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Stanky's fixerating of vehicles thread - (overdue) Professional help 8/7/21


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5 minutes ago, GeorgeB said:

QED. The ICV is not working. Either it's fucked or whatever controls it is fucked. (Or both.)

So thats the thing, either 3x throttle bodies have bad ICVs, or the control signal from the ECU is bust. I really, REALLY hope its the former and a new ICV sorts the issue because troubleshooting the ECU signal to the stepper motor sounds like a less-than-ideal way to spend a wet saturday afternoon.

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1 minute ago, Stanky said:

So thats the thing, either 3x throttle bodies have bad ICVs, or the control signal from the ECU is bust. I really, REALLY hope its the former and a new ICV sorts the issue because troubleshooting the ECU signal to the stepper motor sounds like a less-than-ideal way to spend a wet saturday afternoon.

It's the ECU then. Or the wiring from ECU to ICV.

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I hope you are out there getting the readings now, I want an update by early breakfast 👍😉

P. S, when you've solved your one you can have a go at the Sigma tb, icv, stepper motor, mines fkin annoying in that sometimes it will idle normal, sometimes idle 2500rpm,sometimes 1200rpm, sometimes pulsing between 800 and 1500,sometimes idles perfectly all day, sometimes dies at every junction, but when she drives she drives lovely, well she did until I think the clutch release bearing disintegrated, now she doesn't like to drive at all😪😪😪😪

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11 hours ago, red5 said:

Stanky do me a favour and get a MAP reading with ignition on and engine off please.


No problem. The map sensor reads 100kPa with ign on and engine off.

I checked the loom side pins for the icv with a multi meter, I have 12v between pins 1&2 and 2&3, but zero volts between 1&3. That suggests to me that the icv is at least getting power, and probably signal too? 

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Knowing there is good voltage across the wiring loom side of the ICV plug really makes me thing I have just been spectacularly unlucky with the 2nd hand throttle bodies.

I've ordered a set of 5-lobed torx bits which should be here in the week, what I plan to do is extract the ICV gubbinz from the throttle body to work out how it is supposed to work - its not clear to me if it is a butterfly valve (like the pain throttle body barrel) or a plunger arrangement. With this apart on the bench I can give it a really good clean up to begin with, and see if it will then unjam. Assuming that it wont at this stage, I can at least set it manually to be 3/4 closed, refit it and try running the engine then.

I watched a very interesting youtube video last evening about surging idle and it said that a lot of cars will have the ECU detect too fast an idle once up to temp and will cut power to the injectors briefly to try and bring the speed down. The ECU then fights with the ICV stepper motor, because the injectors can only have power cut to them briefly or the engine will stall, so it surges as first the injector power is cut (engine speed drops), then the ICV takes over and it revs back up to where it was before.

This figures, based on the idle speed being 1500-1800rpm up to 75c, then the surging starts once the ECU knows it can try to fight the ICV by cutting power to the injectors. I really believe the issue is three dud stepper motors, and once I have a brand new working one, the idle will sit much lower and I won't see the surging any more. While I wait for this to arrive, manually setting the position of the ICV to restrict the air flow (precisely what happens when I close the NACA duct in the throttle body barrel with my finger) will reduce idle speed and the surging, because the ECU will see the idle speed within its 'tolerance' range and stop cutting power to the injectors to try and bring it down.

@mitsisigma01 - does the Sigma have an OBD2 port? I WILL get to the bottom of this issue with the Daihatsu and am happy to put my new-found diagnostics knowledge to good use on other cars. Are you able to see the part number and manufacturer of the ICV/stepper on your car and I can check Aliexpress for replacements - its orders of magnitudes cheaper than genuine parts and probably all come from the same factory anyway. They also seem to have MAP/MAF sensors at a fraction of the price of a branded one (even aftermarket branded) too. e.g. an aftermarket MAP sensor for the Daihatsu is about £95 on ebay, or an aliexpress one is under £10. I'm happy to play parts darts when its that cheap.

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1 minute ago, mitsisigma01 said:

Obd 1 ☹️, built in Australia June 93, UK registered March 96 

Ok, poss not an issue if you can get the part numbers and we can see how expensive or otherwise some new parts are. An entire throttle body, brand spanking new is £80 delivered:


The clutch kit seems to be available, though is the thick end of £200 on ebay

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VICTORY IS MINE!!!!!111!one!11!

