FAT mod

Testing the impact of the modification of the IAT and fuel temp sensors on ignition timing for the TDI. I'm switching on an off 18k ohms resistors inline with the sensors. The marginal idle at the end along with the low gph are due to the modification of the fuel pump piston movement sensor, to illustrate that the ECU did not modify the IQ with the FAT mod.

Category:

Autos & Vehicles

Tags:

• TDI
• Fuel
• Air
• Temperature
• Ignition
• timing

[VeeDubTDI2]

Why not just tune the ECU?

[Greg11980]

For those that dont know Diesel fuel is measured in Cetane not Octane.

[Greg11980]

For a gas engine you are supposed to use around a 4.7K ohm resistor I think an 18K ohm resistor is probably way to high a resistence to use. I did notice you were using a TDI diesel.

[jaydnisevil]

Pretty much, its a pretty povo way of tuning your car..Would work fine provided he is using higher octane fuel. More often than not, the ECU will work around it over time :(

That tone in the background is REALLY anoying.

[sodapop503]

He must be tuning for power. The resistor makes the ECU think the incoming air is colder and more dense, thus the ECU adds more fuel, and adjusts the timing, because there is less risk of detonation.

[crazychickenhead]

I've been monitoring my IAT with a AEM FIC. It stays pretty stable throughout my logs (i log every 10ms) but generally the resistance goes down the longer I drive. I've noticed that intercepting and adjusting this sensor's reading doesn't seem to have much of an effect on anything. Have you noticed anything worthwhile on this sensor? Are you tuning for fuel economy or power?