Does dumping more fuel at low RPMs increase torque? I'm really curious about this? I heard this today and wanted to confirm this. When tuning, will this add torque at low RPMs?

Also, My friend told me he had his mechanic open up the motor and somehow with a modification he added more fuel to the engine, a LOT of fuel, since he fouled up the O2 sensor. What modification could this have been?

 

Boring the crap out of the pistons.

Aside from that, something that would drastically decrease the longevity of your engine.

 

He said something about the coils, but I couldn't figure it out. I know he hasn't bore the piston yet.

 

http://www.powerenterpriseusa.net/pr...ata/2AZ-FE.pdf

This is the "suggested base tune" for the camcon, to be adjusted by dyno time.

It suggests an increase in fuel under 4k would improve torque... but obviously, the only way to find out is to stick her on rollers.

 

I will try to add fuel by using the e-manage Ultimate. But how much on the rich side shoueld it be..?...

 

Also, fuel injectors are either "ON" or "OFF". The size of the injection hole and pressures generated judge how much fuel flow through in the fraction of a second duration it's open.

The ECU controls how much fuel goes into the motor by controlling that timeframe. This is why injectors need to be changed in turbocharged applications.... to supply enough fuel, the injector would have to stay open for an unsafe amount of time. That is deemed "maxed out."

The mechanic can't add more fuel to the motor in the manner you described unless he changed the fuel injectors without altering the ECU. If the ecu thinks it's running stock (something like 375 ?) and it's actually running 550's, then it's dumping in 40% more fuel per same "OPEN/CLOSE" timeframe.

 

According to the graph, I wouldn't go richer than 3% without dyno time.

Too much, and you'll start to gum stuff up. Valves, injectors, sensors, cat (if any)... not to mention stink like hell from the tailpipe

 

That's what I wondered, but thing is, he got to foul up the 02 sensor and I don't think he has any engine management. That's the thing... hmmm

 

Noworry my tuning will be done at the dyno, with a wideband and an EGT gauge.

 

To clarify, you dont bore pistons, you bore cylinders.

Regardless of application, adding fuel and its effects will depend on all of the other variables present (rpm, airflow, load, etc). At low rpm, non WOT (closed loop) the ECU is going to attempt to compensate for any changes in fuel addition.

The amount of fuel added depends on the pulse width of the injector. At a certain point, you max out the injector and cannot add any more fuel without increasing injector size.