Nailed it. The idle speed issue is no more and my 'to do' list is now very short indeed. Today my 5-lobed torx bits arrived from ebay, I needed these because the stepper motor for the idle control valve is held onto the ICV housing with 2 torx screws, but to stop people with a LEGITIMATE INTEREST in fixing the wretched things from getting inside the blasted thing, they use 5-lobed screws. Getting hold of male versions of these is surprisingly difficult...

I had all the throttle bodies off the car at this point, I grabbed the original one that was fitted in @Tubbo's ownership and carefully undid the 4x phillips screws that hold the ICV onto the throttle body itself


with that removed, I could then carefully undo the black stepper motor from the valve spindle


Its magnetic and just popped off the end of the spindle. This was where victory was obtained. The spindle was seized solid, meaning the poor little stepper motor couldn't adjust the position of the valve to close off the airflow though the throttle body butterfly bypass. I gripped the end of the spindle betwixt my mighty thumb and index finger and twisted back and forth gently. suddenly there was a click, and it started moving. w00p w00p. I squirted some plugsgas onto the valve bit and repeated and could feel the roughness as I spun the valve 360 degrees in the ICV body, a few more rotations had it spinning cleanly, so I refitted the stepper motor to the end of the spindle, did the 5-lobed screws up again and refitted the 'troll face' gasket between ICV housing and throttle body.


With this done, I refitted the throttle body to the car, plumbed in all the hoses, bolted the air filter duct back on and started the car up. It began to idle at 1200rpm, lower than before, but still a bit high. I let it idle for a few mins then poked the accelerator pedal with my foot, the revs jumped up, then it settled back down to 1200rpm again. Previously, doing this would send it up to 1500-1600rpm so we were making progress.

I let it get up to temperature without touching the accelerator, then gave it a poke and was rewarded for my tenacity with this beautiful sight


A 900rpm idle! It sat at 900rpm perfectly, ticking away perfectly. I let it idle away for a few more minutes and tried again with the same result, revs up then settles back to 900rpm. I'm so pleased that I've managed to sort this out! When the third (!) throttle body produced identical results ot my existing two, I really did start to question whether I was chasing some terrible ECU fault or something hideous, but no, it was just plain bad luck. Three separate throttle bodies, all with identical issues - the ICV was sticking and the stepper motor couldn't produce enough torque to free the spindle.

This is a closeup (a bad one) of the actual valve


The air flows in the top port, and there is a spindle with a blanking plate section that opens and closes the gap to let air through to the bottom port and into the inlet manifold. as the valve couldn't move, the idle speed was stuck because the flow of air couldn't be regulated. I'm surprised this didn't trigger an EML or something, but anyway. Its now fixed, the idle is spot on where it needs to be and I have two spare throttle bodies and will soon receive a new ICV from my mates in the PRC.....

...leading me to phase 2. With a new ICV, I decided to give one of the spare throttle bodies a polish up. Before:


A bit grotty, wouldn't you say?

After a seeing to with autosol and an old t-shirt


It needs more work, I plan to buy myself a dremel and give it a really thorough polishing to make it as smooth as possible and see what difference (if any) it makes. Shiny things can only help, right?

This leaves just two things. Welding and tyres. With the idle issue sorted I will probably buy a set of 4 new tyres for it as I know the welding - while awkward - is possible and then we can get it down to the MOT station and back on the road, hopefully by the summer.

I am literally elated!


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  • Stanky changed the title to Stanky's fixerating of vehicles thread - Idle speed issue megafixed 18/03

Absolutely superb news! If only the second hand throttle body I bought was working properly, it would have been a 10 minute fix for me, but Sod’s law and all that.

I’m really chuffed for you and glad to see that this little beauty will be back on the road again once more!

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Nice one Stanky! TBH I'm not that surprised you had three duff ones. It's obviously a common problem on your car and is on many others too.

It's great to see that it's now defo worth rescuing and putting a little money into. 

Is there much of a market for rebuilt units, now that you have spares, the knowledge and specialist tools?

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8 minutes ago, spartacus said:

Nice one Stanky! TBH I'm not that surprised you had three duff ones. It's obviously a common problem on your car and is on many others too.

It's great to see that it's now defo worth rescuing and putting a little money into. 

Is there much of a market for rebuilt units, now that you have spares, the knowledge and specialist tools?

Thanks, I'm just amazed, with TB #3 I was sure it was more serious than first thought!

Re the rebuilt units, its certainly something I'm considering. The Rally II cars are rare, as @Tubbohas said there are only 30 on the road in the UK, but the throttle body is shared with the regular Sirion 1.3, the YRV, Terios and the Toyota Yaris (plus potentially others) so its certainly something I can do. Now I know what I'm doing (hah!) its a 20 minute job to free up a bad ICV, replacement outright would be even quicker, but cost a bit more as I'd need a new gasket and ICV, but we're only talking about £25 in parts.

