The battery/charge warning light should by governd by the BMS. Thing is, our car was severely underperforming and leave the battery at 11.4V which way too, however the car never made any notice.

When I changed the alternator, I took off the negative pole, however that sucker crept back against the negative pole without me noticing it and holding my wrench against the negative bolt of the alternator, fried the fuse box....which I found out later....i just saw nice sparks haha.

Even though I swapped out the alternator and started the car, 12.2V and dropped slowly at idle. I suppose the LIN signal is severely limited what it communicates to the BMS. I wondered the same thing. I later found out that, ofcourse, the fuse board was fried but I always wondered why the car didn't report a "no/low charge signal".

On cars without start/stop there's no BMS, and the alternator isn't LIN-controlled, it just has a voltage regulator inside that attempts to maintain a constant output voltage of around 14.3V (at operating temp).

I think there may be a dedicated BCM input for battery voltage monitoring, from fuse 11 on battery fusebox.

Described in BCM pinout as "Input of fuse in fuse holder A on the battery (30 analogue)". Next pin is also called "Input (31 analog)" which hints at 'clean' references.

Edited 21 June21 Jun by Breezy_Pete

Got back to the car in Ely at around 9.30 last night.

Set about swapping in my new alt at about 6.30 this morning.

Back on the road homeward by 9, home just about noon.

I was persuaded by my sister not to hang around until 3pm to be there for when her 107 comes out of its MOT. Que sera, sera.

New, 140A alt (thanks for that idea @stigma ) working well, as was the A/C fortunately!

😎

The 107 passed. 😁

Just did a quick post mortem on the alternator that I fitted approx 16 months back.

As soon as the rear cover came off I could see that this was not a recent voltage regulator/ brushpack.

I must have misremembered that.

As the brushpack came away, big clumps of brush dust fell out.

Both carbon brushes were pretty short, but the outer slipring is the standout feature!

No wonder it was struggling.

Edited 24 June24 Jun by Breezy_Pete

@Breezy_Pete Ouch, that is pretty nasty. Do you have access to a lathe at all?

8 minutes ago, Graham Butcher said:

Do you have access to a lathe

No, but that's way beyond being worth trying to save.

I did refurb the car's original alt, but it's a right faff on the Valeo designs, and I wasn't very happy with the result. I did fit a new slipring assembly, which was pretty cheap, but I wouldn't bother again.

Only paid £109 delivered for this aftermarket new one.

The alt that the post-mortem pictures are of was sold on ebay as being from a car with only 50-odd thousand miles on it. In 6:6 (metric of 20:20) hindsight, I call BS!

Now that that's done, time to move up to doing your own injector cleaning/balancing and intake cleaning 😅
I payed €275 for the walnutblaster and €245 injector cleaner.
Good tool for as long as we have ICE engines. Additional costs will just be consumables .

Edited 24 June24 Jun by stigma

22 minutes ago, stigma said:

Now that that's done, time to move up to doing your own injector cleaning/balancing and intake cleaning 😅
I payed €275 for the walnutblaster and €245 injector cleaner.
Good tool for as long as we have ICE engines. Additional costs will just be consumables .

Typisch Nederlands en Duits 😆

(Typical Dutch and German thing)

Edited 24 June24 Jun by Lee01

I bought a secondhand set of injectors from a low mileage car about a year ago and had them cleaned and tested at a local specialist.

Fitted them and noticed no change at all. 😆

Walnut cleaning would probably be more useful, but fitting a younger, less worn-out turbo is the next plan.

Also probably new water pump and thermostat housing at same time.

Scheduled for August.

Between now and then I'm keen to install some voltage monitoring kit in the cabin, looking at both alternator output voltage and battery terminal voltage.

No longer trust the car's resident warning system!

I bought a set of injectors from a low mileage car. I think it had around 40k miles on them. The state of the injectors were so bad because they were so clogged with old fuel, i was unable to get them up to par with our own original injectors. Perhaps you suffered the same problem and this is exactly why i bought the machine. I need visual representation of the state of the injectors, not an assumption of good injectors.

I ended up returning them and managed to balance out our own.

The most impactful mechanical change were the valve cleaning, EVAP valve, turbo swap, oil separator on the back and chain/tensioner kit.

Currently it's doing an insane 4.7L/100km average.

Edited Thursday at 08:095 days by stigma

5 hours ago, stigma said:

Perhaps you suffered the same problem

No, they were cleaned and tested by someone I trust.

What's the average consumption at this point?

I guess the car has to burn off a whole new tank again to get back to where it was but, before that?

I mean we could talk intake/exhaust leaks, sub optimal injection, pcv valve and oil seperator all can cause raised consumtion problems ofcourse.

As it was last time we discussed this, approx 45mpg, which is 6.3L/100km I think.

I honestly don't think this is a problem for a Roomster with this engine on factory ECU software.

It did 47mpg on yesterday's journey, 120 miles/3hrs home from alternator replacement location, with A/C working hard all the way.

Not saying it's a problem, but that's 99% sure a pcv system working suboptimal or intake leak (or vacuum related in any case).

Our car has a tune on it since, if i remember correctly, 150.000km's or so.
That made the car a little less economical but a way better torque/boost curve over the rev range. It still also is fitted with the original clutch :D

Does the engine shutter a bit at idle or is the pickup from release to pressing the throttle, just nearly unnoticable hesitant (not talking about spool time).

