Here's a genuine translated wiring diagram with pin-out for Crown UZS131.

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Vate

Member
This is probably the only genuine UZS131 1UZFE ECU diagram on the web...so enjoy! KDog's wiring diagram is pretty good, but there is a couple of small errors in them... there is nothing like having the original!
I have spent 2 months searching the web and it turns that that model (so I'm told) was only produced for the local Japanese market - hence no English version was ever produced! Fortunately, I have a Japanese mate in Tokyo and he obtained and translated these for me.
Be aware, although I'm not totally convinced (because it could have been me that stuffed up), but it is possible that what is considered the right hand of the motor by us (Driver's side) is actually considered the left hand side in Japan!!!
If you discover that one bank gets a richer and richer mixture, and the other side goes leaner and leaner (as mine did), then this is the sympton of that problem. You'll need to reverse the wiring to the O2 sensors and the Knock sensors to get it right i.e. left bank to right, and right to left.
If you don't do the Knock sensors, it retards the timing back to about 10 degrees BTC on full power.
If you have no Traction Control system hooked up, you need to remove the sub throttle (traction control) TPS if there is one (or at least disconnect the TPS from the loom) and then fit a 2.7k ohm resister between E2 and VTA2, another 2.7k ohm between VTA2 and VC, and a 5k ohm between E2 and VC. If you don't, you'll get fault codes 83, 84, 85 - "TCM Communication Error".
Don't be fooled as I was.... TCM is "Traction Control Module" - not "Transmission Control Module!" - Took me a month of trial and error to work this out! The reason I went to such extremes to find this code (most people just ignore it and simply don't run an engine check light) was because it is in my aeroplane, and in an aeroplane it has to be right! - You can't just pull to the side of the road. I need an engine check light to at least give me an early warning of a fault. To get rid fault code 42 "Vehicle Speed Sensor signal", I tried wiring it to the Igniter rev-counter signal and it went well until it got around 5000 rpm and it then experienced fuel cuts... not good in an aeroplane!
I made up a simple digital pulse square wave generator similar to this one:

http://www.talkingelectronics.com/html/SquareWaveOsc.html


and I tried it this afternoon constantly running at only 20 Hz, and I was able to run at full power (5000 static revs with Propellor) and got no indication of a power cut, so it obviously just needs a signal to say that the vehicle is moving i.e. doesn't need to increase the wave as the engine speed increases.

I still have a problem in that the MAF Karmen Vortex Sensor puts out a frequency that climbs to around 470 Hz at around 3/4 throttle and then reduces to around 410 Hz at full throttle. Needless to say, the mixture leans out to just above 15 to 1... a very dangerous situation.
Does anyone have any suggestions - other than try a new one? So far I've tried three different second hand units, and they all have problems, all at different rev ranges.
As you can no doubt see, the info I've given you freely above, has cost me a bundle, but I'm happy to share it so that no-one has to go through what I've gone through to date, so it would be great if you can help me?
It's not like I can just drive it down the road to get one of you expert fitters to sort it out!!!
In case you wonder, I was running a LEM5 ECU but not without the occasional problem. Hence I wanted to install a "learning" ECU for peace of mind....
Just driven myself mad trying to get it to run right!!!
Cheers,
Gavin
 

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also the MAF sensors are very prone to contamination (oiled filters are VERY BAD) and trying to clean them tends to make things worse!
 

