AIT mod (eBay, +20hp etc etc): REVEALED
 

well I know some of you were curios, and this will be a much cheaper option..


sorry to everyone who tries to make a profit on these!!!

the RESISTOR mod is rated at 100k ohms. (Brown, Black, Yellow)

thats it. plug it into the AIT plug and your done.

I'm confused?

im talking about these

http://cgi.ebay.com/ebaymotors/ws/eB...RK%3AMEWN%3AIT

Old news...

meh, to lazy to do it so i bought it :p

Just to clarify, this is the air temperature sensor on the dynamic chamber, and it actually does help noticeably?

-=Russ=-

Yes, its in the AFM, it kicks your maps around a little when the weather is cold, IDK about the whole 20hp gain though. I wish i would have thought to do this while i was on the dyno last week. It would have been cool to see what the real number gain was.

Ok, so I'll throw out some thoughts on why this works, and some conclusions reached from the FSM:

100kOhm resistance on this sensor tells the ECU that the intake air is FSCKING COLD. Probably well below freezing, and most likely pegged low (as cold as the ECU can adjust to).

The density adjustment would most likely be made off the intake air sensor on the airflow meter - measuring the temperature of the air that the airflow meter is sensing will allow the ECU to do the density conversions needed to interpret the AFM signal. Fuel delivery will (should?) be based off the amount of air coming in, regardless of temperature. So, I don't think this particular mod will adjust the fuel mixture much, if at all. The temperature of the air in the dynamic chamber doesn't change how much air actually came into the engine. Also, NAs run terribly rich to begin with. Adding fuel would most likely reduce power output, and supposedly this mod actually has produced dyno gains (I think I saw 7 hp in another thread - not bad for a $0.10 part).

This leaves timing. The temperature of the air going into the intake ports *WILL* affect the tendency of the engine to detonate. Hot air = more chance for detonation. The normal solution to this is to retard timing. I'm guessing the ECU uses this sensor mostly for retarding the timing with hot intake air - a sort of preemptive knock sensor type device. So, telling the ECU that the air coming in to the engine is darn cold would tend to let it advance the timing as much as possible. This would tend to increase the power output, especially in warmer weather or when the engine is heat soaked. I've noticed before that my engine seems to lose power to some extent as it gets hot (especially during the summer). I know that the hotter air is less dense, but it's a pretty noticeable difference, and the ECU retarding the timing would definitely cause this.

Does anyone have the tools to measure timing advance under load? It would be interesting to see what this mod actually does.

I'll be running to Radio Shack tomorrow for a resistor or two, and see what kind of difference I notice.

Oh, and I'll put an "ARCHIVE THIS" vote in.

... lying to the ECU about the amount of air coming in (SAFC-II), lying to the ECU about the temperature of the air coming in... I'm so ready for a standalone.

This is a continuation of the (derailed) thread at https://www.rx7club.com/2nd-generation-specific-1986-1992-17/intake-chip-433244/

-=Russ=-

No. This mod doesn't affect the intake air sensor in the airflow meter. It affects the inlet air temperature sensor on the side of the dynamic chamber, under the BAC (at least on the S4 NAs, not sure where it plugs in on the S5s).

Also, the FCs don't have "fuel maps", per se. They convert the airflow meter readings into mass airflow readings (using the air temperature as detected at the airflow meter), and deliver fuel based on that. It's modified slightly by other parameters (I believe manifold pressure comes into play somewhere, and most likely RPM), but it's not a fuel map in the normal sense of the phrase.

-=Russ=-

yeah, it connects into the plug on the side of the throttke body, not the air flow meter

I'd like to see it MAKE 20hp +!

Just fooling the air temp and triggered a more rich condition does NOT automatically mean it will make more power.

Even if you revealed the secret, it doesn't mean squat.


-Ted

I didnt say it did Ted... Im jsut trying to save people some money.. no need to pay 10 bucks for a 12 cent part.

so it is more effective on the s4 na's? i figured putting that on would most likely hurt your engine but im also kind of new to the rotaries.

but if it's warm outside and ur telling the engine it's Cold air..

wont u just being makin the car richer? (for no useful reason)

i guess all these trinks kinda go out the window when u have a piggy back FC or something

Extra resistance = ECU thinks air is colder = ECU thinks air is denser = ECU thinks there is more air than normal = ECU injects more fuel than normal = rich mixture = LESS POWER!

