We often get asked why we do not create ignition kits that include Yaris coils. There are a few misconceptions with these COP coils that actually do not make them PRP’s coil of choice when designing kits.
Below will be a breakdown of the pro’s and con’s dealing with facts derived from the data on hand. PRP have chosen to only supply one type of coil using this information and we hope the below comprehensive breakdown explains why.
Defining the need
In the aftermarket car modifying world, car enthusiasts push for more and more performance from their engines. Be it for drag, circuit, drift, rally, grip, all the way down to street racing to get the milk from the local corner store the quickest. The more the engine is pushed with performance modifications, the more load is put on the ignition system to provide sufficient spark to combust.
Spark Breakdown
Some cars are terrific at providing sufficient spark at higher power, some are not. This could be due to many factors such as:
- Design – Coils were not all created equal, some are just not rated to handle higher power and break down when loaded past their manufactured purpose.
- Age – Often seen on older imports, a 15-20 year old coil just doesn’t perform as well as it did out of the showroom floor. This could be caused by many factors but like all electronics they have a lifespan. 15+ years of heat cycles can break down the internal components, crack enclosures and corrode wiring/connections.
Wanting to fix/replace these flaws are the only way to succeed in making more power.
Wasted Spark
Some coils fire in batch sequence, often called ‘wasted spark’ where the ECU/ Ignition Control module/Ignitor fires multiple coils or single coils with dual spark. OEM manufacturers did this for many reasons; minimise part manufacturing costs, lack of computing technology at the time of production, etc. This batch fire in turn puts twice the load on the coil(s) than compared to sequential (individually fired coils) and misfires and spark breakdown is often seen when more power is introduced. Sequential fire of individual ignition coils is ideal with combatting this but is very dependent on your ECU capabilities, be it aftermarket or OEM.
External Ignitors & Distributers
Often found on older model cars, external ignitors and distributers (often nicknamed ‘dizzys’) provide spark from a single source. Ignitors are a central box controlled by the ECU to tell coils when to spark. Dizzys use the mechanical motion of the engine timing to provide spark via spark plug leads. There are many factors in both that cause issues but the main one to note is the central point of failure to your ignition system. Replacing with individual coils with built-in ignitors is a less problematic solution and has been proven to assist in performance increases.
Genuine and Copies
Aftermarket versions of both these coils exist, some are rebranded and some a blatant rip off copies with the genuine markings of the real OEM equivalent. These coils are half the price of the real ones and are made not in Japan like they are stamped but in Taiwan or China.
Quality Example: Fake coil – Internal Short Overheating/Spark Escaping
Quality Example 2: Fake coil – Overheating/Spark Escaping
A common misconception with ‘Yaris’ coils currently is their part numbers. Toyota Denso branded ‘Yaris’ coil PN: 90919-02240 was discontinued quite some time ago. The only time you will find a genuine version of that model coil is within a 1999-2005 Toyota Yaris/Echo or some really old stock in the parts department of a rural Toyota dealership. Buying a new set with that part number is a major red flag of being fake.
Toyota has since changed PN’s and are also using BOSCH branded coils, we are yet to find out why this is the case as they both seem to test the same. The main theory is cost cutting, but sourcing them doesn’t show any savings to the consumer.
Pricing
Obviously pricing varies depending on your location and if you get a trade discount etc. Averaging suppliers’ costs we have found the Yaris coil is roughly a large Big Mac meal cheaper than the R35 coil.
Yaris:
R35:
Source: www.amayama.com
When fake copy coils are factored in, the prices halve equally for both Yaris and R35 coils. PRP refuses to supply any copy coils not only because they are slowly killing the automotive industry, but also due to their varying quality on batches cannot be depended on. As no two fake coils bench test the same from different batches, PRP would not be able to provide the extensive warranty and support they do with varying quality products.
Connectors
This is an important subject often overlooked. Spark plugs need to be replaced on interval services to keep up general maintenance of your engine. This fact means the coils need to come in and out several times in their life time. The connectors attached to the coils take the brunt of this as over time the heat cycles can cause the connectors to become brittle and break. There is no real way of preventing this, the connectors can be sourced relatively cheap so replacing them is easy enough but their design does sway towards a preferred coil.
The R35 coil, shares the same 3pin connector as the Nissan Skyline R34 coils as well as some series 2 R33 coils. This grey connector has withstood the test of time with its rugged tab and yellow pin lock making replacement a breeze if necessary. Removing this connector from the coil is just a matter of pressing the tab down and giving it a little wiggle outwards.
The Yaris coil on the other hand has a thinner slimline design, the front white pin lock is designed for a onetime use and once clicked in you’re done, no going back now! Two things that really show issues with this connector is method in which you have to use to remove the connector from the coil. The button tab to raise the locking tab is very thin and flawed as it does not raise the locking latch far enough for the connector to be free. You are forced to use a pry tool to raise it just enough to not damage anything. After a few 1000km’s on them they almost snap off instantly and require new ones.
The other issue is the seals, as they are a 4 pin coil, one pin & wire is not needed for the conversion which makes the sealed connector not-so ‘sealed’ to the elements. 99% of the kits out there just supply pins and rubber seals but no pin blank seals. This is not a deal breaker but does add to the flaw of the connector as a whole.
Stalk Design
Height of the stalk determines how far up from the spark plug the coil will sit. This height is relatively important if you have low clearances for wiring or would still like to retain your factory coil cover.
Unfortunately the Yaris coil has a fixed length that cannot be changed whereas the R35 coil stalk is completely removable and can be replaced with longer/shorter ends if necessary.
Having a removable/replacement stalk not only allows for custom heights for clearance, but also allows for easy replacement in case of damage or cracks. Yaris coils often sourced from wreckers are found to be cracked down the side of the stalks. This allows sparks to escape out of the side rendering them useless. As the R35 coils are still relatively new (~10 years old), we have not witnessed this issue ‘yet’ but the fact you can change that section causes no future worry.
Wrecker Coils: Visible hairline cracks on stalk
Bracket kits: Visible hairline cracks on stalk after prolonged use
Data
The tests say it all…. or do they? Bench tests showed both had saturation on equally large dwell times which demonstrate they are both up for the task, the R35 coil a little more so.
Conclusion
With all the above information PRP has chosen to use the better performing R35 coil not only because of the bench tests but the stalk customisation ability and superior connector design. Proof is in the pudding, there are quite a few 1000hp+ cars out there with R35 coils showing that they are up for the task!
