P0113 on 2001 Honda Accord / non-drivable…

[Uncle Ben]

Hi everyone. I seem to have gotten myself into trouble. I have a 2001 Accord with 135k miles, 4cyl, and I was trying to solve some idle issues by remvoving the intake and cleaning the throttle plate and bore, and cleaning the idle air control valve (IAC).

After putting it all back together and starting up the car…there is a huge problem. Not only is the engine not running better, it is far worse, to the point of being un-drivable.

As soon as he engine is started up, it revs up in a continual pulsing pattern. It revs up high (about 4,000 rpm) and then goes back down every 1 or 2 seconds, and it will keep doing it for as long as I leave it running. It is also making some type of whining noise along with the engine revving that I have neve heard before.

Due to the IAC being right against the firewall, and the mounting bolts facing the firewall, I had to remove the air intake and all the various vacuum hoses and electrical connectors, but I labeled them first to make sure I put them all back in the correct place, and I have checked many times to see if there was anything I forgot to connect or connected to the wrong place, but I can’t see any issues.

My scanner is showing P0113, “Intake Air Temperature Sensor 1 Circuit High”

Freeze frame data says the intake air temp was -40 (I live in CA and it wsa over 50 at the time, far from a negative temperature. Engine coolant temp 71. Fuel system status says “Open loop due to insufficient engine temperature”.

I tested the ITC (intake temperature sensor) and I’m getting the following readings, which seem to be correct, but please let me know if I am interpreting the ohms incorrectly (I sometimes confuse ohm readings on the multimeter)…
on the 200k scale: 003
on the 20k scale: 2.5
My repair manual says resistance should be 2,500 to 3,500 ohms with the connector removed and the engine off.

I also removed the ITC and bench-tested it according to the manuel, which says to heat the sensor with a heat gun and that the ohms should lower to about 250 ohms at 180 degrees f. I don’t know how quickly I reached 180 degrees, but I do know that the ohms dropped quickly as the heat gun got warmed up, which I’m sure was well beyond 180 degrees, and the ohms continued to drop below 250 (I tried not to get the heat too close or heat it for too long). To me it would appear that the sensor is fine, but then why would I get P0113 code?

Thanks for your advice!

Topic

[college man]

reading -40 either the wiring has a problem or
the sensor does.do you read voltage to the sensor?
if the voltage to the sensor checks out.replace the
sensor.

[Uncle Ben]

I should have taken better notes as I was checking things after this problem started. If I remember correctly, there was voltage to the intake temp sensor, but I’ll check it again. If there is not voltage to the intake temp sensor, would that mean an issue with the PCM? Maybe a blown fuse?

[college man]

if there is no voltage check fuses and wiring.

[Uncle Ben]

Now I’m even more confused by the P0113 trouble code related to the intake temperature sensor. There is voltage going to that sensor, and the sensor itself seems to be in working order after bench test.

[Uncle Ben]

FIXED! It was a vacuum leak at the back of the plenum, against the firewall. A metal hose supporting bracket was pinched between the plenum and the intake when I bolted it back together. I found it by doing a smoke test. I had no idea a vacuum leak could cause idle issues that severe, to the point of being non-drivable. No more check engine light or trouble code either.

Driving the car to work today I could see that the original idle issue that prompted me to clean the throttle body and the idle air control valave is now gone. It is idling at about 750rpm, right where it should be.

[college man]

Glad you found the issue.vacuum leaks can cause
idle problems, excessive fuel use, o2 problems.

[Author]

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