iat sensor question
 

I have a 2003 Chrysler t&c with the 3.8. I recently read somewhere else about unplugging the iat and putting a resistor in instead, the theory behind it made sense so I tried it. I put a 5.6k in. the check engine light came on and after about 35 miles the light went off. Initially I thought I was getting better mileage based on my factory overhead mileage avg reading, but I wasnt sure so I took out the resistor and plugged the iat sensor back in. Now my check engine light came on and hasnt turned off. Should I be concerned, should I put the resistor back in? any ideas?

how did it change the car?

Well I put the resistor back in and the check engine light turned off and my mpg avg went up as well. Any negative long term effects from mortifying the iat

It is very unlikely to make a real difference in mileage because the iat is only a part of a bigger system, the computer relies more heavily on the o2 sensors. Pop the resistor out and the cel should reset after 3 normal run cycles.

Tweak any signal but the O2 sensor and it will compensate pretty quickly. Tell the MAF there less air coming thru the O2 sensor will figure it out and fix it to maintain Stoinch, except when running closed loop, but even then the LTFR will compensate some what so still not going to fake it out go run lean.

Don't measure MPG using the OEM electronic fauges since you have modified data inputs fornthe ECU. Use the pump and mileage. I don't think you can be sure the benefit has been real, or as large as you think, based on the OEM gauge alone.

In 1999 I had a 80s V6 fuel injected Camaro that had a malfunctioning IAT. The IAT was telling the computer the air was a lot hotter than it actually was, for some reason that leaned out the air fuel mixture, it ran lean and burned all the exhaust valves.

Before,the mod my gauges avg stayed at 22.8 mpg, and that coincided with mileage and the pump pretty close within .2 so now the gauge avg is 25.4. Maybe a placebo effect, am I driving better? Idk. If this is the case how do we fool the o2 and maf? I also modified my airbox, cut a slot in the resonator part allowing air to come under my hood straight into the airbox, pre filter of course

Trying to fool the electronics is one of the more difficult ways to get higher MPG. Every electronic sensor signal mod has other consequences in the engine management system. You want to be careful with your car and safety. There is much easier to reach "low hanging fruit" ... take a look at this list (have you already?): 65+ Vehicle modifications for better fuel economy - EcoModder.com

And the hypermiling tips too: 100+ Hypermiling / ecodriving tips & tactics for better mpg - EcoModder.com

Would warm air intake do the same thing as what I want the resistor to do? Are there any programmers that work for fe? I just think covering up things reducing drag isnt going to do a whole lot, or will it?

If you drive a good bit of highway then aero dynamic improvements can give the best return for the money.

Not exactly. When a WAI works it probably works by reducing energy lost to pumping air into the engine for burning gasoline. Lots of people think the warm air, because it is thinner and will cause the engine to lean out a little, that that is what saves fuel. But to get the same power you'll step on the accelerator harder. So the real gajn, when it happens, is probably from the fact that the throttle plate ends up more open because you are depressing the accelerator pedal further. It's therefore less of an obstruction. Hence, you reduce a drag on the engine ("pumping losses").

I saw a small benefit after testing, others have not. You could experiment and report your findings...

One plus of a WAI over a resistor is that the ECU sensor data is correct. The computer knows the IAT is higher, and the IAT is actually higher. It will adjust safely.

James

I happen to have a 5.6k resistor inline on my IAT sensor. It is on my Ford Escort ZX2 with a 2.0 Zetec. This mod gives more timing on our cars by telling the ECU that the air is colder than it actually is, along the lines of -10°F with an ambient of 60-70°F. The colder the air, the less modification to the signal there is, and vice versa. The IAT is not used for determining AFR on my ZX2, so the computer does not compensate for it. I'm unsure if your Chrysler has the same set up.

As for you check engine light, the IAT wires could have a bad connection and trigger the CEL. I would start there. Actually, go to an AutoZone, Advance Auto, or O'Reillys and let them see what's causing the CEL for free, and report back to us :)

I saw the thread on the TeamZx2 forum. The guy who did the research (Mechtech) really seems to know his stuff. I asked about my Ranger and after some research and question asking on other sites I am currently trying this one out also. I have only run about 3/4 of a tank through but so far it looks "promising". I'll know more with a few more tanks. My "system" is simple. Put in 10 gallons and try and hit 300 miles or better. Not very scientific and I'm sure someone on here will be sure and point that out, but it's been better than "ball parking it" for for almost 3 years. I did some faster than normal interstate driving this weekend and that may have thrown off the numbers, but for now I'm keeping the resistor in.

Here's a link to the thread. It's VERY long (70 pages), but you'll have to wade through it and pick out the important information.

40+ Mpg