Intake Air Temp resistor experiment.

[repete86]

Originally Posted by cfg83

repete86 -



Check this out :

Where is __________? (on 4th Gen Honda Accords)
http://www.mycb7.com/bb/viewtopic.php?t=53


This "mycb7" website is dedicated to your Honda Accord, so I think this will be a place that you troll for all the grimey details of your 4th gen Accord.

CarloSW2

Nice. Thanks alot.

[LxMike]

Originally Posted by cfg83

LxMike -



There are already "dialing" performance mod chips on ebay. But maybe they only cover the "performance" end of the spectrum, or are (cheapy) audio pots.

Hrrrrmmmm, maybe I'll get one and perform an autopsy .

EDIT : Here's one on ebay for $30 !!!!!!
88-95-96-97-98 99-04-05-06 Saturn SC/SL/SW Chip Module
http://cgi.ebay.com/ebaymotors/88-95...QQcmdZViewItem

EDIT : Oh, brain fart on my part. Nowwwww I see the J/K.

CarloSW2

AFAIK those "performance chips" on ebay are nothing more than a resistor all dressed up to make it look like it's more than it is. you notice they have one for EVERY car out there.

[repete86]

Okay, I installed the resistor. I had some major problems, and my mileage plummeted. The car wouldn't shift lower than 3k rpm, and my check engine light is now on. I'm going to take a closer look at it tomorrow to see if I can fix it. I used a 1/2 watt 150 ohm resistor. It looks like on the cable that connects to the IAT sensor, there are three connections. One is the ground, and maybe I ran the resistor into the wrong holes, or maybe I need more than 1/2 watt.

[LxMike]

maybe your car just doesn't like that setting. resistors are cheap so you might have to try a few diff ones.

i done some checking around and have found that my iat is integrated with my mass air sensor. i found a site that shows a pot (potentiometer) installation, but i'm not into cutting wires. oh well can cross that exp off my list now.

[cfg83]

LxMike -

Originally Posted by LxMike

maybe your car just doesn't like that setting. resistors are cheap so you might have to try a few diff ones.

i done some checking around and have found that my iat is integrated with my mass air sensor. i found a site that shows a pot (potentiometer) installation, but i'm not into cutting wires. oh well can cross that exp off my list now.

That makes sense. If you picked a resistor based on the Saturn mapping, then it is probably incorrect.

Question for others : Does the behavior imply rich (super cold IAT reading) or lean (super hot) running?

I have been looking on the net, but I can't find a "1993 Honda Accord" IAT temp/resistance map of any kind. Sorry .

CarloSW2

[repete86]

I found one when this was first brought up a few months ago, and I remember it being very close to the Saturn one.

EDIT: on this site, SVOboy posted a graph of OBD0 temperature/resistance and it's pretty much identical to that of saturn.

http://www.gassavers.org/showthread.php?t=464

[basjoos]

If I decide to do this mod, I would get a 5K ohm audio-taper pot (Radio Shack), a 4-pole 2-throw toggle switch, a 2 sets of 2-conductor quick connectors, and a 4-conductor cable, so that I could use the pot to dial in the desired faux-temperature and use the switch to select between the pot and the IAT sensor inputs. I would mount the pot and switch on my dashboard. Leave the IAT sensor connected during startup and during the steep hillclimbing portions of my drive and switch to the pot during gentle cruising on the flats and on lesser grades.

cfg83, do a search for "TA sensor" since that is what Honda calls the IAT sensor on their engines. On my 92 Civic, it is on the side of the intake manifold.

[usedgeo]

Originally Posted by repete86

Okay, I installed the resistor. I had some major problems, and my mileage plummeted. The car wouldn't shift lower than 3k rpm, and my check engine light is now on. I'm going to take a closer look at it tomorrow to see if I can fix it. I used a 1/2 watt 150 ohm resistor. It looks like on the cable that connects to the IAT sensor, there are three connections. One is the ground, and maybe I ran the resistor into the wrong holes, or maybe I need more than 1/2 watt.

I suspect that since it has three wires it might have a reference voltage, ground, and signal. If so this will be much harder to trick and if you get the resistor in power and ground it may get a bit hot or worse. You might want to review an electrical schematic pretty close for this one. There was a brief discussion of this last summer I found googling Honda IAT Sensor

http://www.gassavers.org/archive/ind...ent/t-149.html

Maybe this is more beneficial to a Saturn.

Ernie

[cfg83]

repete86 -

Yup, it's near identical, so you must have been in the 200's I think.

basjoos -

Sounds like you'll soon be publishing a GasSaver's product . Until then, here's a more primitive way of doing the same thing. Route the "outside" thermometer of an inside/outside thermometer to the location of the IAT sensor. Attach the audio-taper pot to the IAT input cable. Start the car up and use the ScanGauge to manually "match" the potentiometer to the outside temp reading. Deviate or conform to the real IAT as desired .

Off to troll for "TA Sensors".

usedgeo -

3 wires? Honda's too smart for me.

CarloSW2

[DRW]

basjoos wrote:"Leave the IAT sensor connected during startup and during the steep hillclimbing portions of my drive and switch to the pot during gentle cruising on the flats and on lesser grades."

I'd recomend using it to lean out the mixture slightly during startup since that's when the ecu is running very rich. Plus it's in open loop, so it's not looking at the O2 sensor until the engine temp comes up a little more, so the ecu won't try to compensate for any changes yet.

I've been doing something similar when I start my car everyday. I have an Apex SAFC air/fuel controller on my dash. I'll usually subtract about 10% fuel before starting my car in the morning, then adjust it back to normal when the O2 volts start cycling in closed loop, which usually happens when the engine coolant reaches 88*F. It starts and runs just fine.