High constant idle - 1990 Integra GS
02-22-2014, 03:03 PM
#1
Honda-Tech Member
Thread Starter
High constant idle - 1990 Integra GS
Problem: At first startup, the car idles at about 1,700, then climbs to around 2,000 rpms as the engine temp increases.
I think I have ruled out a vacuum leak by disconnecting the breather and placing my hand over the throttle body, and then the engine promptly dies.
The coolant was bled, according to the manual. The sensors are all new, and the dashboard temp sensor appears to be working, as is the fan temp switch and the thermostat. I have swapped the ECT sensor back to the prior one used before the rebuild, and no change.
Both the IACV and FITV were cleaned. I adjusted the FITV just to be sure.
If I disconnect the IACV connector, the engine idles around 800 to 900 +/-. This lead me down the path of the issue being related to the ECT sensor. The wires actually snapped off the plug under inspection, so I had to rewire/repin the plug. After this, I tested the voltage and I am getting about 4.9 between the Red and Ground, or the Red and Green wires, so what the ECU is sending at least appears to be fine.
Also tried another ECU, and the problem did not change, although the integrity of the alternate ECU is in question (ebay: Code 13).
More things to consider:
Swapped from Auto to Manual transmission, and still using the Auto ECU. The starter wire and the gear selector wire are in "park", and I am able to remove the key.
Still using an Auto Intake manifold. Air boost valve remove and holes plugged.
EGR valve and control unit removed. Vacuum lines plugged. EGR valve cover plate installed with seal.
ABS removed and swapped to a 40/40 valve (abs light is on, if that matters).
Swapped from power to manual steering rack.
AC pump removed.
No CEL codes, until I drive for a little bit and the EGR trouble code comes on.
************************
I think that covers the details. At this point, I think either something to do with the Transmission, EGR, PS, or ABS conversion (I know, too much at once) is the cause, or maybe a bad IACV. A bad IACV doesn't make sense to me, since unplugged, the issue goes away.
What am I forgetting? Why has this ECU forsaken me?
I think I have ruled out a vacuum leak by disconnecting the breather and placing my hand over the throttle body, and then the engine promptly dies.
The coolant was bled, according to the manual. The sensors are all new, and the dashboard temp sensor appears to be working, as is the fan temp switch and the thermostat. I have swapped the ECT sensor back to the prior one used before the rebuild, and no change.
Both the IACV and FITV were cleaned. I adjusted the FITV just to be sure.
If I disconnect the IACV connector, the engine idles around 800 to 900 +/-. This lead me down the path of the issue being related to the ECT sensor. The wires actually snapped off the plug under inspection, so I had to rewire/repin the plug. After this, I tested the voltage and I am getting about 4.9 between the Red and Ground, or the Red and Green wires, so what the ECU is sending at least appears to be fine.
Also tried another ECU, and the problem did not change, although the integrity of the alternate ECU is in question (ebay: Code 13).
More things to consider:
Swapped from Auto to Manual transmission, and still using the Auto ECU. The starter wire and the gear selector wire are in "park", and I am able to remove the key.
Still using an Auto Intake manifold. Air boost valve remove and holes plugged.
EGR valve and control unit removed. Vacuum lines plugged. EGR valve cover plate installed with seal.
ABS removed and swapped to a 40/40 valve (abs light is on, if that matters).
Swapped from power to manual steering rack.
AC pump removed.
No CEL codes, until I drive for a little bit and the EGR trouble code comes on.
************************
I think that covers the details. At this point, I think either something to do with the Transmission, EGR, PS, or ABS conversion (I know, too much at once) is the cause, or maybe a bad IACV. A bad IACV doesn't make sense to me, since unplugged, the issue goes away.
What am I forgetting? Why has this ECU forsaken me?
Last edited by Prof007; 02-22-2014 at 04:42 PM. Reason: Spelling
02-24-2014, 09:13 AM
#2
Honda-Tech Member
Thread Starter
Re: High constant idle - 1990 Integra GS
I have a brand new OEM ECT sensor on order, hoping the issue is just a bad old ECT sensor and a faulty aftermarket replacement sensor. We'll see....
03-16-2014, 12:50 PM
#3
Honda-Tech Member
Thread Starter
Re: High constant idle - 1990 Integra GS
Replaced the ECT with a brand new OEM sensor. Nogo 
I was able to drive the car for over 50 miles today, but unfortunately the idle issue is still there. After the car does warm to running temperature, I am able to turn the car off an then back on. It starts to idle around 1,000, but climbs back up to 1,500 or 2,000 after a few seconds.
Anyone?
I was able to drive the car for over 50 miles today, but unfortunately the idle issue is still there. After the car does warm to running temperature, I am able to turn the car off an then back on. It starts to idle around 1,000, but climbs back up to 1,500 or 2,000 after a few seconds.
Anyone?
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