Mystery knob under dashboard, 1989 Toyota Blizzard with 2L-T diesel

thevictor390

Teen Wankeler
Joined
Mar 9, 2007
Messages
11,892
Location
Massachusetts
Car(s)
'17 Mazda MX-5 RF, '89 Toyota Blizzard SX5
Hi guys, PYC coming soon as I just heard that the registration went through and will be picking up plates tomorrow, but I wanted to know if anyone has any idea what this knob is for:




It's just under the steering wheel and turns like a screw (tightens when turned clockwise and loosens when turned counter-clockwise). Turning left eventually just releases it to spin freely but it doesn't come off.

The only thing I can notice is that the engine seems change idle speed based on the position of the knob, with a slight delay. It goes from ~500rpm to ~1000rpm.

Is it intended for cold starts or something? Where should I leave it under normal driving? I am completely new to diesel and everyone I ask seems to have no idea :dunno:
 

RdKetchup

Snow Mexican Surender Monkey
DONOR
Joined
Feb 18, 2007
Messages
4,816
Location
Montreal, Qc, Canada
Car(s)
FoRS, Japanese touring triple
This looks like an actual choke knob, not an idle adjustment knob. I'm guessing you have a carburetor?
 

thevictor390

Teen Wankeler
Joined
Mar 9, 2007
Messages
11,892
Location
Massachusetts
Car(s)
'17 Mazda MX-5 RF, '89 Toyota Blizzard SX5
This looks like an actual choke knob, not an idle adjustment knob. I'm guessing you have a carburetor?
I'll be the first to admit virtually zero mechanical knowledge, but this seems to indicate that all diesel engines are fuel injected:

http://en.wikipedia.org/wiki/Fuel_injection

That is indeed an idle adjustment knob... never had one myself though :dunno: afaik it's for increasing the idle speed for a cold start if the engine is too shaky otherwise, and speeds up the warming.

http://www.pointedthree.com/disc/forums/showthread.php?tid=7576&start=1
This is what I suspected but wanted to be sure before driving around with it on the wrong setting!
 
Last edited:

BerserkerCatSplat

Hormone Induced
Joined
Jun 21, 2005
Messages
9,633
Location
Alberta, Canada
Car(s)
The Jeep of Theseus, Angry Wagon
Yep, it's an idle control knob. Diesels tend to be pretty iffy in the cold at low RPMs so while some vehicles will automagically run a high idle at low ambient temps, others have a manual controller instead.
 
Top