns out the wires weren't secure in the iac harness.

2) 101 nailed it.