Long Tube Header Dyno results & Photo

[whoguy]

Richard..... the position of the O2 sensor is only on one exhaust pipe rather than at the join.

This will mean the o2 sensor will see lower readings and will run the engine rich......

Running rich may give the impression of more power/performance.

[richardholdener]

The oxygen sensor positon has no effect on the air/fuel ratio. You can run the sensor stuck in the end of the exhaust or in one individual tube, as long as each cylinder is runing the same-the readings will be identical. Not sure what you mean by lower readings or giving the impression of more power or performance. The dyno does not read impressions-it reads real numbers generated by the motor.

Originally Posted by whoguy

Richard..... the position of the O2 sensor is only on one exhaust pipe rather than at the join.

This will mean the o2 sensor will see lower readings and will run the engine rich......

Running rich may give the impression of more power/performance.

[ddongbap]

Originally Posted by richardholdener

The oxygen sensor positon has no effect on the air/fuel ratio. You can run the sensor stuck in the end of the exhaust or in one individual tube, as long as each cylinder is runing the same-the readings will be identical. Not sure what you mean by lower readings or giving the impression of more power or performance. The dyno does not read impressions-it reads real numbers generated by the motor.

Unless you're missing fuel injectors in two of the cly. jk=]

[WolfWings]

Originally Posted by ddongbap

Unless you're missing fuel injectors in two of the cly. jk=]

Not how it works. Only diesel engines and direct-injection engines have individual fuel injectors 'in' each cylinder. Most have multiple injectors to equalize the air/fuel ratio across the cylinders, but even if you have a single fuel injector fail it should cause a global drop in overall fuel available, with a minor to major additional localized drop on the closest cylinders to the fuel injector that failed. The global drop should still be picked up regardless of which exhaust runner the sensor is in.

And then there's cars that only have SPFI (one injector for the whole engine) instead of MPFI, and even among MPFI there's sequential (one spurt per cylinder timed with the intake stroke to fine-tune the air/fuel ratio beyond just flattening it across all cylinders, what all super-modern engines like our Yaris use, admitedly maximized local effect from a single failed injector), simultaneous (timed spurts from all injectors at the same time, pure air/fuel levelling across all cylinders, least impact from a failed injector), and batched/hybrid that fires injectors more often than needed (more than once per stroke), but vaguely synced with the intake cycle, usually I've seen that only on engines that also have a waste-spark ignition system or V engines to simplify the ECU logic and use a wiring harness that just Y-forks to each bank for the injectors instead of running individual control circuits for each injector.

[richardholdener]

Multiport fuel injection means there is one fuel injector per cylinder usually located in the head or intake port aimed directly at the back of the intake valve. The sequential or batch fire refers to whether the individual injector is fired or the enitire bank is fire for each cylinder. Sequential is prefered and is usually the choice at lower engine speeds where emissions are lowered, but many sequential systems revert to bacth at higher engine speeds. Regardelss, if you lose an injector in a multiport injection system, the individual cylinder will suffer-which will be registered by the oxygen sensor (usually located in the joined collector of exhaust manifold). Losing an injector can literally ruin a cylinder from detonation. The yaris has individual injectors for each cylinder-they do not spray in any other cylinder. Hope this clears things up.

Originally Posted by WolfWings

Not how it works. Only diesel engines and direct-injection engines have individual fuel injectors 'in' each cylinder. Most have multiple injectors to equalize the air/fuel ratio across the cylinders, but even if you have a single fuel injector fail it should cause a global drop in overall fuel available, with a minor to major additional localized drop on the closest cylinders to the fuel injector that failed. The global drop should still be picked up regardless of which exhaust runner the sensor is in.

And then there's cars that only have SPFI (one injector for the whole engine) instead of MPFI, and even among MPFI there's sequential (one spurt per cylinder timed with the intake stroke to fine-tune the air/fuel ratio beyond just flattening it across all cylinders, what all super-modern engines like our Yaris use, admitedly maximized local effect from a single failed injector), simultaneous (timed spurts from all injectors at the same time, pure air/fuel levelling across all cylinders, least impact from a failed injector), and batched/hybrid that fires injectors more often than needed (more than once per stroke), but vaguely synced with the intake cycle, usually I've seen that only on engines that also have a waste-spark ignition system or V engines to simplify the ECU logic and use a wiring harness that just Y-forks to each bank for the injectors instead of running individual control circuits for each injector.