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Zetec Tuning Myths Busted


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As with all parts of the tuning aftermarket, there is a lot of rumour, myth, chinese whispers and general misunderstanding about how to extract power from an engine.. hopefully the below will clear up a few things.. You can replace "1.8" with "1.6" in most of the below.



Some common topics:



"Upgrading to a 2L MAF sensor"


Myth: Fitting a MAF sensor from a 2L Mondeo will increase power on a 1.8 Zetec. Common assumption is it will let more air flow through.

Fact: The MAF is a sensor designed to measure airflow through the engine. It comprises of a metal body of a particular diameter with a calibrated sensor stuck in the side of this calibrated 'pipe'. The engine control unit (ECU) is specially calibrated to understand the output of the particular MAF sensor originally fitted to the car. Changing to a different MAF sensor with a different linearisation output will confuse the ECU, effectively incorrectly fuelling the engine.

Fact: Some 115ps and 136ps engines share the same MAF part code.

Fact: No additional airflow and potential for incorrect fuelling does not lead to an increase in power.






"Upgrading to 2L fuel injectors"


Myth: Fitting fuel injectors from a 2L Mondeo to a 1.8 Zetec will increase engine power.

Fact: The factory ECU is specifically calibrated to the fuel injectors it comes with, with regards to how much they flow and how they respond. Changing to smaller or larger injectors will either lead to lean or rich conditions and transient fuel control will most likely be non-perfect, leading to increase fuel economy and a less pleasant drive

Fact: Fitting injectors that are too large has the potential to wipe out your engine due to bore wash conditions.






"Upgrading to 2L ECU"


Myth: Replacing the 1.8 ECU with one from a 2.0 will increase power.

Fact: The factory ECU is calibrated perfectly to work with the 1.8 engine. Changing the ECU will result in incorrect engine control, potentially fatal to the engine. The same applies to changing any sensors on the vehicle.






"Upgrading to a 2L Throttle Body"


Myth: Fitting a throttle body from a 2L Mondeo will increase throttle response and increase power output.

Fact: A larger throttle body will increase throttle response. The relevant definition of throttle response here is the speed at which you achieve peak airflow (and thus peak power) when you depress the throttle pedal.

Fact: The 115ps throttle body isn't what restricts the engine to this power. Fitting a larger throttle body won't increase airflow due to other restrictions on the intake tract so no additional power will be created.

Fact: Fitting the larger TB with no additional airflow will reduce throttle resolution. This means you'll reach your actual true full throttle (full power) with less throttle pedal being required than with the correct TB. This is where the common misconception comes from that it is more 'responsive'.






"Upgrading to 2L Cams"


Myth: Fitting a pair of cams from the 2L Mondeo engine to a 1.8 Zetec will give you more power.

Fact: The increase in duration and lift of the 2L cams may increase engine output by a couple of horsepower at high rpm's.

Fact: Cams are no miracle. If you've done nothing to make the engine breathe better, by changing cam profile all you are doing is shifting the power band. This comes at a cost, and for the sake of a couple of peak horsepower which you'd never notice, you're going to lose torque in the low and mid-range of your power band which ultimately will make you slower.






"Upgrading to a FSE Power Boost Valve"


Myth: Replacing the factory fuel pressure regulator with an aftermarket unit will increase engine response.

Fact: The factory ECU is calibrated to work at a certain fuel pressure and the transient fuel and spark controls that are very well calibrated are designed to work with the specific FPR that comes on the engine. Changing to a 'faster responding' fuel pressure regulator (effectively what an FSE PBV claims to do) will upset the fuelling of the car leading to a performance decrease and most likely unnecessarily-increased fuel consumption. The ECU knows how the factory FPR behaves and is calibrated to supply the correct amount of fuel under transient conditions (eg when you stamp on the throttle).






"Fitting an aftermarket chip"


Myth: Plugging in an aftermarket off-the-shelf chip/remap will increase engine power.

Fact: An aftermarket chip/remap typically alters the base fuel and spark tables that the ECU uses to control the engine. Most of these chips/remaps/modules either add fuel or advance the ignition timing of the engine. The factory calibration is already running excessively rich (to keep the catalytic converter at a relatively low temperature) so adding more fuel will gain no power (potentially a loss) and the spark angle is precisely mapped for peak torque/power so advancing will gain nothing.

Fact: A proper custom mapped chip for your particular car could gain a few horsepower, depending on modifications. An expensive option though, unless you consider say £100 per horsepower a fair price.






"Fitting an aftermarket exhaust manifold (4-2-1, 4-1)"


Myth: Replacing the factory exhaust manifold with an aftermarket tubular manifold will increase engine power.

Fact: Unless you have done drastic changes to the engine to make it flow more air, fitting a higher flower exhaust manifold will not increase engine power.

Fact: 99% of the off-the-shelf aftermarket manifolds are poorly designed and will most likely not perform as well as the OEM part.

Fact: A well designed exhaust manifold and system with the right engine modifications/spec will increase engine power.






I'll add more as I remember.... :)

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