Vate

Member
Thanks for your replies BlackUZZ31.
The mixtures across the rest of the range are not too bad.
As you'd know, the ECU trims the fuel mapping according to the O2 sensors (at least that's what I'm led to believe) and then adjusts it's memory to remember the setting... that is from just above idle, when the motor is warm, up to about 3/4 throttle. Please correct me on any of this if I'm wrong?
Due to the fault codes reoccurring, I've unfortunately had to reset the ECU each time to remove these codes and so the ECU has to start all over again.
Now that I no longer have fault codes coming up, the ECU may have a chance to correct the values and keep them there. Time will tell... That's why I'm not too worried about the mixture over that range.
I'm told the mixture above that throttle/power setting is set by what ever Toyota has programmed into the ECU, hence the only way it should be wrong is if the MAF sensor is sending the wrong signal? i.e. garbage in - garbage out... or possibly the TPS Sensor maybe? The TPS is set according to the specs and it's values are also correct to those specs, so it is unlikely to be this?
The injectors are a light purple colour and by what I've read are the standard Crown injectors? I have a fuel pressure gauge permanently mounted (being an aeroplane, I have all the bells and whistles!) and it runs at the correct specs, and the pressure increases as per the specs. (45 up to 48 by memory). I also have a wide band O2 sensor and Gauge (independent of the ECU O2 Sensor) on one exhaust bank (4 into 1), and a narrow band Gauge running off the other exhaust bank's O2 Sensor (shared with the ECU) hence this is how I know the mixture ratios.
The MAF sensor is clean and the air filter is a course hi flow gauze material used as Lycoming air filters, and I've only got it there as I suspected that the airflow may be getting disrupted by the 'pulsing' of the propeller wash, so I've used it to smooth the airflow. I normally would have thought that if the filter restricted the air, then it would have run richer, but now that you have pointed it out, - if it is restricting the air causing an aerodynamic dam, then this could explain the signal frequency dropping off at the higher revs?... You may be onto something! I'll give it a run later on when the day warms up without the filter, and see what happens. The problem with testing the engine fitted in an aeroplane is that you have to have the weather right, you have to push the plane outside, and you have to stay clear of that big rotary scythe spinning at the front... not to mention the danger of it taking off without you if you have too much power on and the rope breaks! I've seen that happen, so I use a chain and a 1/2 inch wire rope! The only advantage is that you have a 'built in' Dyno. If only it wasn't so damn dangerous!
Thanks again.
 
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Vate

Member
Thanks BlackUZZ31,

They were useful in that it made me realise that my wide band sensor unit also has a data logger in it, so when I get time, I'll work out how to use it. (Rather busy at the moment)
I finally was able to find a fine enough day and the time to run the plane up again and you were right in that the problem was the air filter was restricting the airflow and hence the frequency output from the MAF was dropping off. So that one is solved!
I still have a problem in that same power range, as the power output seems to go "flat". I think it may be the detonation sensors picking up a little extra noise from the propeller and retarding the ignition timing, but I'm not sure yet.
To check the timing at that power output, I run my timing light mounted with duct-tape along with a miniature remote camera linked into my laptop which I have in the cabin with me. It's too dangerous to do it any other way! As you can see...everything is a real hassle and a pain to do.

Thanks again for your helpful suggestions.
 
been thinking about this the last week more and more I think 20+ year old crown wiring makes me nervous, i'd be binning the stock harness and ecu and get yourself a M400 motec they come up second hand and just buy a new harness) to run it with quality tefzel wire and coil on plug it would be much more reliable and safer!
 

sideshow

Active Member
I know of two crown workshop manuals in Australia and I have one of them
and the wiring for a uzs131 is exact and no errors

one problem that causes problems is the intake pipe into the air flow meter from the air cleaner
if this is not good and straight then u have air flow meter signal issues
ive fixed 5 or 6 of these motors with poorly mounted air flow meters and custoemrs didn't believe me till i removed air cleaner and piping and car ran heaps better

I sometimes run the spd signal of an injector signal but not sure what will happen in a plane when u get injector cut after hitting high revs and backing off

im about to do a job for a Subaru engine into a gyrocopter and guy wants a speed signal into it
so i have to make a signal generator which is not to hard with 555 timer
 

