AFR running extra rich at WOT?

[ChinoCharles]

Betty!

[eTiMaGo]

Originally Posted by ChinoCharles

Betty!

Oh I already have a bastardised intake...

but, as I mentioned in your thread, the only reason mine is not shorter is because of that breather tube, I did not want to remove that first piece of tubing... But now I might just try it

[eTiMaGo]

http://en.wikipedia.org/wiki/Air_fuel_ratio

Oh well, this explains a lot, looks like it does not only affect forced induction situations, and I guess I'll just shut up now
Now, I wonder if this rich mixture is affected by the actual engine's knock sensor, or if it is a pre-mapped setting... Time to try some higher octane fuel (less chance of knock) next time and see what happens

A stoichiometric mixture unfortunately burns very hot and can damage engine components if the engine is placed under high load at this fuel air mixture. Due to the high temperatures at this mixture, detonation of the fuel air mix shortly after maximum cylinder pressure is possible under high load (referred to as knocking or pinging). Detonation can cause serious engine damage as the uncontrolled burning of the fuel air mix can create very high pressures in the cylinder. As a consequence stoichiometric mixtures are only used under light load conditions with more fuel added for acceleration and high load condition to prevent detonation and to cool down the combustion gasses.

[punch]

wideband afr guage would work on our cars better.

[largeorangefont]

A narrow band AFR guage is useless. Get a wideband for a more accurate picture of what is going on.

Higher octane will not change your AFR. the car will run 14.7:1 in closed loop while putting around, but in WOT situations the car needs more fuel to keep EGTs down. This is a scenario where it is not practical to run the theoretical limit because you will harm the engine. This is typical in ALL cars, and more pronounced in FI applications.

Your intake could very well be contributing to this issue. While I wouldn't call just below 12:1 too rich, but it could probably be leaned out a bit safely. Generally intakes make power by leaning the car out a bit, but yours has a tight 180 degree turn right before the MAF that could be throwing things off a bit.

Ashley

[ZPIracing]

Originally Posted by largeorangefont

A narrow band AFR guage is useless. Get a wideband for a more accurate picture of what is going on.

Higher octane will not change your AFR. the car will run 14.7:1 in closed loop while putting around, but in WOT situations the car needs more fuel to keep EGTs down. This is a scenario where it is not practical to run the theoretical limit because you will harm the engine. This is typical in ALL cars, and more pronounced in FI applications.

Your intake could very well be contributing to this issue. While I wouldn't call just below 12:1 too rich, but it could probably be leaned out a bit safely. Generally intakes make power by leaning the car out a bit, but yours has a tight 180 degree turn right before the MAF that could be throwing things off a bit.

Ashley

This is very true. The stock ECU should have you running somewhere in the 12.5 range at WOT and 14.7 at part throttle. This is what we typically see out of toyota ECUS. The Rich reading on a narrow band ecu is about as useful as that one buddy who always wants to help but breaks the parts he attempts to install.

I would put the thing on a dyno with a sniffer and get a better idea. I am not sure that I would be that worried about it if all you have modded is an intake. I am confident the car is safe.

[eTiMaGo]

Originally Posted by ZPIracing

The Rich reading on a narrow band ecu is about as useful as that one buddy who always wants to help but breaks the parts he attempts to install.

Hey that sounds like me

I'm not actually sure if my meter is narrowband or wideband, it's an analog one with a range from 10 to 17, or am I barking up the wrong tree?

So, this extra cooling capacity is meant mainly as a protection against engine overheating, not knock?

Anyway thanks for the input guys, largeorangefont, I never really liked that bend in the tube there, I'll see what I can do about shortening/straightening it, probably have to get one of chinocharles' bouncing bettys or similar