Don't be fooled into a scam that offers the exact opposite of what it promises. Just adding more fuel will always reduce power. Always has, always will.

No!
It's be thoroughly documented that ALL the FC NA's run rich already.
Running a fuel computer to lean out the RPM ranges will easily increase power.

Putting that resistor to fool the air temp sensor will just supress more power, since it's running even richer.


-Ted

100K is radically too high, and will put the ECU into a fault mode on that wire thinking that the sensor is busted.

7.5K would be the absolute highest you would want to go, with a 4.7k much better because then the sensor would still work (just be about 50F cooler in reporting).

Did anyone read my theories on how it works? I'm pretty sure the air density correction (and therefore fuel delivery) is controlled by the sensor in the airflow meter. If ambient air temperature is 70F, the amount of air pulled in at a given AFM opening is the same, regardless of the actual temperature going into the intake ports.

Also, in the other thread (linked in one of my posts), someone recorded a 7HP dyno gain from this. It's not 20HP, but it's still a respectable amount. I agree entirely that the NAs run rich already, and adding fuel will reduce power output. So, to get a 7HP gain (which I would say is probably large enough to be outside the realm of random noise, especially considering everyone believes the power output should drop), something has to be happening.

I'll have more data later tonight. I'm planning to run to Radio Shack and snag some resistors. Right now, my SAFC-II is tuned to run the engine slightly lean of stoich in normal highway cruising (I disconnected the O2 sensor input from the ECU, so it stays in open loop mode for now). I can monitor the narrowband O2 sensor output and see roughly what the fuel mixture is doing. If, in fact, this mod does increase the fuel delivery, I'll be able to determine this based on the O2 sensor output. I'm not convinced that the upper intake manifold sensor does much, if anything with fuel delivery, but that it is used mostly for timing advance.

Short of a timing light on a dyno, is there any good way to determine what the actual advance is under load?

-=Russ=-

Are you discussing S4 or S5?

According to the S4 FSM (Page 4A-81), the resistance of this sensor should be as follows:

20C/68F: 41.5 +/- 4.15 kOhm
50C/122F: 11.85 +/- 1.19 kOhm
85C/185F: 3.5 +/- 0.35 kOhm

If you put a 7.5kOhm resistor in, you'll be telling the engine that the intake air is somewhere around 70C, which kind of defeats the purpose.

100kOhm would be a reasonable value for sub-zero temperature reporting. I need to head to work, but in another thread a while back, someone generated a quadratic formula for this sensor based on the FSM data. I'll dig it up in an hour or two.

-=Russ=-

This "mod" + the leafblower supercharger + AFM gear mod + the Tornado + a dyno would all make for a good story in RXTuner. What were some of those other suspect mods?

the tornado???...its a joke...i had it in my car...didnt do a damn thing....

Of course it's a joke that would be the point of the article :D My personal favorite has been the electric leafblower supercharger. I'm surprised it hasn't popped up this year.

B

I'd really like to see proof of that.
Variables such as water temp cause easily cause power deviations like that.

If all things are kept constant, I would highly doubt an NA would gain anything more than 1hp just by fooling the air temp sensor...



-Ted

It depends on what that particular sensor is doing. I see no reason why it would affect fuel delivery much, if at all. However, it would be in a perfect place to be able to adjust timing, and I think we can all agree that the NA '7s will gain a bit of power from advanced timing. My belief is that this mod prevents the ECU from retarding timing at higher intake air temperatures. This also would explain why on eBay they're not sold for turbo vehicles - advance timing on a turbo, hit some good boost, pop an apex seal. The FC ECUs are incredibly conservative with fuel delivery, and apparently timing as well (from the gains seen by advancing the timing).

As I said, I'll get numbers later tonight with regards to fuel delivery.

-=Russ=-

No I am basing it on the AFM, because the dynamic chamber temp sensor does next to nothing.

You can check that with a timing light yourself (I have). The dynamic chamber temp sensor is used for hot start. Not air density.