Vate

Member
Thanks Sideshow,
Great information of the connection from the Air Filter to the MAF, needing to be straight. This means the airflow needs to be flowing directly into the MAF with as little as possible turbulence. I had suspected this and this is why I had the Lycoming air filter foam at the entrance to the MAF to try to 'deaden' the prop wash turbulence, but as you know this created another problem mentioned in the previous posts. Unfortunately, I obviously don't have a lot of room to play around with under the cowling to enable much of a straight pipe between the nose cone and the MAF, so I'm screwed of an easy fix in this regard. I'm currently building a voltage to frequency converter to see if I can substitute a a standard MAP Sensor from a Celica (89420-20150) for the MAF, and if this works it will give a lot more room under the cowling, and the other most important thing in an aircraft... less weight!
I didn't want to get into this, but as you bought it up... the small errors in Kdog's wiring diagram (presume that was what you were mentioning...and don't get me wrong... he's done a terrific job!) that I was talking about is pin 22 on the PD (22 pin) plug is not VC10 but NSW. VC10 is pin 1 on the PA (8 pin) plug. He rightly guessed (?) that pin 22 was the neutral switch input, but left "???" marks and never confirmed it, which makes it very difficult for someone to rely on it being correct. As you know, when wiring these things, you need to take the guess work out of the equation. In all fairness, Kdog's diagram was only produced for people to get the motor running, and I'm the exception as I'm requiring more than that.
The pin out diagrams are numbered back to front and you can tell that by looking at say for example: the 26 pin plug... No 1 should be in the large pin cluster of 4...not in the cluster of 6 - and so on. If you have the original wiring and plugs, this is easy to work out though. These are only small errors but a person can waste a lot of time trying to work it out when doing one for the first time. The other small errors don't effect anything if you are only wiring up for the engine only, so don't need to be mentioned. Don't shoot me down on this... I'm only trying to help other people to avoid the problems and frustrations I've come across.
Yes, the 555 timer does make it easy to make a signal generator (that's the link I supplied in my initial post in this topic) and in my initial trial of it attached to the SPD pin (ECO in Kdog's diagram), I was powering the timer (square wave signal generator) with a 9 volt battery - it worked well, however when I removed the 9v battery and wired it to 12v, the code 42 came up again so I can only presume the ECU didn't like the increase in voltage in the frequency signal. I've now regulated the power into the unit to 5v, but have yet to try it. It's presently raining 'cats and dogs' outside, so it is now another frustrating wait for finer weather so that I can run it again to find out!
Thanks again.
 

Vate

Member
I overlooked your comment on the SPD sensor to an injector pulse.
I had tried that, and like you suggested might happen, the engine light would come on when you shut the throttle quickly and code 42 would come up again.
This, as you suggest, was obviously the signal being lost due to the fuel cut.
I then tried the RPM signal from the ignitor, but then the fuel would cut at around 4800 rpm....not a good thing to happen in an aeroplane!
Cheers..
 

Vate

Member
I had thought of this, but at NZ$65.90 it was a bit much to experiment with and then find out it didn't work. Sounds as though you have tried it with success?
It may sound like I'm a tight-wad, but if you knew how much money I have put into this project to date, then you'd understand!
I had already built the square wave generator, so it was readily on hand.
Thanks for the suggestion though....
You were worried about the 20+ yr old wiring loom, but this doesn't worry me.
I've had the complete loom apart, and rebuilt it.
In case you're wondering, I also have a totally independent back up fuel and ignition system, but this is only a very simple basic system and intended only to get you home.... a "better than nothing" system.
 

gloverman

Well-Known Member
By learning ECU do you mean the ECUs ability to adjust the fuel mixture via feedback from the oxygen sensor?
 

Vate

Member
Yes, that and the ignition timing.
Also it's ability to continue running if it loses the signals from various sensors, even if it reverts to a limp home mode.... at least that is what I've been led to believe these ECU's are capable of.
If I've been misled, please correct me!
 

gloverman

Well-Known Member
They certainly had some degree of fuel adjustment. The earlier ones had it across a wider range.
The stock ECU has very very conservative timing maps so the likelihood of detonationon aviation fuel is very slim. The V5 do have some retard function with excessive air temps.
I can unplug the same sensors on a engine running with both a link and a stock ECU and they will pretty much both run until I get to the cam sensors. The link only has one input so loseing that results in it stopping where the stock one has two so losing one it will still run.
On the outputs I could unplug a ignition coil and most 1uz stock ECus will cut the injectors(resulting in the stopping) whereas the link will keep running. Not sure on the crown
Personally If I was doing an airplane I would be using as new as possible and doubling up. I would be wiring two so ensure the best chance of getting home. The new G4 link has a function to allow two ecus to be wired up and be switchable which was a function intended for aeromotive use.
The biggest issue I see with the stock ECU is the 20 year old ideas in the mapping. I also replace or rebuild around 20 each year ( just 1uz ones not all vehicles)
Do you think the stock unit will be able to compensate for the altitude?