I'm happy to sort this for any other shiters who have similar symptoms though. 

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21 minutes ago, GeorgeB said:

Well done.

Did you add some lubricant after cleaning with penetrating fluid? Might be worth it.

For now, no. I intend to do a thorough overhaul of the partially polished one and use that instead. That will be getting a brand new ICV but I will carefully grease the spindle with a cotton bud to give it the maximum service life when i fit it.

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A hero walks among us, where he treads rust is cast asunder; in his wake, cats are drawn inexorably to his competence. (The book of Malcolm, chapter 3 verse 61 - 93. Old Shite version)

Today, master welder and fabricator extraordinaire @Talbot of this parish came over to assist with the dubious metalwork of the Daihatsu. Not only is his a gentleman of distinction, he's also a dab hand with the grinder and MIG welder. While I plied him with thin tea and pork products, he cut away the rusty grot on the car and expertly let in lovely shiny new metal bits. From earlier in the threa,d you may fondly recall such popular hits as "the passenger side rear inner arch" which formerly looked like this


Then this


then THIS


But now, THIS!


grot chopped out, new metal let in, ground back, and zinc primered in anticipation of a coat of either black enamel or bitumen paint shortly. BUT THATS NOT ALL

We also spotted a nasty bit of rust in the passenger side seatbelt mount, which was cut out and a new fillet welded in.


We then turned the car around (more on this later) and he attacked the deeply dubious drivers side chassis rail. The concern here was that it looked mega crusty, mega close to the spring mounting. It looks like we caught it just in time, and cut back to bright metal  without needing to lop the spring mount off



There's some surface rust, but nothing a liberal dose of vactan and dynax wax won't sort out once this has had new metal let in. Sadly, bad light stopped play for today, but we got about 75% of the work done today. Next up is fabricating new metal for the drivers side chassis rail, and treating a couple of nasty looking, but superficial grot spots on the inside of the boot


Hopefully, these will be dispatched late next week/weekend and I can then reassemble the interior, and get a set of tyres ordered to replaced the aged current set - then its escalate to defcon 4 and book it in for a test. We'll have sorted all the major defects from the last test, and I'm reasonably confident of a pass with just advisories for a few bits thing time round.

What I did notice while turning the car around was that the ICV I hastily reassembed a week ago has stuck open again and the idle is up again. I have a very well lubricated spare, but what will be easier to deal with I hope is the AliExpress one which should* arrive here during the week this coming week. I can fit that to the polished throttle body and hopefully it will behave for the MOT.

I also need to sort some insurance for it as well. But mega progress has been made today, and I'd still be in a massive bind were it not for the skills, patience and kind offer of assistance from another shiter (one far more talented than i will ever be!)



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Just ordered 4 Toyo Proxes CF2 tyres for it as well, I went up a smidge from the 175/55r15s to 175/60r15s as there was a wider range of rubber available and at much better prices. I'll get them fitted in the week I hope.

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This is a really good thread Stanky thanks for sharing.  Impressed with your tenacity, all helps us with our own jobs.  Still want to try my OBD1 Astra on your software sometime to see if we can get a response, when we're allowed to (especially as there's no rush and it is in bits).

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1 minute ago, lisbon_road said:

This is a really good thread Stanky thanks for sharing.  Impressed with your tenacity, all helps us with our own jobs.  Still want to try my OBD1 Astra on your software sometime to see if we can get a response, when we're allowed to (especially as there's no rush and it is in bits).

No problem at all @lisbon_road - now I know my way about the diagnostics a bit more I'm more than happy to help! I'm confident it will talk to the car, even if the data readouts are limited. Offer goes for anyone else too, if I can help anyone with car diagnostics/setting all the airbags off and you're in the general area then please give me a shout. I can bring it along to meetups too when we're allowed to do those again.

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  • Stanky changed the title to Stanky's fixerating of vehicles thread - Megawelding with someone actually competent 21/3

It will read out fault codes through the standard available Opcom software, but there's no live data and you know that live data is everything. 

As to airbags, I have let one off in the garden once.  I read that I wasn't allowed to throw them in the scrap without letting them off, so I connected it up to some very long wires and sat with the children at a suitable distance and applied 12 volts.  There was an almightly bang and the thing that surprised me was the smell of explosives. 

