Stanky's Car Fixing Thread - New Battery Day 25/10

[lisbon_road]

Good effort Stanky.  I've had some KYB shocks on my Astra for about ten years and 80K miles, still very good, so you should be ok with them. 

[red5]

Not running. 

[Stanky]

Just now, red5 said:

Not running. 

Pics above are with it firmly turned off for 15+ hours

[Stanky]

The blueprint O2 sensor arrived today so i fitted that in the pre-cat position tonight, i'm hopeful that the new (to me) throttle body will arrive tomorrow along with the new rear dampers.

I removed this throttle body earlier too in prep for the replacement - @red5 did the pictures suggest anything that might be awry? I didn't start the car yet until the new TB arrives so you'll have to wait for the next exciting installment of 'Stankys idle speed fiddling saga'

[red5]

All good so far chap. 

👍

[Stanky]

2 minutes ago, red5 said:

All good so far chap. 

👍

Is there anything I should be looking at with the idle control valve? from what i can see, the idea is that the air bypass for the throttle butterfly is controlled by a thermostat in the ICV housing - I think its more open the colder the coolant is?

The issue I have is that I can't see it doing anything, it will only move with the engine running and warm coolant circulating - which will only happen with the TB fully assembled when the ICV is then hidden inside its housing. I can't force it to move positions as far as i can tell? even some sort of adaptation procedure to see if it will move from the position its currently in.

I suspect that the valve is stuck in one position which is fine for starting the car, but causes it to run too rich once it has warmed up - too rich means too much air bypasses the throttle butterfly, causing the engine to compensate for extra air with more fuel? is that correct?

[red5]

Idle control valve only allows additional air to move idle speed off the base setting. It maybe that it completely controls the idle speed with that e butterfly closed, or controls it over and above a base setting- eg 500rpm. This would be set by a throttle stop adjuster type screw on the throttle body. If someone has touched this then it's possible that the idle is always too high, so the icv is always closed as the ecu tries to lower idle speed to normal levels. 

I would try blanking off the idle speed bypass circuit and seeing what the idle speed is then. Should be zero, or very low.

Second thing is throttle position sensor (TPS) adjustment. Usually a voltage reading taken with throttle shut.

 

Follow me so far?

 

[Stanky]

Right, further updates. I refitted the throttle body, cleared the fault codes relating to the o2 sensor, connected all the electrical connectors back up and started the car up. With the delphi plugged in, I got voltage and short term fuel trim readings from the front (S1) sensor which is progress.

The idle speed remained high, from stone cold it sat at 1200 rpm, rising to 1750rpm by the time the coolant had reached 90c. Once up to temperature the hunting started again, the revs jumping between 1250rpm and 1750rpm in ~3 second bursts.

I disconnected the MAP sensor with the engine running, triggering the EML on the dashboard and causing the revs to drop until the engine stalled.

Both O2 sensors were showing short term fuel trim readings, with S1 showing -20 from stone cold, slowly rising to 0, and S2 showing a fairly consistent reading of +24-26

The MAP sensor showed readings of approx 40 once up to temperature.

@red5 - regarding blanking the idle speed bypass circuit - do you mean physically blocking the air bypass to the throttle body, so the engine management HAS to open the butterfly a little or the engine stalls?

It is possible that the throttle stop has been fiddled with, though based on the paint on it, I don't believe it has.

I wound in quite a bit of slack into the throttle cable to the TB to ensure that the cable wasn't over-tight causing the throttle body butterfly to be held open.

I plan to disconnect the battery overnight in case the ECU has 'learned' the wrong settings for the throttle body - apparently this is possible? Does anyone have any ideas as to why the idle speed might be hunting so much once up to temperature? it is stable (though too high) up to 80c then once it tips over 80c the hunting begins.

Based on the data that Tubbo posted a few days ago, the O2 sensor data is now in the right range, and there are no O2 sensor related fault codes any more, not even pending ones. However - the MAP sensor readings are too low - for the K3-VE2 engine the MAP sensor reading should be between 63 and 72 kPa, when this sensor seems to only read between 32 and 40. Might the MAP sensor be duff (there are no codes for this, at all) and be underreading? As far as I'm aware its not new, but is a replacement. I have a second (old) one I could try instead and see what live data I get from it?

[red5]

The engine runs in open loop mode before it's at operating temp, before going to closed loop. Feedback from pre and post cat sensors is used to determine air fuel ratio. The engine is up to temp.