I have seen a similar situation with trying to get a stock ECU to work where it was never intended. We again had a large loading factor similar to your propellar. I got it going pretty good but used technicques that I wouldnt really be recommended in a plane.

How is the idle speed control functioning with the speed signal operation all the time?
Also have you looked at the live data from the ECU to see if there are any clues there to how it is running?
 

Vate

Member
Hi Gloverman.
Many thanks for your post.
The LEM5 I had didn't have the air temp function as it was an upgrade by Link to my original LEM1.
I would have loved to have fitted a G4 but the cost was prohibitive, although if I was able to see into the future to the time and expense in trying to get this UZS131 running properly, the G4 may have been a cheaper option. I wouldn't have learn't so much though!
All tests I've done to date indicate that the motor is putting out far more power than it ever did with the LEM5.
The switchable ECU's do provide redundancy if the ECU fails, but the most likely thing to fail is the sensors. With the very basic system I have, the only things that are common is the Spark Plugs, Spark leads and Coils. Fuel is a calibrated spray of fuel (enough for a good cruise power) via two injectors (from a back up fuel pump) directly into the inlet plenum chamber, and I simply turn one of them off via a micro switch on the throttle linkage when the power is reduced. The mixture air/fuel ratio is governed by the amount of throttle opening.... pretty crude, but better than nothing.
The ignition backup is simply a couple of correctly placed sensors that sense a correctly placed extruded screw head on the crank pulley, and that fires two independent igniters that connect to the coils through a couple of relays that isolate the original igniters. Ignition timing is once again set to a good cruise setting. Once again sounds crude, but the Continentals and Lycomings don't use a spark advancing system at all. One magneto is generally held back by an impulse system which retards the timing to about 5 degrees ATDC for starting, and then they both run fully advanced, so my system is pretty much the same as far as the timing goes. The secret is to get the motor to run at the cruise power setting just the same if you switch from one system to the other. My theory is that if I were to lose a coil, there would still be enough power to at least extend my glide to a suitable landing spot, and I've only ever lost one spark plug (due to it being faulty) which made the motor run a little rough but I didn't notice any loss of power in cruise. I only noticed it as it had a slight vibration.
I don't think there would be any problem with altitude as the less dense the air gets, the less air enters the motor, so hence less fuel gets injected.
The air temp sensor (that I didn't have on the LEM5) will be an advantage as it should compensate for the air cooling with height (by memory 4 degrees per 1000'). I had the old LEM5 (although with a MAP sensor) at 11500' past Mt Cook and it didn't seem to worry it.
The idle speed unit.... that went out in 2002 when I fitted the LEM5. I have it running without it and most of the time it seems to idle just fine. I do get the odd "miss" though.
Sorry, "live data from the ECU"? You've lost me. Do you mean the diagnostic system using TE1, and TE2? Is there something else I should know?
 

gloverman

Well-Known Member
Live data is when you connect the scan tool and see the info displayed. So you see what the ECU sees like the temp sensor , AFM frequency , knock feedback etc and the outputs the ECU is making like injector duration spark advance. They are quite primative back then but often very helpful.
 

Vate

Member
Thanks Gloverman,
I don't have a scan tool, just individual instruments such as oscilloscopes, volt meters, etc., so it is very time consuming gathering all the data.
Would you recommend I look at getting one?
I vaguely remember seeing them on eBay and they were quite reasonably priced, although I do remember thinking they were only useful with the OBD-II system. It sounds like you are saying it still may be worth it for the OBD-I system also?
My brother has one in his garage in Hamilton (not far from you), but as his cost him around 10G, I don't think I'd try loaning it in case I ended up having to buy him another!
 
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