Everything I read about tuning says how dangerous it is to your engine to run too lean. I understand that running lean creates a lot of heat and will destroy your engine. My question is why does running lean create so much heat?

How lean is too lean? I am using the highway mode one my prom and I want to know how lean I should go.

 

At the typical stoichiometric air fuel ratio (14.7:1), that is where the maximum amount of reactants turn into products (i.e., petrol and O2 ---> H2O & CO2), so it stands to reason that is where the maximum amount of heat is generated.

In real life, I believe that the highest exhaust temperature occurs at 15.0:1 AF ratio.

Typical AF ratios for best power (and little chance for detonation) occur between 11:1 - 12.5:1. This somewhat correlates to an exhaust temperature of 1200-1400°F. The excess fuel that is not combusted extracts some of the heat of combustion, lowering exhaust temperatures. When one leans out to say 14.7:1, exhaust temperatures can climb to 1800-2000°F.


How lean is too lean? No easy answer. Exhaust temps are the best way to tell. Also part throttle derivability. If it stutters, you’re too lean. Detonation can indicate that things are getting a little hot in the engine.

 

Does the computer automaticly come out of highway mode if detonation is detected?

 

If the computer detcts detonation it pulls out timing until the detonation goes away.

 

I was wondering if the computer comes out of highway mode if it detects detonation