K3-ve Engine
Milan Skidmore
It is a well known issue with the K3-VE and KE-VE2 engine that the idle control valve (ICV/IACV) either seizes or fails, leading to idle speed problems and hunting/surging revs at idle. This issue is relatively simple, the small valve which regulates the amount of air the engine needs at idle becomes seized and so the ECU cannot control the volume of air entering the engine through the bypass valve in the throttle body.
Method:
The idle control valve is part of the throttle body unit. With the bonnet open, carefully remove the intake/engine cover by pulling it upwards and easing the rubber coupling from the intake pipework.
With a 10mm socket, carefully undo the 4x 10mm bolts that hold the intake duct/air filter assembly off, carefully remove the intake temperature sensor from the rear of the air box (it pulls out) and pull the rubber hose off of the MAP sensor, bolted the the rear of the inlet duct. The sensor itself does not need to be unbolted, leave it where it is, but unplug the 3-pin multiplug that attaches to the wiring loom to give yourself better access. Then or simply swing the entire assembly through 90 degrees to make space to access the throttle body
First, carefully unplug all the multi-plug connectors. There are two - one for the throttle body butterfly valve which is black, and one for the idle control valve which is grey. These are on very short wiring harnesses so move them aside the best you can.
Next, turn the sprung black plastic arm that the throttle cable routes through to the fully open position. The throttle cable has a cast metal cylinder on the end of it that locates into a hole in the plastic arm. with the tension off the cable, the cylinder should slide out of the locating hole and you can gently release the arm again. Undo the two 12mm bolts that hold the throttle cable into the arm of the throttle body and slide it out, setting it to one side.
The ICV part of the throttle body assembly is the bit closest to the camera in this pic- it has 2x coolant pipes attached and is held on with 4x bolts with Phillips/crossthread heads. You need to undo these. I found it MUCH easier to do this by clamping the flange of the throttle body that the 2x 12mm bolts go through into a bench vice but its probably possible to hold down firmly with one hand and undo the bolts with the other hand. Be aware these are threadlocked in place so you need a fair bit of force to make them release their grip.
With the 4 bolts removed, the ICV hosing will lift off. Depending how long its been there, it can be a bit sticky, so a gentle tap with a rubber mallet or wooden object can help free it off. Be aware that coolant runs through the ICV so a small amount will have leaked out by this point. Its nothing to worry about.
You need to undo these 2x screws, its easier with the ICV attached to the throttle body as you have more to grip. The stepper motor is the black thing with 3 pins here, and is what controls the valve within the housing and is held on with 2x TS25 torx screws. These are not very tight, but please do not try and improvise with a blade screwdriver - you will just chew up the head of the screws.
What you may find is that the valve is seized in position, gentle twisting of the spindle cylinder may free it off, and application of aerosol penetrating oil like RP-90 or PlusGas will help to free off the seized valve. Keep twisting the spindle to rotate the valve through 360 degrees as much as you can to clear off any muck thats is causing it to seize up.
In my case, it made sense to just replace the unit. Helpfully, the new ICV from AliExpress comes with a new gasket. I gave this a light coat of silicone grease and fitted it to the recess in the throttle body
placed the rubber gasket in situ, the refitted the 4x phillips/crosshead bolts which I had applied grease to the threads. tighten them up slowly in a X pattern to make sure of even clamping pressure. If you are just unseizing the existing ICV I would suggest replacing the gasket as a matter of course, and using fine grade wet 'n dry paper to gently clean the mating faces of the throttle body and ICV housing.
With this refitted, I took the time to clear the general accumulated muck from the barrel of the throttle body using Autosol metal polish and an old rag. It takes a while to do, but the end result is very pleasing
As you can see, the barrel polishes up very well, as does the throttle butterfly. This ought to help airflow through the throttle body, but also prevent the butterfly from becoming gummed up with crankcase breather muck and getting gummy.
With this done you can then refit everything. First, bolt the throttle body back down with 2x 12mm bolts and 1x 10mm bolt. Then reconnect the throttle cable by twisting the sprung arm to fully open position and clip the cylindrical end of the throttle cable into the hole in the black plastic arm. Lay the cable carefully unto the groove and carefully release the arm back its fully closed position. Using a 12mm open-ended spanner, retighten the cable through the arm to allow the cable to move through its sheath correctly.