Yes, blank it if possible, if not then leave it disconnected.

[Stanky]

Thanks, I can disconnect it now while the engine is hot and see how it runs, BRB

[tommytwo]

Stanky, I had this problem with my Rover 820 and went through many of the steps you have already taken for no result.  It turned out that I had set the plug gap 6 thou below the recomended limit.  I was tearing my hair out, lots of time wasted. The idle would rise and fall in 3 second bursts.

So based on my experience, make sure your plug gaps are correct. Good luck.

Thomas.

[Stanky]

Thank you @tommytwo - I'll check the plug gaps in the morning!

Just went out to the car with it still warm, unplugged the ICV and started it up, it threw the EML immediately (quelle surprise) but the idle was still high and quickly began fluctuating between 1200 and 1800rpm again.

I didn't have the delphi plugged in this time as the laptop needs a charge.

I've unplugged the battery overnight to try and get it to unlearn the TB settings, I'll check the plug gaps tomorrow - I have found this info on a similar (but not the same) daihatsu 1.3 here https://www.daihatsu-drivers.uk/node/16053

Suggesting:

"Or there is a inlet air leak somewhere introducing too much air at idle. This could be from the throttle body air bypass that controls the idle for auto choke air.

This could be from the throttle body auto choke mechansim sticking open. As soon as engine starts to warm up, if the choke does not close of airflow, the hunting at idle starts.

The speed changing with heater on, this is due to the extra load on alterator, so it affects engine speed.

I presume there are water pipes running through the throttle body? Take off the main air inlet pipe so you can see the throttle body butterfly flap. In front of it somewhere hopefully there should be a small air bypass hole. Stick your finger over this with engine running, to see if it lowers idle speed and stops the hunting."

I need to get the inlet ducting stuff off to be able to get my grubby digit to close the TB air bypass and see what it does while running. I can also try the old throttle body in case this replacement one has a problem with the ICV.

[Stanky]

further diagnostics fun* from just now.

I swapped over the MAP sensors to see if I got readings from the old one, it seems to be working fine as it gave me the same reading range of between 31 and 34 kPa, slowly decreasing with engine temp. The readings are at the lower end of the acceptable range according to the technical data that @Tubbo provided, but both sensors do seem to function correctly.

The O2 sensors seem to be OK too - the S1 (precat) sensor gives a voltage reading of 0.455 from stone cold, with a short term fuel trim of -10.2. By the time the coolant temp is above 75c the voltage remains at 0.455v and the STFT reading has decreased to -0.8. These readings are right in the middle of the acceptable range. sensor S2 moves a lot less, giving a STFT reading of between 28.1 when stone cold to 30.5 when coolant is above 75c. Both readings are fine according to the technical info Tubbo posted.

The hunting begins at exactly 75c, with revs rising to 1860 then dropping down to 1200 or so as noted previously. I put my finger over the air bypass completely and the engine stalled. I restarted it and used my finger to close the bypass hole about 75% and the idle dropped back to what I'd call 'normal'  - by ear it was probably 1000rpm and completely steady. zero hunting.

I think that this suggests the thermostatic valve in this throttle body is kaputt, overfuelling from cold until it hits 75c then spasmodically opening and closing and causing the abrupt hunting. By manually restricting the flow of air through the throttle body butterfly bypass (with a grubby finger) the idle speed significantly drops and is 100% stable. 

The (third!) throttle body should be here today I hope, I've turned it all off to cool down in advance of that hopefully arriving. If not, I will try to swap the original throttle body back on to see how that behaves. I think this one is shot. I'll see if I can buy just the idle control valve for one of these throttle bodies as a brand new unit (and a 5-lobed torx set) to see if I could replace just the faulty part. I'm not optimistic on either availability or price but we can see.

So frustratingly it looks like the replacement throttle body @Tubbo was sold is a duffer, combined with the dud S1 O2 sensor! We might just have this idle issue on the run now!

 

[Stanky]

Good news: the ICV/IAC valve is available new.

Bad news: only from Australia, at £414 + shipping.

Since I'll forget, its a Tridon TAC093 that I need.

[Stanky]

Just for the record, I'd like to say that the Chinese are a great bunch of lads and I have nothing but the utmost respect for their political and economic system.

https://www.aliexpress.com/item/4001344037804.html?spm=a2g0o.productlist.0.0.21c14feaOAf8xi&algo_pvid=f2497e81-954c-415d-a008-1c2a171a8830&algo_expid=f2497e81-954c-415d-a008-1c2a171a8830-5&btsid=2100bdcf16154638278886807ef650&ws_ab_test=searchweb0_0,searchweb201602_,searchweb201603_

£15 delivered. result.

