IS nthere Prob with Air Intake Temp & O2 Values?

[dan]

Hi guys Its me again 🙂
I’m using a Honda Civic vtec 1.6L (ES5) i had few problems with this car, so let me quickly explain what happened.
>had a Problem with random over heating (after driving 50-60km car started to over heat)
>found out secondary o2 sensor was faulty , but ran with that faulty sensor for about 6-7 months knowing that there will be a impact on my gas cost)(other than Check Engine light there was no problem)

> then car used to stall in the morning when I’m starting for the first time of the day
(during that time I had to charge spark plugs regularly )

______________________

Then found out its the head gasket and changed it.
Wow everything is ok. no over heating issues.

but sometimes car rpm drops (when @ idle ) ( 800 to 650 ) and i feel a bit of a vibration

also car got stall when taking a Full turn (then said my power steering belt was too tight and he adjusted it)

so I plugged a bluetooth obd2 and used the car for few hours and recorded all the data.

I have attached a pic of some screen shots.
I have 2 Questions

1) Is my Air Intake temp is too high? (see the picture)

2) something wrong with my 02 sensors ? (I replaced the Secondary O2 sensor recently and i got it from ebay not a original Honda sensor

o2 Primary voltage is not stable at all (changes ~0.8V to ~0.01V)
Is that normal ?(see the picture)

http://i44.tinypic.com/2rdyds0.jpg

Topic

[dan]

Hi guys Its me again 🙂
I’m using a Honda Civic vtec 1.6L (ES5) i had few problems with this car, so let me quickly explain what happened.
>had a Problem with random over heating (after driving 50-60km car started to over heat)
>found out secondary o2 sensor was faulty , but ran with that faulty sensor for about 6-7 months knowing that there will be a impact on my gas cost)(other than Check Engine light there was no problem)

> then car used to stall in the morning when I’m starting for the first time of the day
(during that time I had to charge spark plugs regularly )

______________________

Then found out its the head gasket and changed it.
Wow everything is ok. no over heating issues.

but sometimes car rpm drops (when @ idle ) ( 800 to 650 ) and i feel a bit of a vibration

also car got stall when taking a Full turn (then said my power steering belt was too tight and he adjusted it)

so I plugged a bluetooth obd2 and used the car for few hours and recorded all the data.

I have attached a pic of some screen shots.
I have 2 Questions

[color=#880044]1) Is my Air Intake temp is too high? (see the picture)

2) something wrong with my 02 sensors ? (I replaced the Secondary O2 sensor recently and i got it from ebay not a original Honda sensor

o2 Primary voltage is not stable at all (changes ~0.8V to ~0.01V)
Is that normal ?(see the picture)
[/color]
http://i44.tinypic.com/2rdyds0.jpg

[dan]

Also I haven’t done a proper ECU rest after that(head gasket replacement), other than removing the fuse and putting back.

Is there proper a way to reset the ECU ??

Thanks
Kp

[Kevin Criswell]

An IAT reading should only be + or – 10 F of ambient temperature

A reading of almost 150 is WAY too high in either Celsius (300 F) or Fahrenheit

Time to test the IAT sensor.

First thing to do is get a reading from the car stone cold. Let it sit all night, go out plug in the tester, turn key on (do not start car) and get a IAT reading it should almost equal the ECT reading perfectly.

BTW you had a head gasket problem, replace your upstream O2 sensor even if it appears to be okay. Phosphates and Silicates WILL contaminate and ruin the Zirconia lattice that makes up the thimble. Over time the Zirconia will no longer react with oxygen ions and start to loose their voltage output leading to a lazy and ineffective O2 sensor.

[Its me]

Unless your ambient air temperature is greater than 100+ then this is probably off. The air intake temperature is an important piece of data for the car to run properly and get the most fuel efficiency… If improper, you can have a rough running engine…

The O2 sensor is acting as it should, it should constantly run between rich and lean, and the computer makes minute adjustments… If it is a rear O2, it should somewhat stabilize after the cat has reached light off temperature…

-Karl

[Kevin Criswell]

Your IAT is a two wire NTC sensor (meaning as temperature increases, resistance will decrease) One wire is ground and the other is the signal sent (the computer sends 5 volts through a resistor and than out to the sensor. The computer watches the voltage drop on the signal line and determines temperature based on the voltage drop.

