Fooling the Inlet Air Temp (IAT) sensor?
Cadillac
 

Cadillac Forums | Help Us Help You | Advertise | Cadillac Parts | Cadillac News | Cadillac Classifieds / (Old System)

Cadillac Technical Archive | Cadillac Dealers | Cadillac Reviews | Cadillac Dealer Reviews | Cadillac Vendors

CadillacForums.com is the premier Cadillac Forum on the internet. Registered Users do not see the above ads.
+ Reply to Thread
Page 1 of 3 1 2 3 LastLast
Results 1 to 15 of 31
HT4100 4.1, 4.5, 4.9 Discussion, Fooling the Inlet Air Temp (IAT) sensor? in Cadillac Engine Technical Discussion; A lot of heavily advertised products are just a resistor in series with the IAT sensor. This fools the car's ...
  1. #1
    Notaguru is offline Cadillac Owners Fanatic
    Automobile(s): 1990 DeVille
    Join Date
    Feb 2009
    Age
    75
    Posts
    181

    Fooling the Inlet Air Temp (IAT) sensor?

    A lot of heavily advertised products are just a resistor in series with the IAT sensor. This fools the car's computer into believing the ambient air is cooler (or warmer? I'm not sure) than reality, and the result is a different Fuel:Air mixture.

    Claims include higher horsepower, better mileage, and improved hair growth.

    What's going on?

  2. Remove Advertisements
    CadillacForums.com
    Advertisements
     

  3. #2
    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
    Automobile(s): White Diamond '03 DHS (with DTS floor shift)
    Join Date
    Jun 2004
    Location
    Woodstock Ill.
    Age
    66
    Posts
    72,329

    Re: Fooling the Inlet Air Temp (IAT) sensor?

    It fools it into believing that it is cooler, thus a richer mixture, thus LOWER mileage. You can't have your cake and eat it too. Most of that stuff falls into the same category as the Tornado and the fuel line magnets. Remember what P.T. Barnum said.

  4. #3
    Notaguru is offline Cadillac Owners Fanatic
    Automobile(s): 1990 DeVille
    Join Date
    Feb 2009
    Age
    75
    Posts
    181

    Re: Fooling the Inlet Air Temp (IAT) sensor?

    Ranger, thanks.

    Does it make sense to put a resistor in series with the IAT, and switch it in/out? That would permit the car to run normally unless the resistor were kicked in, which could be automated by activating the switch with the throttle linkage.

    And what about my bald spot?
    Attached Images

  5. #4
    cadillac_al is offline Cadillac Owners Connoisseur
    Automobile(s): Cadillac 78 Seville, 78 Coupe de Ville, 92 Sedan de Ville
    Join Date
    Feb 2007
    Location
    Maine
    Age
    52
    Posts
    2,710

    Re: Fooling the Inlet Air Temp (IAT) sensor?

    I don't believe richer is faster. The law of the land is "let the buyer beware". There are no truth in advertising laws unless it is health related. Companies can claim anything in their advertising, it's called puffing, and it is up to the buyer to beware.

  6. #5
    Notaguru is offline Cadillac Owners Fanatic
    Automobile(s): 1990 DeVille
    Join Date
    Feb 2009
    Age
    75
    Posts
    181

    Re: Fooling the Inlet Air Temp (IAT) sensor?

    I may do an experiment.

    I'll put 2-3 gallons of REGULAR fuel in the tank, and it should ping. After I add that series resistor, it'll run richer and should NOT ping. If that "works", perhaps I can begin using regular gas, activating the series resistor only when there's enough throttle to ordinarily cause ping.

    Make sense?

  7. #6
    steelybill is offline Cadillac Owners Enthusiast
    Automobile(s): '85 FWD fleetwood, '93 fleetwood Bro
    Join Date
    Mar 2009
    Location
    mich
    Age
    82
    Posts
    726

    Re: Fooling the Inlet Air Temp (IAT) sensor?

