Idle stuck around 2000 rpm - Toyota Nation Forum : Toyota Car and Truck Forums

wambus · 04-09-2008, 11:10 AM

Where should I start looking to get my 87 NA Supra to idle correctly. I understand that about 500 rpm is normal, so I am way over that. I am also experiencing a rattle in the engine (that I am discussing in another thread) that seems to be tied to the isdle speed somehow. I would like to try and conserve a little fuel with gas prices where they are and I imagine that this high idle is not good for the engine. I have a multi tester and a trashed factory shop manual.

Jeeves · 04-09-2008, 04:25 PM

When cold or warm?

wambus · 04-09-2008, 11:34 PM

When I start it up it was automatically going to 2100, then it might come down to 1900. Now it tends to start out at around 1500 and as it is driven it bumps up to around 1900. The rattle/noise I am hearing does not occur when it is idling around 1500 - even if I rev the engine. As the idle rpm moves up to 1900 or better the noise appears....

Jeeves · 04-10-2008, 01:48 PM

I had a similar problem when I managed to break wires going to the idle speed controller. Might wanna check them out. Also might wanna check that your throttle linkage isn't too tight and holding open the throttle.

CRE · 04-13-2008, 02:31 AM

Start with checking that the dash pot isn't stuck or clogged.

http://www.cygnusx1.net/Supra/Librar...Section=EC&P=8

It's supposed to slow the throttle plate when you let off the gas. When you set it you open the throttle, plug the dash pot's breather, release the throttle and adjust the dash pot's plunger until the engine is sitting at 2000RPM.

wambus · 04-13-2008, 10:06 PM

The problem appears to be related to the valve that lets air travel to or from the plenum from/to the intake - the one with the coolant line going to it. I took it apart and found no visible issues. I have not had time to check the temp sensors/switches. I took off the connecting line and plugged both openings . Car runs fine once it is warmed up.. Still other issues though.