Next, refit the air intake ducting, and screw down the 4x 10mm bolts that hold it into position. Connect the intake manifold vacuum pipe to the MAP sensor, and reconnect the MAP sensor multi-plug. Refit the intake air temperature sensor (if you removed it earlier) and then finally refit the engine cover/intake duct.
Hello - thank you so much for this detailed step-by-step, it is the most useful DIY help on the topic in all of the internet. May I ask a question about process of putting the throttle body back in? I have YRV 2001, it was going very well, except the idling was not responding to the cold start or under load, when cold started or AC on and in Automatic gear - the engine shook threatening to cut out. But once warm and no AC, it was going fine idling about 700 at stops. I figured the ICV was not working so went to clean it as per this instruction. It went smoothly thanks to this post, and the ICV cylinder was not turning with so much sooty stuff, freed and cleaned. But when I put the throttle body back together - the car now stalls, hardly keeps idle - and exhaust rich with black soot coughing up. So I got a new ICV unit from Aliexpress and replaced it - but it is doing the same, possibly worse. I am pretty sure I put everything back together on the body and the air cleaner assembly OK - but what I am not sure is if I reinserted the body back on manifold correctly - and there may be leak there? Second time, I felt the body was not seating flat with a tiny wobble, before the bolts were tightened. I see in the picture the O-ring is seated inside the lower barrel. Is there anything I should watch out, before reseating the throttle body? Or is there anything else that would cause the non idle and rich mix, that I may have caused ? Any pointers will be appreciated.
With the OBD scanner plugged in, do you have the key in and ignition on, in position 2 (i.e. the position before the starter engages)? This is the most likely issue. I have an OBD scanner which connects fine to my Sirion M101 which will have an identical OBD setup to your YRV, but it will only talk to the car when the ignition is switched on.
The Daihatsu K3 engine is a series of 1.3 L 4-cylinder DOHC 16-valve, water-cooled gasoline engine developed and produced by Daihatsu since April 2000, replacing Daihatsu HC engine. This engine also known as Toyota 2SZ-FE engine. The stroked up version of this engine is called 3SZ-VE engine (1.5 L) and stroked down version is called KJ-VET engine (1.0 L).
The Daihatsu KJ-VET engine is a turbocharged 1.0 L 4-cylinder DOHC 16-valve, water-cooled gasoline engine developed and produced by Daihatsu. This short lived engine only available for Daihatsu Boon X4. This engine is a stroked down version of K3-VET engine.
It appears the bore of both engines is the same, and the 1500cc has more stroke. Toyota with their other engines tend to alter the squish area by using a different cylinder head and/or different head gasket thickness. (example the 4a-fe vs the 7a-fe).
K3-VE2 has the higher compression of the K3 motors due to flat top pistons, the K3VE pistons have a bit of a dis in them, not sure about if the head will give better compression but can say that the 3SZ head has bigger ports and flows better than the K3 heads.
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Looking from the top there isn't any sign of a leak, underneath however there is a lot of oil all over the front of the sump, but I can't tell if the sump gasket is the cause of the leak or if it is coming from slightly further up. I have photos if they would help anyone.
The Myvi is a licence produced version of the Daihatsu Sirion. A version of the KV-3E engine was used in the first and second generation Yaris, but Daihatsu continued to develop this engine whilst Toyota moved to the 1NR-FE from approx 2008. There will be differences between the Daihatsu KV-3E and the Toyota equivalent, but not sure what these differences are.
I'm currently tackling a blown head gasket on my Extol, and was wondering if I might just as well try and pick up a 1500cc 3SZ-VE engine to replace the 1300cc K3-VE. I did toy with the idea of a K3-VET for a while, but they're a bit pricey and there isn't a lot of room between the engine and cross member for the turbo. From what I can gather, the 1500 is pretty much identical, apart from being about 2cm taller. Has anyone else tried swapping these engines? How interchangeable are the ancillaries and wiring, etc.?
Sounds like a good option, but where does the extra 16bhp come from? Because the engine lays flat under the seats, I'd probably have to use both of the original manifolds anyway. Unless the K3-VE2 has greatly improved internals, there might not be any power gain. And, as some might say, there ain't no substitute for cubic inches.
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