Intercooler question

[[HTi]Johnson]

Does having an intercooler on a car that originally didn't have one cause it to be too lean or rich?

 

There's all that space the the turbo has to fill before it gets to the intake manifold. I know there is ambient air in it...but it still has to compress the air in the IC to get the intake compressed. Maybe I'm just thinking wrong?

 

Thanks for your time,

Justin.

[nkx]

i would tend to think it would lean the afr out. more o2 because the air is now more dense (cooler) than when it was originally compressed.

[NorthWet]

Engine is breathing 6-10K liters of (STP) air per minute at max revs-boost... a liter or two of air, with plenty of time for pressure rise, is not going to make a real difference in AF ratio. It *can* add a little lag.

 

Density does not enter into it, as the MAF has already dealt with quantity of air. It is possible to stuff more oxygen into the engine than the injectors can deliver fuel for, causing a full-power lean-out.

[Phizinza]

I bet your O2 sensor in your exhaust would tell the comp how much (more/less) fuel to put in and you'd see no difference at all.

That's why EFI cars have all those sensors.

[nkx]

I bet your O2 sensor in your exhaust would tell the comp how much (more/less) fuel to put in and you'd see no difference at all.

That's why EFI cars have all those sensors.

 

i dont know how the old gen ecus work with this, but on my wrx, there is a point where the ecu ignores the o2 sensor and delivers fuel based on preset maps. (open loop/closed loop)

[NorthWet]

i dont know how the old gen ecus work with this, but on my wrx, there is a point where the ecu ignores the o2 sensor and delivers fuel based on preset maps. (open loop/closed loop)

Old Gens are supposed to go open loop when manifold pressure goes slightly positive (based on a pressure switch similar to the one that turns on the "TURBO" indicator on the dash).

[daeron]

random offtopic.. TURBO idiot lights always seemed stupid to me.

 

my friend had a turbo volvo, and that came with a manifold pressure gauge that was un numbered... just had a two colored bar on it, like the blue and red bars on a heat/cold lever.... just, dumb. put numbers on it, guys!!! its SIMPLE!

 

sorry. had to say it.

[XT&A4ME]

fuel ratio is fuel ratio. 16 to one, compressed, is still 16 to one. It only occupies a smaller space. When cooling it, you aren't removing any oxygen molecules, nor adding any. This shouldn't be an issue unless the IC is AFTER a carburator or injector body. Then,,,, fuel will wet the walls of the IC which could / would lean out the mixture. That would be my understanding.

[nkx]

fuel ratio is fuel ratio. 16 to one, compressed, is still 16 to one. It only occupies a smaller space. When cooling it, you aren't removing any oxygen molecules, nor adding any. This shouldn't be an issue unless the IC is AFTER a carburator or injector body. Then,,,, fuel will wet the walls of the IC which could / would lean out the mixture. That would be my understanding.

fuel does not go through the turbocharger in a fuel injected system. youre only cooling the air in this situation.

[daeron]

fuel does not go through the turbocharger in a fuel injected system.

 

he was making a theoretical statement i think, to illustrate a situation where intercooling _would_ lean the mix... As northwet pointed out the AFM has already metered the mass of air that the engine is breathing in. the boost and the space that air occupies on its way to the engine doesnt matter, its a matter of metering flow... every gram of air in your intake has been accounted for, already. the excess space would lead to lag, if anything. if your O2 sensor reads that you are running lean, it increases the amount of fuel. thats what it is there for.

[mikeshoup]

fuel ratio is fuel ratio. 16 to one, compressed, is still 16 to one. It only occupies a smaller space. When cooling it, you aren't removing any oxygen molecules, nor adding any. This shouldn't be an issue unless the IC is AFTER a carburator or injector body. Then,,,, fuel will wet the walls of the IC which could / would lean out the mixture. That would be my understanding.

The Oxygen + Gasoline reaction is stoich at 14.7:1 btw.