96 Saturn SL2

[goldsmith]

I fix my own stuff whenever possible which is fairly frequent. i finally got to build myself a nice little workshop that has 2 bays and a dug out work pit that covers with a sheet of 3/4" plywood. i like fixing cars so i get to do it for the extended family typically. some days lucky, some days are discouraging- but it all works out somehow through patience and perseverance.
the problem today is my daughters Saturn that is a dohc with a 5 speed manual. it has been running pukey and rich. the plugs were all sooty and it wanted to die whenever taking off from a stop. it stumbled and died unless it was gingerly revved up before letting the clutch out. we put new hotter plugs in and some lucas fuel cleaner and it is much better- almost normal, but the service engine light came on and the autozone scanner said "P0113 IAT Sensor1 Circuit High Input". a website list says that means "intake air temperature sensor circuit high voltage". the autozone guy said he never heard of that and they don't sell a replacement part for it. so, we don't know what to do about it or what it means.

[re-tired]

Welcome to the forum. Sorry we did not get to you right away but the fish were biting like crazy.At least thats my excuse.The IAT can cause the symptoms your having ,it tells the computer the temp of the incoming air so it can adjust the fuel ratio . I dont have the diagnostic flow charts in front of me but one of my partners in crime will chime in shortly. You may have to get that part at dealer if it test bad.

[DanD]

Hi and welcome to the board.
The test procedure I have for this involves using scan data and watching the output temperature readings of the sensor as the under hood temperature changes or when the sensor is disconnected compared to being jumpered across the connector. Open connection –35 jumpered 260 degree
You not having a scanner you might be able to use the coolant temperature sensor as a comparison of the resistance reading.
Both sensors work in the same way, that when they are cold the resistance value of the sensors is high, the computer uses this voltage drop across the sensor to interpret temperature.
So if the car is left overnight and not started both the coolant sensor and the air temperature sensors resistance value should be very close to being the same. Take the reading across the two terminals of each sensor while it is disconnected.
If they are relatively close then start looking for a bad connection or open in the wiring harness going to the computer. Sorry there is a resistance verses temperature chart but I can’t seem to find it right now.
Have a close look at the terminals inside the connector sometimes they will spread apart and not make a good connection even though the connector itself plugs in fine.
Dan.

[re-tired]

Is that a Simpson 260 meter Dan ? At least you can draw better than me. ;D ;D

[DanD]

Ok I was a little hungover and when I drew what I thought was a square box, looking at it again I must have had the shakes a lot worse then I thought and no it’s not Simpson 260 it’s a snap-on can’t you see it’s red. LOL
Dan.

[goldsmith]

Thank you, your information is clear and i am encouraged that I can get the part tested as soon as i find it. i see from the haynes manual that it is in the air intake somewhere. At first perusal i didn't see anything hooked up to the air intake that looks like this but it must be there somewhere. i hope the thing flunks the test and i can simply replace it and the kids will be back in business.

[DanD]

I hope I didn’t mislead you with the picture of the Bosch sensor, I only used it as an example as to where to connect the ohmmeter.
Your sensor won’t look the same as it does, but it would accept the connector that is shown.
Here’s a better example of what it’ll look like, it may not have the threaded portion.

According to my component locator it agrees with yours, that it is in the air intake duct, so look anywhere from the air cleaner to the throttle plates.
Here’s the resistance chart I couldn’t find earlier.

[goldsmith]

Success- mostly. i took the air duct off from above the rad, looking for this ethereal animal called the Intake Air Sensor. Sure enough, it is the little bulb inside and just before the air cleaner. Dark like the duct itself and no bigger than the end of a #2 pencil. it was unplugged just like we probably left it the last time we were in there. i plugged it back and the car is much better. it still starts hard- needs full throttle no pumping to get the mixture balanced, then wants to die for about a minute- still too rich. After it warms up it acts normal- except that every so often it still tries to die when leaving a red light. there is still something up but it is way better with the IAT sensor plugged in. i think i'll keep it connected this time. maybe even do the resistance test after all.

[goldsmith]

Though much better the car still intermittantly stumbles. It is a little hard to start but always will with full static throttle. Lays a little blue cloud each time it starts from cold. It tries to die when idling during the first minute or so, then drives normally most of the time. Occasionally, and without warning even after warmed up, it will stumble when revving to take off from a stop. During the times that it is showing this symptom, it can be revved up with the right touch on the accelerator, but cuts out at 4K or so rpms and then catches again. After a tantrum like this it goes again like everthing is fine. I have now driven it enough to burn the fuel that had the Lucas fuel system cleaner in it. It is still just not quite acceptable to turn back over to my daughter. The engine light has stayed off since we reconnected the IAT sensor. What should we do next?