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The brand new ICV arrived earlier, with a bonus of having a brand new gasket too. Thats <9 days from the PRC to Hampshire for £15.50 which is ruddy impressive.

Fitted to my polished throttle body tonight and will replace the unit in the car tomorrow


Seriously impressed with that service. I'll likely order another as a spare for the throttle body I'll be removing tomorrow.

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New throttle body fitted this morning - the polished one with new icv. Plumbed it all back in and rebuilt the intake stuff.

@Talbot spent the day completing the welding, rebuilding the drivers side chassis section in the rear arch, as well as the seatbelt mounting plate and some of the inside of the wheel arch inside the boot. We got zinc primer on it and I'll add enamel paint over the top of the zinc primer tomorrow. 

Then I can rebuild the interior, it needs the rear seats refitting, the boot covers and other bits

I also managed to get two of the Toyo tyres fitted to the wheels and will take the others to the tyre fitter tomorrow.

Then it's basically ready to be booked in for it's MOT. Everything it failed on last time has been fixed, and lots more besides. It should be ok I hope!

Watch this space for further updates




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As expected, the hole in the offside rear chassis rail was nice and small* had easy* access and just needed a tiny* patch*



Actually, access wasn't the worst I've dealt with by a long shot.   Did the repair in two sections, welding the bottom of the rail in first, then the vertical afterwards as it meant I could put one of the welds inside the box section, which was definitely easier


we were also quite lucky that the corrosion only just went past the spring mounting.  It was possible to bash out all the jacking corrosion above it and then weld the plate in over the top of the mount, running another weld internally in the box section.  I was very much trying to avoid removing the spring mount.

The rot in this seems to be mainly in the seams.  There's very little surface corrosion anywhere, but it's fair share of swolen seams with jacking corrosion in (although far fewer now...)

"Jacking" so named as it jacks the adjacent sheets of steel apart with some quite remarkable force: https://en.wikipedia.org/wiki/Oxide_jacking


That's two layers of steel about 0.8/0.9mm thick with about 4mm of black oxide between them, hence the overall thickness.

It's also remarkably localised, as cutting just another 10mm or so off that rail, and it looked like this:


Which has all-but none.  The slight gap between the sheets being filled with burr-over material from the cut.

All in all, some pleasing repairs to a very funky little car.  Just hope the MOT man doesn't poke any more holes in it.

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Interior fully re-assembled this morning, I put some carpet offcut under the spare wheel (between metal rim and metal boot floor) to prevent it rubbing through the paint again. The rear seat back bolted back in happily, but I managed to mangle one of the clips that secures the leading edge of the squab to the floor - is this likely to be an MOT concern? I ended up pulling it out with pliers and just pushing the U-shaped metal thing into the recess in the floor for now. Its held in on the other side fine.

I refitted the boot liners and applied some Toolstation matt black 'Industrial' paint over the external zinc primer for now.

I also managed to get the other two tyres fitted to the wheels, the wheels back on the car and down off of the lift again. I drove up and down the drive a few times to make sure the new ICV worked correctly (it did, idle was initially a bit high but settled down perfectly once warm) and also to scrub off the accumulated surface rust from the front discs.


The tyres fit the arches fine, despite going up from 175/55r15 to 175/60r15s as there was lot more choice in the tyre options in this size, and there were a shitload cheaper - 4x Toyo Proxes CF2s were £40 each on Camskill vs £75 odd per tyre for something I'd heard of in the 55-sidewall size. You could probably go up to 175/65r15s to be honest.

I'm not sure what the last MOT place meant by the 'little reserve travel' on the brake pedal, the feel is very good IMHO and it'll trigger the ABS no problem when slamming the brakes on? 

I've booked it in for an MOT next Thursday at my local place who have proven themselves to be entirely fair in my experience. I'll day-insure it for now in case they make a fuss, but I've also got a reasonable quote for a 5,000 mile per year policy on the basis it passes. If it does go through, I'll get some Dynax S-50 wax for the cavities to give it the best chance of survival in the medium term. I've held off on buying this in case it gets picked up for more welding, as S-50 is flammable so I want to do this once all is ship-shape.

Tax is a tenner a month which is fair. 

Some pics of it out in the wild from earlier



I cleaned up the headlight lenses with the last of my QuiXX resto kit, and I also linseed-oiled the grille, plastics between the front fog lights and scuttle area to make them black again rather than sun-faded grey.

next stop - MOT!


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  • Stanky changed the title to Stanky's fixerating of vehicles thread - (overdue) Professional help 8/7/21

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