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Old 09-09-2012, 08:20 AM   #1
Sophia69IS
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Exclamation High Idle, she won't come down.

Hey folks,

I decided to write a new thread because I was unable to find what I was looking for on the other threads in this forum.

As the title suggests, my car is idling high and she won't come down, here are some facts to help weed things out.

I have just recently completed "the mess under the intake" after one of my heater coolant lines burst, I have replaced almost every coolant hose, everything has been put back together, as of right now, there isn't any air left in the coolant lines as I have bled it all out.

The Problem:

When the engine starts cold (starts fine, no problems) it idles a little low but then levels off and starts idling at the correct RPM's, a little below 1K, after a few minutes when the engine starts to heat up, the RPM's steadly rise and then stay around 1200RPM's and 1500RPM's I have no idea why it's idling so high.

I have checked all vacuum hoses for a possible leak, everything is secure, I have rechecked my ICV, looks good, the idle isn't fluctuating, it is just steady at a high RPM, NOTE: I did change the position of the ICV slightly.

I don't really have any ideas other than a vacuum leak which I have checked and re-checked for, everything seems to be hooked up correctly and she starts right up then starts idling high.

Any advice on this would be very much appreciated as this is my DD, and would like to get her back on the road this weekend.

Thanks so much for your help in advance!

Cheers!

Sophia from Seattle
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Old 09-09-2012, 10:46 AM   #2
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idle won't start surging (up/down/up/down) until it gets over 1450 RPM (hits decel fuel cut)

Most high idle problems are caused by a vacuum leak, but if yours starts normal, then gets higher and higher, I expect that you're running a little bit rich as a baseline, then gets closer to stoichiometric as ECT rises. That may be another problem for another day.

Start by spraying Brakekleen around the intake manifold and hoses with the engine running. DO NOT spray near the exhaust manifold or plug wires unless you have a fire extinguisher handy. If you spray one spot, and the idle RPM jumps up for a second, you have a vacuum leak.

If you can't find a vacuum leak, check the signal voltage from the O2 sensor. If it stays near 0 volts, it's lean. Near 1 volt, it's rich. You should see it oscillating from .1 to .9 volts in normal conditions.
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Old 09-14-2012, 10:54 PM   #3
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For me it sounds like non-functioning ICV with incorrect setting of the throttle plate or/and TPS. Try the easiest thing: disconnect the ICV and see what happanes. Another thing: when you are driving at some gear (above 1500RPM) and lift your foot off the throttle what's the indication of the fuel consumption gauge?
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Old 09-28-2012, 04:15 PM   #4
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Thanks for everyone's replies, sorry it took me awhile to update, I have been really busy and biking to work since this car is my DD.

I have gotten new vacuum lines and tried the brake kleen thing, AlienBlood suggested, I couldn't find any leaks.

I tried the stomp test to see if the computer recognized any problems, it doesn't.

I took the intake off and checked to make sure I had hooked up everything correctly, I have, and I also replaced the fuel injector temp sensor as suggested to me by the good fellas at m42club.com

I have just put it back together and the same result, no difference.

Petrolhead, if I take the ICV and unplug it the idle starts to fluctuate irratically, so I believe it is working. The idle stays pretty constant, it just climbs higher and higher.

Alienblood, I don't have a means to rest the resistance of my O2 sensor at the time, you think that could be it?
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Old 09-28-2012, 04:22 PM   #5
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I may be wrong but if the ICV is unplugged the ECU automatically goes into fail mode. Sounds like your ICV is not adjusting for the high temps. Try cleaning it. Also reset your ECU by unplugging battery for a minute
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Old 09-29-2012, 08:08 AM   #6
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I'm not sure about the ICV and the ECU and automatic fail mode, but I have cleaned my ICV and reset my ECU twice now, doesn't seem to be helping. =(
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Old 01-10-2015, 10:32 PM   #7
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Did you fix it??? I have the same problem
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Old 01-11-2015, 05:38 AM   #8
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First check the blue temp sender on your thermostat housing. Sometimes the plug gets a dry joint and won't read right. Get back to us. We'll sort it for you.
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Old 02-04-2015, 01:23 PM   #9
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My 89 ix has a high idle at about 1700. It never comes down even when at running temp. I played around with some of the sensors. I unplug the MAF and the idle drops to normal but the car is un-driveable. Unplug the o2 and nothing changes. Unplug the ICV and the idle stays stable at 1400.

Ill try the brake cleaner thing when I get home but I thought brake cleaner would dry rot rubber. I know carb cleaner will melt rubber. I guess starting spray would be to volatile.

I will also check the temp sensors when I get home today.

How do you measure the signal for the o2? is there a pin-out someplace you can get to?

Thanks
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