    We used to cool the intake manifold on the SB Chevys with dry ice at the drag strip, for a denser air/fuel mixture, and it did help. Anything like that would reduce mileage though, so we are sort of stuck with what we have.

  8. #7
    Notaguru is offline Cadillac Owners Fanatic
    Automobile(s): 1990 DeVille
    Join Date
    Feb 2009
    Age
    75
    Posts
    181

    Re: Fooling the Inlet Air Temp (IAT) sensor?

    The idea is that the car would run fine on regular except for 0.1% of the time when the hammer is down. If the ECU can be fooled into thinking the IAT is reporting cold air at those moments, the system will go rich - and that will cool the combustion chamber and reduce pinging. As mentioned, the resistor would be switched into the circuit only when the car approaches full throttle.

    Does this make sense?

  9. #8
    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
    Automobile(s): White Diamond '03 DHS (with DTS floor shift)
    Join Date
    Jun 2004
    Location
    Woodstock Ill.
    Age
    66
    Posts
    72,329

    Re: Fooling the Inlet Air Temp (IAT) sensor?

    Everything on these cars is computer controlled and intertwined. Usually when you try to fool them, you end up causing more trouble than you fix. What engine are you talking about? What are you trying to accomplish? Run faster? Run regular? As mentioned, I doubt it will make you run faster. Maybe just the opposite. I seem to recall someone doing that before and having that effect. Sub may recall it. If you are trying to run regular, what are you accomplishing? Cheaper gas (regular), but more of it (richer). Personally, I'd leave it the way the GM engineers designed it.

  10. #9
    Notaguru is offline Cadillac Owners Fanatic
    Automobile(s): 1990 DeVille
    Join Date
    Feb 2009
    Age
    75
    Posts
    181

    Re: Fooling the Inlet Air Temp (IAT) sensor?

    When you say "intertwined", perhaps you're talking about the combination of input sensors (IAT, MAF) and output sensors (O2), which the ECU reads to control fuel from the injectors. It's not really a closed loop system, nor is it very complicated.

    I have experience in successfully modifying and racing an '87 Buick Grand National (hi 11's) that is not less complex than my '90 Deville, so at least I know which end of the soldering iron to grab. The simple modification suggested above is not designed to achieve more speed, but to permit safe usage of low octane fuel while preserving the performance of the car when it's needed. Going rich will reduce pinging, but I don't know whether the difference will be significant. This little modification probably won't damage anything - and, of course, it can be reversed in seconds.

  11. #10
    Ranger's Avatar
    Ranger is offline Cadillac Owners Member
    Automobile(s): White Diamond '03 DHS (with DTS floor shift)
    Join Date
    Jun 2004
    Location
    Woodstock Ill.
    Age
    66
    Posts
    72,329

    Re: Fooling the Inlet Air Temp (IAT) sensor?

    Well, it sounds like you know more about it than I do, but as I mentioned it seems futile to me. If in order to burn cheaper gas, you have to burn more of it, you are not accomplishing anything. In fact, you might burn so much more as to actually cost you MORE. Just thinking out loud.

  12. #11
    Sevillian273's Avatar
    Sevillian273 is offline Cadillac Owners Connoisseur
    Automobile(s): 69 Thunderbird | 90 Seville | 89 Marquis | 72 Torino
    Join Date
    Oct 2008
    Location
    Palm Bay, FL
    Posts
    2,022

    Re: Fooling the Inlet Air Temp (IAT) sensor?

    This is a shot in the dark, but..... Is it possible to use a racing ignition box that can retard/advance the timing from the drivers seat? Maybe something designed for use with boost/nitrous? You could retard for regular and advance for premium. Just a thought.... I dont think it could improve hair growth, though...

  13. #12
    Notaguru is offline Cadillac Owners Fanatic
    Automobile(s): 1990 DeVille
    Join Date
    Feb 2009
    Age
    75
    Posts
    181

    Re: Fooling the Inlet Air Temp (IAT) sensor?

    I installed a timing controller in the Buick - it worked well, but was costly and complex.

