Member Since: 13 Oct 2014
Location: Nottingham
Posts: 1775
FBH - diagnosing problems with Webasto ThermoTop Software
Ok, so my FBH started the cold season well, but now it refuses to fire up. I get the fan, the roar, the white smoke, then it shuts down.
I have a FBH controller from DiscoStick (highly recommended if you can get one) , which has a diagnostic port, so I connected up using ThermoTop software. I can see that the heater is faulting with no start, but as it tries I can also see the flame detector value increasing in value. It seems to reach about half way, is still climbing, but the startup sequence times out before full flame establishment. I would guess it's almost there, but the startup timeout just stops it.
I don't know a lot about the WTT software, so could someone possibly suggest the next steps to try to get the FBH to run please?
Some screen grabs here:
Click image to enlarge
Click image to enlarge
Click image to enlarge
There are two rules for success,
1. Never tell everything you know.
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23rd Jan 2016 1:26 pm
VMatas
Member Since: 26 Jan 2012
Location: Rybnik
Posts: 150
Try click yellow arrows.
23rd Jan 2016 2:59 pm
aidnoakes
Member Since: 22 Nov 2014
Location: Expat near Varna
Posts: 143
I've no experience of the webasto software but only of a Fbh that didn't want to start.
Try putting some fuel cleaner in the tank and prime the Fbh before trying to start it. You'll make one hell of a smoke screen, and it will take a few attempts (at the least) but it's worth giving it a go, even if it is just to pretend your James Bond for a little bit
23rd Jan 2016 3:35 pm
Martin Site Admin and Owner
Member Since: 06 Nov 2004
Location: Hook Norton
Posts: 18531
Sounds like it is coked up and cannot sustain the flame.06 D3 SE / 15 LR D90 XS SW / 88 LR 90 Td5 / 68 BMW 2000 ti
Any issues with the site let me know!
Pull the silver air intake pipe off and when it starting up squirt some carb cleaner in to the FBH , try it few times and see if it jumps in to life.
Flack
23rd Jan 2016 5:04 pm
Madrilleno
Member Since: 13 Oct 2014
Location: Nottingham
Posts: 1775
I think you're probably right Martin. I'm just trying to avoid having to follow Robbie's tear down and clean routine until I'm out of options.There are two rules for success,
1. Never tell everything you know.
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23rd Jan 2016 5:24 pm
DiscoJake
Member Since: 23 Aug 2013
Location: Hereford
Posts: 1429
Follow flacks suggestion; few squirts of carb cleaner / brake cleaner down the intake and don't be scared by the 'pops' !
You need to burn off the excess gum and carbon, I'd advise against a prime as that tends to chuck too much fuel in and gum up more (it's only really any use if fuel hose has been disconnected and it actualy needs priming )
23rd Jan 2016 6:51 pm
Martin Site Admin and Owner
Member Since: 06 Nov 2004
Location: Hook Norton
Posts: 18531
Jake's absolutely right, priming overfuels the FBH and is ONLY for priming, not trying to coax an FBH back into life - it actually makes it worse as the FBH soots up further.06 D3 SE / 15 LR D90 XS SW / 88 LR 90 Td5 / 68 BMW 2000 ti
Any issues with the site let me know!
23rd Jan 2016 6:55 pm
Madrilleno
Member Since: 13 Oct 2014
Location: Nottingham
Posts: 1775
Halfrauds in the morning then.There are two rules for success,
1. Never tell everything you know.
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23rd Jan 2016 6:58 pm
Robbie
Member Since: 05 Feb 2006
Location: ¯\_(ツ)_/¯
Posts: 17932
It's hard to recommend spraying something down the intake, it works but sometimes the pops and bangs are a little too violent.
Other choices include:
- Forcing air down the intake
- Changing the CO2 value on TT (if you can get to that stage)
- Feeding it pure oxygen
Click image to enlarge
None of them are as effective as taking it apart and cleaning out the carbon.
Land Rover - Turning Drivers into Mechanics Since 1948
Member Since: 13 Oct 2014
Location: Nottingham
Posts: 1775
I had thought of using oxygen, and mentioned it before on another thread - I have an oxygen generator in the garage. I had also come across a description of how to change the CO2 value, but can't find the thread again; but if I remember correctly, the FBH needs to be running to change it?There are two rules for success,
1. Never tell everything you know.
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23rd Jan 2016 7:05 pm
Madrilleno
Member Since: 13 Oct 2014
Location: Nottingham
Posts: 1775
Also, I had a run through the TT software for an hour today, but didn't get beyond the basics. Is there a way to manually sequence the startup operation so that I could latch the glow plug and fan for longer?There are two rules for success,
1. Never tell everything you know.
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23rd Jan 2016 7:09 pm
Robbie
Member Since: 05 Feb 2006
Location: ¯\_(ツ)_/¯
Posts: 17932
The bit where it fails is when it kills power to the glowplug and then monitors the resistance of it to determine if there is a self-sustaining flame. A tricky thing to vary.
Land Rover - Turning Drivers into Mechanics Since 1948
Member Since: 13 Oct 2014
Location: Nottingham
Posts: 1775
I was wondering how it monitored that, I assumed a separate thermocouple - I didn't have my glasses so I couldn't see that the units were Ohms. No way to change the threshold value anywhere?There are two rules for success,
1. Never tell everything you know.
D4 gone!
D5
23rd Jan 2016 7:24 pm
Robbie
Member Since: 05 Feb 2006
Location: ¯\_(ツ)_/¯
Posts: 17932
Not that I am aware of and my assumption is that it measures a value and a profile over time - is resistance steady or increasing = lit, resistance reducing = not lit. When cold the plug has a resistance of about 0.2 ohms, so pretty low.
Land Rover - Turning Drivers into Mechanics Since 1948
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