Some years ago on our Dodge trucks, we used to place a 10K ohm resister inline on the IAT sensor to make the ECU believe that intake charge was about 40* F cooler than actual. This had the effect of influencing the fuel/air ratio and timing. Essentially, the ECU believed it was cold outside, and would not retard timing or richen the fuel ratio as compared to the hot summer. Those ECUs depended on the IAT to prevent a detonation condition from occuring-- the ECU played it "safe" so to speak, and would retard timing and richen the fuel mixture, just because it though detonation MIGHT occur.

Naturally, detonation was a concern and was experienced by a very small number of folks in very, very warm climates. Most of us never experienced a problem, and the mod gave us a better throttle response, better fuel economy, and a small boost in HP-- at least during the summer months. Some folks would even relocate the IAT from the hot intake manifold, to their CAI, just behind the filter.

Those Dodge engines were not equiped with knock sensors. The IAT was the only sensor the ECU used to prevent knock, so one had to keep an ear open for ping/knock/detonation. I personally had great success with it, and never had a problem... even in 95* F+ summer, pulling a 4000lb trailer, uphill, with my A/C on-- honest!

I understand the MINI has knock sensors? If so, then would the ECU then retard timing and dump fuel when it senses detonation from the sensors? And if that's true, could we not play with IAT on our MINI's and achieve a similar effect?

I'm tempted to experiement, but would appreciate anyone's feeback before I begin.

Cheers,

 

hrmmm....

sounds pretty risky to me.

knocking is bad....even if you catch it right when it starts...Its still very BAD.

I would think that it might extremly increase the temp of the engine on a hot summer day.

what was your oil temp reading on that hot day with your dodge truck towing 4000lbs?

 

Yep, knocking is bad for sure, but the difference here as compared to the old Dodge is that our MINI's and most all cars built, certainly since OBDII of the mid nineties have an elaborate knock prevention system.

There is a knock sensor attached to the engine block that is, in essence, a microphone. If knock is detected, the ECU takes immediate steps to prevent it by retarding the timing and whatever else necessary to prevent it.

This system is why you can, if you wish, use regular octane fuel in your car without risk of engine damage. Since the timin is retarded if you use regular, it is false economy since your timing is retarded thus decreasing fuel mileage.

There are other electronic fuel injection cars that have had experimentation with the IAT and other circuits to fool the system. The problem with the IAT or other temp sensor circuits being tricked is that it prevents the system from going into closed loop operation. In closed loop operation, the timing and fuel parameters run from a map, or to software folks a "lookup table" rather than constantly adjusting these parameters based on O2 sensor reading.

This means that if the ECU senses that the engine is cold it doesn't automatically OPTIMIZE these settings. It is very possible that you could cause all kinds of neat performance gains, but at what cost? The closed loop operation extends engine life, spark plug life and typically provides better fuel economy under cruise conditions. Once you disable the system from closed loop operation you have no way of knowing if the system is running too lean, too rich and how much. If you have access to a dyno and mixture analyzer, you could do some scientific experimentation and possibly come up with a usable and beneficial combination.

Without such facilities and time to spend, your dealing with guesswork.