    In this Caddy, the end result will be the same amount of regular gas as the high-test gas that I'm currently using EXCEPT when the throttle opens wide and the IAT resistor is kicked in, thus enriching the mixture. It will happen ONLY under conditions of hard acceleration.

    I drive pretty sedately, so expect no significant change in mileage.

  14. #13
    cadillac_al is offline Cadillac Owners Connoisseur
    Automobile(s): Cadillac 78 Seville, 78 Coupe de Ville, 92 Sedan de Ville
    Join Date
    Feb 2007
    Location
    Maine
    Age
    52
    Posts
    2,710

    Re: Fooling the Inlet Air Temp (IAT) sensor?

    So your car pings on regular fuel Notaguru? You must live in a hot climate. Why not try a cooler thermostat? Up here in Maine it rarely gets in the high 80's and my Deville never pings on regular. Maybe stop and go driving in heavy traffic will get them hot enough to ping but my car doesn't see much of that. Maybe it's just carboned up and needs a good flogging. It sounds like the GN runs nice; another nice ride.

  15. #14
    Notaguru is offline Cadillac Owners Fanatic
    Automobile(s): 1990 DeVille
    Join Date
    Feb 2009
    Age
    75
    Posts
    181

    Re: Fooling the Inlet Air Temp (IAT) sensor?

    Quote Originally Posted by cadillac_al View Post
    So your car pings on regular fuel Notaguru? You must live in a hot climate.
    It pings only on the combination of REGULAR GAS + HARD ACCELERATION. That's why (today, hopefully) I'll install that experimental circuit, squirting additional fuel only when past 3/4 throttle.

    I don't know whether the ECU response to IAT changes is instantaneous, but will find out.

  16. #15
    Racer704 is offline Cadillac Owners Member
    Automobile(s): 97 ETC
    Join Date
    Jun 2006
    Posts
    83

    Re: Fooling the Inlet Air Temp (IAT) sensor?



    The best thing to do here is make a true cold air intake system. I dont mean these underhood metal jokes that they sell on Ebay which they dont make for ETC or anything like that. now to do this you need to know you will have to clean it monthly. I made one in 02 for my 97 ETC as I was board and wanted to see if i could do it....

    Well I did and on a whole it lowerd intake temps greatly and depending on ambient where it is and really makes a big differance in the midrange and I did pick up almost 2 MPG HWY. I left the air intake sensor under the hood but its in a 2' 4" I think cant remember PVC tube that conect to the original flexable coupler and the other end i have attached to flexable dryer duct hose that goes out thru the headlight assem. to the front of the grill. Then i mounted a 10" K&N filter to the center support and its half in the grill and half under the bumper cover.

    I also sheilded the radiator and hoses from the intake ducting also with flashing so the even on hotest day at idle it its still cooler then was before. i cant remember exact numbers but performance is what i looked at also. I used my Snap On MT2500 scan tool to monitor things when i did this and also used a seat of the pants and then milage as I am always on the road. now being out fron tlike this requires maintance every 4 to 6 weeks. I clean it,if not after 8 to 10 weeks mileage drops ...I guess milage wise I am saying about 5 to 6 thousand or depending on your driving. Its outfront and if it looks nasty then clean it.....so there you have it you want something you need to give up something. Colder true intake air will give you many things but fooling a sensor will only fool you in the long run and probably cost you more in the long run with fuel,O2 sensors and cat problems........

    I have run what ever is the cheapest meaning 87octane since 2000 and never have I heard the 1st ping. I live in the Crolinas so its hot here...You have other issues if you hear pinging in that engine.....still 28mpg at 75MPH avg 238,000 miles and yes it burns oil.....leaks it too but runs great still

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.
If you do not want to register, fill this field only and the name will be used as user name for your post.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.



Bookmarks

Cadillac Posting Rules

  • You may post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
Read about Lincoln | Buick | Kia Forte Forum
Need products for your Cadillac? Check out your options at the links below:

custom floor mats | Cadillac Chrome and Black Chrome Wheels | window tinting