You can unplug the IAT and ohm it, at 32 F the resistance should be about 9,400 ohms, at 50 F it should be about 5,700 ohms, at 68 F it should be about 3,500 ohms and so on. You should have 5 volts (with sensor unplugged) on one wire (key on engine off) and a good ground on the other.

I test them like this.

Unplug and ohm sensor and compare to chart
Test for 5 volts on signal wire (key on engine off)
plug sensor back in (if it passes the ohm test and I have 5 volts)
back probe the 5 volt wire, test with voltmeter, I should see between 3.5 volts and 4 volts (depends on temperature) you are looking for a voltage drop.
Place positive DVOM meter lead on the ground wire (backprobe, still pluged in and key still on engine off) and negative on battery ground, you should see less than 200 millivolts of voltage drop.

[Kevin Criswell]

As to your, what is normal for oxygen sensor question

[dan]

“get a IAT reading it should almost equal the ECT reading perfectly.”
what is ECT ?pls explain

[dan]

Thanks
What is ECT ?

saw your O2 sensor video , according to that quick lean – rich change is normal.
But but secondary o2 sensor doesn’t change that much,(one i bought from ebay)

is it a faulty sensor?

Thanks
Kp

[dan]

Hi i just checked the Air intake Temp again. it was around 85-90 (car was switch off for more than 12 hrs frm its last start) I think its in Fahrenheit here normal ambient temp is 30C (86F)

so u think 150 F (65 C) is too high?
Thanks
Kp

[dan]

Oh thanks Karl
then my both o2 sensors acting how it should.woow 😀
but 60-65 C air intake temp is too high??

Kp

[Kevin Criswell]

ECT stands for Engine Coolant temperature (sorry, I forgot to explain that acronym)

Yes the secondary O2 (behind the converter) should NOT switch back and forth, it should be almost a flat line with small variations. This is due to the converter doing it’s job and stabilizing and converting the gasses in the exhaust stream.

150 F is way to high.

It sounds like the sensor is going bad and shorting out as the the temperature rises. A NTC sensor (negative temperature coefficient) sensor goes down in resistance as the temperature goes up. I have seen them fail at a high temp and still be good at a low temp. Since that sensor records the temperature of the air moving through the intake from outside the vehicle it’s reading should only be about 10 degrees higher than the temperature outside. If it’s 86 F outside the IAT reading should be about 96 F. A abnormally high reading will cause the ECM to drastically change the fuel mapping and can cause significant running issues.

BTW verify your reading by doing the tests, your code reader might be lying to you and nothing is wrong (it happens).

If you have a voltmeter still do the tests I outlined, the job now is to prove that the sensor is bad.

[dan]

Hi Thanks.
my ambient temp is around 86-90F when car is cold(switched off overnight) Air intake temp matches that. but after driving about 20-30 mints its goes up to 130-150 mark,
so when the car engine is hot intake air should be hot(130-150F) bcos if it,s getting air from air intake (through air filter ) it should be hot anyway bcos engine heat. correct me if I’m wrong

KP

[Kevin Criswell]

[quote=”Kp” post=80619]Hi Thanks.
my ambient temp is around 86-90F when car is cold(switched off overnight) Air intake temp matches that. but after driving about 20-30 mints its goes up to 130-150 mark,
so when the car engine is hot intake air should be hot(130-150F) bcos if it,s getting air from air intake (through air filter ) it should be hot anyway bcos engine heat. correct me if I’m wrong

KP[/quote]

Not really, air ducting brings the air in from outside the vehicle’s engine compartment. Like my S-10 draws air in from behind the driver’s headlamp assembly. The air is moving to fast to gather much heat (reason your temp should only be about 10 degrees hotter) from the engine compartment. The only time the IAT should show high heat levels is during a “heat soak” (after you shut the engine off and heat bleeds to all parts of the engine and compartment).

[dan]

I tried with another app.its showing a lower air intake value now (earlier it was 150F/65C)
now with this new application its around 122F/50C (my ambient temp is around 90F/32C)

Kp

[Kevin Criswell]

[quote=”Kp” post=80628]I tried with another app.its showing a lower air intake value now (earlier it was 150F/65C)
now with this new application its around 122F/50C (my ambient temp is around 90F/32C)

Kp[/quote]

Sounds like a problem with the app’s software and your sensor is most likely okay.

[Author]

Replies