Tech:Engine/K Series/EFI

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K series engines at one point or another did come with factory fitted EFI also known as Electronic Fuel Injection. These only ever came on the 4K and 7K engines. Both of which can be obtained if you look hard enough.


KP60 series Starlets which were delivered in America, Europe, Japan and New Zealand came with the 4K-E engine, sporting a blistering 1290cc of displacement. The EFI system consisted of very long intake runners so that the throttle body could be located further away from the exhaust manifold, which oddly sits on top of the rocker cover.


The oil cap filler neck had to be extended about ~60mm (~2 inches) or so taller to clear these runners as it is located at the rear of the engine on the 4K-E. If you get a 4K-E injection setup DONT FORGET THE ROCKER COVER otherwise you'll never get oil into it without hassle.

Fuel delivery is taken care of by some VERY tiny Nippon Denso 145cc "green top" Injectors which are top feed and low impedance 2.4 ohm. It is also worth noting that at stock fuel rail pressure and 80% duty cycle the standard 145cc 4K-E injectors would only support 92.8 horsepower at the flywheel. After that you should either try to raise fuel rail pressure or upgrade to a similar top-feed low impedance injector to suit your desired power level.

Performance wise, the 4K-E made the same peak power as the 4K-C, The difference was that the 4K-E made peak power 1000rpm quicker at 4200rpm. Compression was raised to 9.5:1 and torque output quoted from Toyota is 74 [email protected] rpm compared to the 4K-C which only made 67 [email protected] rpm.

The design itself is quite innovative but prone to some design weaknesses which should be considered before you decide to use a 4KE injection setup on an engine that will be built for big power. A 4K-E is generally fine to use up to about 90 Horsepower (measured at the flywheel) on a naturally aspirated engine. With a forced induction engine you may be able to milk another 20 horsepower out of the 4KE but the restriction lies in the exhaust half of the head, not so much inlet side on a forced induction (Turbocharged, Supercharged, Nitrous Oxide) engines.

Points to consider when building a 4K-E for bigger power

  • Injector Size. These injectors are quite small and will require upgrading to larger sizes to support increased output from the EFI setup
  • 4KE Computer (ECU) isn't reprogrammable so any major change in engine output, induction, injection etc will most surely require some form of aftermarket ECU.
  • Restriction of inlet design - Inlet at mouth is only ??mm wide.
  • Length of runners :-
  • Runners prone to "heat soak"
  • Restriction of head itself - K series heads are not renown for attaining decent flow rates.
  • Airflow meter - 4KE uses and airflow meter to show the ECU air/fuel ratios, better airflow would be found by ditching this and converting to a MAP sensor configuration.

Availability : It is common to see 4KE injection systems going on eBay for anywhere between AUS $50 - 250 depending on how complete they are and how many people have found out about the auction. Recently Australian's have discovered that many KP6x series starlets are coming to the end of their lifespan in New Zealand and I know that I personally hear of about ~10 units per year are being imported into Australia with that number steadily increasing.


Troubleshooting : After many years of searching, I am pleased to announce that rollaclub now hosts an electronic (Adobe PDF) version of the KP6x Starlet "EFI" manual on our server. This was scanned with many thanks to our friends in the USA and can be located in the Reference section of this FAQ : [Reference Section]

Not only that, but I know that some our very friendly members (the "TRD" Brothers) have recently purchased a Toyota FACTORY manual for the 4KE KP Starlets and they intend on scanning it and sharing very shortly. It covers *everything* not just the EFI system in the 4KE PDF guide above.


My knowledge of the 7K-E only extends to those delivered in Australia, I have not been informed of any 7K-E engines delivered outside of that area, if you do know of any other regions, please contact me so I can update this entry.

UPDATE : I have been in contact with a person in SRI LANKA who owns a KR42 Van with a 7KE!

I have also scanned a copy of the 7KE Manual which may be downloaded directly from here: (50.1 megabytes large)

The 7K was the final revision of the Toyota K series engine before it was dropped from production in 2002. Boasting 1800cc and plenty of torque, this was an engine designed for and destined to be used in Toyota's Commercial series mini-vans. These can be found by searching for any later model Toyota Vans whose chassis codes begin with KR4xxxxxx

Essentially the 7K block was just a revised 5K (1500cc) design with identical piston width and specs? but the 7K was "stroked" ~300cc larger overall. This meant an engine with plenty of torque (pulling power) but not intended for huge revs or racing.

There was also a 7K-C (Carburettor) version earlier on, with the main difference being crank diameter was a couple of millimeters larger in the EFI engines to handle the higher torque. Also there are some holes in the 7K-E head that don't exist in any of the other K engines.

With a bonus for people with KExx chassis id'd cars, these engines are a much more straight forward "bolt-in" option (compared with Twin cam installations) with the promise of Bigger Torque, Bigger Power and the best benefit of EFI !

The 7K-E inlet setup features a much shorter and efficient runner design than the 4K-E did.




Once again, modifying a 7K-E injection setup will require a little bit of forward thinking and planning, but at the end of the day, this setup could quite easily run forced induction with an aftermarket ECU and a well designed exhaust manifold - you would of course want to make that all "low-mounted" and heat sheilded due to the fact that the Inlet and Exhaust is all on the same side with K Series engines.

Availability : It is becoming more common to hear about them now, but mostly people steer clear of the "truck" engine :) I would love to hear from other people using 4K-E and 7KE series engines in whatever application as it interests me quite a bit. Once again, these sell on eBay for varying amounts and at one stage or another, some of our members have owned / played with a 7KE setup.

Here is a link to a PDF file of a 7K-E setup that sold on eBay, showing that there is much demand for EFI setups 7KE on eBay

Troubleshooting : I do know of someone who has access to the Toyota factory 7KE manual, and obviously being a newer engine a lot of dealerships would still have to carry it. UPDATE : We have a copy hosted now - (50.1MB in size)

Aftermarket EFI

These are available but probably easy enough to find if you know where to look. The "TRD Brothers" have one which is for sale at the moment and is controlled by a "LINK" aftermarket ECU. It is a quad (individual) Throttle body design.


It might even be easy enough to make one of these yourself if you had access to the correct skills and tools to machine one. It is an idea that I would love to explore further myself. The hardest part would be creating the intake manifold to house the injector bosses and working out some form of quad throttle body butterfly and throttle position sensor system. You would also want to investigate incorperating a MAP sensor system somehow.

This is all I can think of right now, please contact me to help correct errors or to add some information of your own.


Article by Grimwolge

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