[Stanky]

My lovely new dampers arrived earlier and I used my lunchbreak to fit them. Easy peasy, 20 minutes to do both sides.

I think we'd had our collective money's worth out of the old ones!

They were a different brand, Atec Germany? They seem to be inclined to actually compress and extend unlike the old ones...

No sign of the new to me throttle body though. maybe tomorrow...

 

[Stanky]

AAARGH!

the THIRD throttle body arrived earlier, I've just been out to fit it and run the engine. The part was a bit grubby so gave it the very lightest clean with a rag - no carb cleaner or otherwise - and fitted it in place. Started the car up and idle settled to 1200rpm, then slowly rose up to 1750-1800 rpm as the engine warmed up. then, when the coolant temp got to a bit under the halfway mark the hunting/surging started Y R U SO NORTY, CAR?

in desperation, I removed the new to me throttle body and fitted the ORIGINAL one that Tubbo had. started it up with this in situ and the engine revved to 2500rpm initially before very quickly settling back to 1800rpm, then the surging started again. Engine revving between 1200rpm and 1800rpm in 3-second bursts.

I find it very difficult to believe that three separate throttle bodies might all have defective idle control valves? With all three if I partially block the throttle body butterfly bypass duct the idle will drop down to what I think is probably about 1000rpm (I can't see because I have my finger stuck in the throttle body) and stabilise happily. As soon as the finger is removed, the idle rises then begins to surge.

for the love of god, what is wrong with this wretched beast! No fault codes at all, absolutely nada. All values tested so far have been within tolerances in Tubbo's manual for this engine. I'm just stumped now. What else can I try? My last ditch job for now is to wait for the engine to cool down and pull each of the spark plugs to see what the gaps are like. I think they should be 1mm, @Tubbo - does your YRV manual for the K3-VE2 engine show what the gaps should be? 

[Dave_Q]

Sorry not read the whole thread but have you tested / tried any temperature sensors?

If the hunting kicks in as it warms up it could mean the idle stuff is not being done right as it thinks it's still on cold/open loop?

Another thing is the TPS, does that have some sort of switch to indicate to the ECU when it's closed and it's time to do the idle shizz?

Sorry if they've already been covered.

[Stanky]

17 minutes ago, Dave_Q said:

Sorry not read the whole thread but have you tested / tried any temperature sensors?

If the hunting kicks in as it warms up it could mean the idle stuff is not being done right as it thinks it's still on cold/open loop?

Another thing is the TPS, does that have some sort of switch to indicate to the ECU when it's closed and it's time to do the idle shizz?

Sorry if they've already been covered.

Thanks, so the air intake temp sensor works fine, I get a reading from it which about matches what I expect (about 12c here today)

TPS I can check in a bit when I am done with work, there is a reading I can get on the delphi for this. Physically, where might this live?

EDIT TO ADD - the TPS is fitted to the throttle body, so I have tried three separate ones with identical symptoms which seem unlikely. I'll still test the readings but I'm not convinced...

[Tubbo]

This is turning out to be a right bugger! I thought someone with a bit more knowledge might have got to the bottom of this but on the bright side if you had solved it too quickly it might of made me look like a complete idiot 😂

The info for the plugs is in the manual, this is my Yrv.

 

[Dave_Q]

I was thinking engine coolant temperature, and sometimes they have more than one.

The TPS may have a on/off idle switch as well as a potentiometer part so if that's the case I would check that the switch bit is working with a multimeter.

Might need a wiring diagram to see which pins are which.

[red5]

Have you got an actual manual? Check tos resistance readings as well have voltage via diag. 

Stick it on a trailer and come to Worcester. 

[red5]

Has this had the gearbox out at all? 

[GeorgeB]

Air leak on the intake side.

[Stanky]

2 hours ago, red5 said:

Have you got an actual manual? Check tos resistance readings as well have voltage via diag. 

Stick it on a trailer and come to Worcester. 

across pins 1&3 I had 2.8v with ignition on, across pins 1&2 I had 4.98v

2 hours ago, Dave_Q said:

I was thinking engine coolant temperature, and sometimes they have more than one.

The TPS may have a on/off idle switch as well as a potentiometer part so if that's the case I would check that the switch bit is working with a multimeter.

Might need a wiring diagram to see which pins are which.