I would love to get that car in the best health possible.
Would be intrested in getting data from VCDS!

Edited Thursday at 14:395 days by stigma

7 minutes ago, stigma said:

but that's 99% sure a pcv system working suboptimal or intake leak (or vacuum related in any case

Oil separator and the PCV valve at cylinder head end are new and the internal inlet manifold valve was cleaned out when I found it after inlet manifold removal.

That only leaves the valve that allows air entry from air filter, which is original, but works fine.

Intake leaks maybe, but all seals on intake manifold were changed when that came off, and the two between turbo and throttle body are new. Vacuum line for brake servo etc. checked carefully.

13 minutes ago, stigma said:

Does the engine shutter a bit at idle

Not at all, as I've said before it is extremely smooth and near silent at operating temp when heard from driver's seat.

14 minutes ago, stigma said:

the pickup from release to pressing the throttle, just nearly unnoticable hesitant (not talking about spool time).

Difficult to say, because I've never driven another car with this engine, in any condition.

15 minutes ago, stigma said:

I would love to get that car in the best health possible.
Would be intrested in getting data from VCDS!

Thanks, me too.

Which data?

Skoda offer these stats for Roomy with CBZB:

I would say yesterday's journey would be nearer to the combination profile of journey, so they suggest 5.7L/100km. That's without A/C use for sure, and we all know that manufacturer's data is usually unachievable by at least some margin.

Edited Thursday at 15:025 days by Breezy_Pete

Apologies, I didn't scroll far enough and picked the CBZA data.

Should have been this one; interestingly the same, exactly, for fuel efficiency.

Then i guesssssss, it would come down to weight and more drag/cw....or something as simple as fuel quality?

Can you pull up the Fabia2 cbza?

I found this on the interwebz for the fabia 2/Roomster FL:

Fabia2 FL specs
Roomster FL specs

These specs are way more in line with what i am familiar with.

The difference between de CBZA/B is electronicly limited throttlebody movement, different exhaust flange, different style of exhaust (one single piece till the resonator vs 2 piece post cat.)
Internally they are both the same SOHC engine with nearly the same hardware.
If I remember correctly, this was done so the Greenline could be offered for a very attractive prices for leasing companies (together with some more earo/body mods).

As for Data pids:
Let's start with:

IDE00021 — Engine Speed (RPM)

IDE00347-ENG102523 — Accelerator Pedal Position

IDE00348 — Throttle Valve Angle

IDE00604 — Intake Manifold Pressure (MAP)

IDE00188-ENG101818 — Charge Pressure Specified Value

IDE06211-ENG101411 — Wastegate Duty Cycle

ENG104044 — Fuel High Pressure Actual

ENG102048 — Short Term Fuel Trim (STFT)

ENG102144 — Long Term Fuel Trim (LTFT)

IDE06734 — Camshaft Adaptation Intake Bank 1

IDE00025 — Coolant Temperature

IDE00597 — Intake Air Temperature

This is a basic dataset to see if basic paramters are met/in spec.
When data like Temp sensors and throtle postition vs throttle valve angle and high fuel pressure actual are verfified, you can omit that and replace them with more key data points where you have requested vs actual:

1. IDE06734 — Camshaft Adaptation Intake Bank 1

2. Lambda Specified Value

3. Lambda Actual Value (B1S1)

4. ENG102048 — Short Term Fuel Trim (STFT)

5. ENG102144 — Long Term Fuel Trim (LTFT)

6. Tank Ventilation Valve (N80) Duty Cycle

7. Injection Time

8. IDE06211-ENG101411 — Wastegate Duty Cycle

9. Misfire Recognition Cylinder 1

10. Misfire Recognition Cylinder 2

11. Misfire Recognition Cylinder 3

12. Misfire Recognition Cylinder 4
    
    
    

Edited Thursday at 15:505 days by stigma

56 minutes ago, stigma said:

Can you pull up the Fabia2 cbza?

I don't have a downloaded facelift mk2 Fabia owner's manual, it should be towards the back of your hardcopy one, I think?

Edited Thursday at 16:465 days by Breezy_Pete

The Roomster CBZB exhaust is single pipe from cat onward.

I learnt two things this morning, one related to VCDS and the other about the fused feed I mentioned a few posts ago (engine bay fusebox fuse 11).

I had always thought that VCDS only worked when ignition was switched on or engine was running. This morning I was looking at measuring blocks of the BCM and noticed that the displayed values kept refreshing even when ignition was off. That's good to know.

The other thing was finding that the fuse 11 feed informs the 'voltage reference' as highlighted here:

I was hoping that this would correlate with the 'battery'/charging system warning light, but unfortunately it's not that simple. Removing the fuse (with engine running) doesn't trigger the warning light.

VCDS (with ignition off) show this when fuse is missing:

The 'speech bubble' from VCDS is interesting. I would think that most of the time the engine is running, the voltage at that fuse would be higher than 13.5V (for non-start/stop cars anyhow). Perhaps the speech bubble says a different specification when engine is running? I didn't think to check that earlier.

18 minutes ago, Breezy_Pete said:

I don't have a downloaded facelift mk2 Fabia owner's manual, it should be towards the back of your hardcopy one, I think?

Just ambiguous numbers without any reference on the Y axis. It might as well be 5 cow per mile

Strange; I expected the same data tables.