High idle October 04, 2013, 10:44:55 PM What things should I be checking? I know the basics... vacuum leak, bad tps, but what else? Quote Selected
High idle Reply #2 – October 04, 2013, 10:56:54 PM I have a TBI 5.0, pretty sure it doesn't have a IAC valve. Quote Selected
High idle Reply #3 – October 05, 2013, 12:27:13 AM All the time? Just hot? Whats up?Guessing coolant temp sensor, if no vacuum leaks. Does that car run codes? Quote Selected
High idle Reply #4 – October 05, 2013, 01:52:30 AM it's hard to say, but even after it's warmed up, no foot on the gas, it's going faster than it should. Quote Selected
High idle Reply #5 – October 05, 2013, 07:04:05 AM OK Idle air system/control/valve. No matter what type of induction system a car has it has a way to control idle speed. TBI has an idle bypass system. Been a very long time since i have worked on one but it is in the TBI assembly. And if the ECT sensor is bad or the engine coolant does not come up to temp that can cause it to! Quote Selected
High idle Reply #6 – October 05, 2013, 02:33:02 PM First you couldn't get on fast idle and now you can't get off of it. Bummer.Pull the air cleaner off so you can see what's going on.On the driver's side of the CFI, there is a vacuum dash pot. Pull the vacuum hose off and plug it. Now the ECU is out of the picture.The vacuum dash pot controls the idle after it is off the fast idle cam.Is the dash pot what's stopping the throttle linkage? If so it needs to be adjusted.If not the fast idle cam is controlling the idle. This is on the passenger side of the CFI.When you pump the gas pedal before you start, it moves to the highest of three fast idle steps on the cam.When you start and have vacuum, a vacuum pulldown moves the cam to the middle step.A electrically heated gizmo ( like an electric choke on a carb) moves the cam until it drops off the high idle steps.Check the wire to the gizmo for 7 to 8 volts with the engine running.Do you still have the stock 1G alternator? Quote Selected
High idle Reply #7 – October 05, 2013, 03:04:19 PM When I start it, it idles high, then after a few seconds it comes down, but I believe it should be coming down lower.So the fast idle is on the pass side by the TPS, and on the driver's side there's the plunger that pushes the throttle linkage open a little. I noted on the driver's side that the linkage is not resting on the stop, but the butterflies in the throttle body are completely closed. Quote Selected
High idle Reply #8 – October 05, 2013, 03:06:21 PM he should have the ISC motor control for idle... i know the cfi system your talking about soft touch and that was 80-83 only, eecIII systems.correct?anyhow, loosen up the **lock down screw** of idle speed motor control on the front driver side of the CFIonce you do this, there is a threaded rod adjustment to move the whole assembly forward and back.when you first turn the key forward only on a bone cold motor, you will see the plunger push out about 3/16'' because its positioned just right to barely open up the throttle plates for a cold engine.when the motor warms up,, the pluger retracts only if what tom said happens,,, the computer gets warm up conditioin signals.not a bad design in my opinion but it is rather fickle to adjust,, i never really mastered setting it perfectly,,, however if you fiddle with it a little, you'll start to see how it works and what to do and how to finally set it when the motor is warm.id have to look up the correct steps in the shop manual but here is how i use to set mine.-before starting it is very important the pluger on the ISC is fully retracted, even if you have to make it retract with correclty placed battery power directly into the connector.-warm up motor with the isc all the way backed off and you may have to help it run with a little bit of shimming on the CFI idle stop adjustment--take a peek below the trottle linkage and you will see what "causes" the CFI to have a stop on the linkage.-once warm, adjust the idle speeed motor all the way up to the throttle linkage paddle the isc bumps into.-just adjust it till it is giving you an acceptable idle speed then remove your temporary thingy you used to keep it running-let the motor cool down...-turn key forward and watch the plunger on the isc to see if it pops out a little bit.. if it doesnt, its not getting a signal or its broke.-if it does push the plunger out a tiny bit, start the car and it will idle high then in about 30 seconds you should see the plunger little by little start to retract and your idel should come down as well. Quote Selected
High idle Reply #9 – October 05, 2013, 03:09:18 PM Quote from: White85GS;422965When I start it, it idles high, then after a few seconds it comes down, but I believe it should be coming down lower.So the fast idle is on the pass side by the TPS, and on the driver's side there's the plunger that pushes the throttle linkage open a little. I noted on the driver's side that the linkage is not resting on the stop, but the butterflies in the throttle body are completely closed.its normal to have the stop screw not touching,, thats the way it is on all CFI's,, its a hair but still not touching.you should just need to back the idle speed motor down a little bit more,, you just need to fine tune it Quote Selected
High idle Reply #10 – October 05, 2013, 03:17:55 PM The ISC motor is only on the 3.8L. Quote Selected
High idle Reply #11 – October 05, 2013, 03:31:58 PM Quote from: White85GS;422965When I start it, it idles high, then after a few seconds it comes down, but I believe it should be coming down lower.So the fast idle is on the pass side by the TPS, and on the driver's side there's the plunger that pushes the throttle linkage open a little. I noted on the driver's side that the linkage is not resting on the stop, but the butterflies in the throttle body are completely closed.If the throttle plates are closed and can't go any farther, then you must have a vacuum leak.The plunger on the driver's side should be touching the linkage if it is off the fast idle cam on the other side. Quote Selected
High idle Reply #12 – October 05, 2013, 05:57:14 PM Some diagrams. Note, if you have upgraded the alternator, you probable cut the wire to the thermostat heater. Quote Selected
Topic: High idle (Read 3981 times)
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