Coolant temp sensor shows temps in line with gauge, not saying its right, but it is consistent. TPS gave readings as expected below.

1 hour ago, GeorgeB said:

Air leak on the intake side.

I have had it apart, tested all the hoses and replaced every gasket. Behavior was EXACTLY the same before and after this business.

 

Minor update following further fiddling. Throttle body #2 (the one it came with) was removed earlier, I took the opportunity to remove the ICV/IACV from the main unit and bath it in brake cleaner, on the basis I had 2 more throttle bodies and I still wasn't happy it was working correctly. While it was soaking, I started the car and it idled at just under 2000rpm, as evidenced by screengrabs below. Right, Throttle body #1  isn't very well then is it?

Here is the live data screenshots from idle and when using the accelerator pedal to rev the car a bit

Then with the accelerator pressed

/\ /\ /\ Idle speed up, absolute throttle position up - as expected.

I then cleaned as much as I could on TB #2 with a cotton bud and then used a screwdriver to poke in and twist the valve round. I didn't know if this was making it more open or more closed, but I knew I was making it DIFFERENT. 

I then re-fitted throttle body #2 (still keeping up?) and refitted all the hoses. I'm getting this all down to a fine art. 

With this fitted, i restarted the engine and got these results

Idle speed was lower than it was with TB #1, but still too high. This is from 'cold' - more on this below

TB #2 With accelerator pressed - absolute throttle position is up, engine speed is up - again, as expected.

Now, what is interesting* is that with throttle body #2, having poked it with a screwdriver, the 'cold' idle speed is now UP even further, sitting at 1800rpm from basically cold. I believe I poke it more open with my screwdrivering, which makes sense if now I have jammed it further open, allowing more air through the bypass at idle. This brings me back the the suggestion easier that actually it IS the ICV(s) which are busted, all all three of the bastard things have had it. I can adjust the valve manually (to a degree) by poking it further open, but the stepper motor is either knackered, or jammed on all THREE sodding throttle bodies! Nothing else was changed, so this is the only thing I can think of right now.

On the positive side, I have a brand spanking new Chinese ICV/IACV coming which should be here by next weekend, I think this is the issue with all three wretched throttle bodies, but a supposed brand new, known good ICV should* clean this up once and for all.

As per advice from @tommytwo, before all of this I removed spark plugs on cylinders 3 & 4, checked them (they were Denso K20R-U11's) and they were gapped to just over 1mm which is right in the correct range.

The output from all of this is:

Throttle body #1 - ICV stuck way open

Throttle body #2 - ICV was stuck open a way, now stuck open more, but less than #1

Throttle Body #3 - ICV stuck open a bit less than #2 but still stuck.

The ICVs should close when engine coolant temp rises, none of them do. They are all pricks. 

So, no more play until the new ICV arrives. On the assumption (hah!) it works, I will order 2 more, I believe TB's #1 and #3 are fine, other than the ICV issue. It also means I can polish at least one of them to release MOAR Whorse POwErz. But lets get the little shit to idle first, shall we?

[GeorgeB]

Try blanking the ICV so that it can't let any air in.

[Stanky]

19 minutes ago, GeorgeB said:

Try blanking the ICV so that it can't let any air in.

Doing that causes it to stall, closing the NACA duct in the barrel of the throttle body with my finger ~75% makes the idle drop to about 800-1000RPM (based on ear) - this suggests to be the ICV isn't doing a damned thing, the valve, controlled by the stepper motor should be controlling this, not my grubby finger.

[tommytwo]

Stanky, if you have only checked the plugs on cylinders 3 and 4, then it wont do any harm to check the plugs in  cylinders 1 and 2, just to rule out plug gaps. The only other thing that I can think of is that the ECU may have an idle map, which is implemeted with a switch under or close to the pedal when the throttle closes.  On early mk2 820's, with Lucas single point injection, this switch was shown on the electrical diagram.   (And easily missed)

Otherwise, I am completely stumped to come up with an actionable idea. You have done all the things that I would have tried myself.  I hope your new ICV will give you the result you need.

Best wishes. Thomas.

[GeorgeB]

20 minutes ago, Stanky said:

Doing that causes it to stall, closing the NACA duct in the barrel of the throttle body with my finger ~75% makes the idle drop to about 800-1000RPM (based on ear) - this suggests to be the ICV isn't doing a damned thing, the valve, controlled by the stepper motor should be controlling this, not my grubby finger.

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

[Stanky]

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.