IAT Sensor Mod (Resistor Mod)

[SVOboy]

I was going to try out larry's IAT mod on my friends saturn tomorrow, I even had two 220 ohm resistors hooked up in parallel to do it:

But he wussed out last minute. So I have a few questions.

Has anyone besides larry done this?
To larry: I know you said the heat isn't different, but are you worried about running too lean or oxidation or anything? How many miles have you been running this set up? I know you have EFIE, but with this can you figure out your AFR? That's all I can really think of now, but mehbe I'll ask some more later. I'd love to try this, just wanna mehbe get some answers to convince this guy since I'm in the middle of my acetone test.

EDIT: If anyone wants a set of resistors in series that add up to 110ohms (like the ones on the bottom) I have tons of resistors around and I'd be willing to send some out to you so you don't have to buy a bunch of crap or locate a bunch of crap. That way we can also get you on testing a bit faster. Also, if you're non obd0/1 honda, I could prolly figure out what resistance to use, but it'd take me some time if possible.

[diamondlarry]

I have been running this mod since April. Up until 3 weeks ago, I drove 200 miles/week just for work. With all of the other running around, it probably ended up being 300-350 miles or more a week. At 300 miles a week this figures out to around 6,000 miles. Back when I did my sparkplug testing, I had my plugs out fairly regularly and never noticed any signs of running severely lean. As far as AFR goes, I don't have any way to check that.

[SVOboy]

Yeah, I'll show this to him and try to sway him, but I might just wait for my own testing to be done for it.

[SVOboy]

What's the best way to figure out the resistance I need for my stuff? Should I boil some water and dip the sensor in there and measure the resistance with a multimeter?

[diamondlarry]

That should work.

[SVOboy]

I don't have a multimeter handy, so I'll do it tomorrow hopefully and post up the results. I'm still hoping on acetone, but it seems like every time I start the car the needle drops randomly and won't go back up to where I started it from so it worries me, haha.

[SVOboy]

So, it's 74 degrees out now and my multimeter just read 61.5 ohms of resistance across the IAT sensor. So I'm wondering if the relationship is linear or what, cuz if it was I could just heat it up a bit and test it and then make a line to figure it out, but I think it'll be above 110 ohms.

[SVOboy]

Okay, forget what I measured just now, cuz it's no good. Here's the real numbers for the 88-91 Honda D15B2:

100 ohms = 248 degrees
20,000 ohms = -40 degrees

Seems that all obd0 and obd1 stuff uses the same values, so that should be good for all the honda stuff at least, I dunno about obd stuff outside of honda.
I'll see if I can get a b18c1 thing for flatland...

[SVOboy]

This is a picture of my IAT for Matt. This on a 91 crx dx with a d15b2 and dpfi.

[dfoxengr]

just a quick resistor ?

im not so good with electronics, but if i wanted a 12v power wire in my car to be reduced to say 3v or 6v or 9v, how would i do that?