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Wideband heater strategy

 
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Hyper



Joined: 23 Nov 2014
Posts: 23
Location: vodka-drinking country

PostPosted: Wed Oct 03, 2018 3:10 pm    Post subject: Wideband heater strategy Reply with quote

I just went through my 3rd LSU 4.9, and I am starting to hate bosch sensors

It seems that this one died due to condensation (yes, I have it installed as per manufacturer's recommendations) because it gave up when I was dialing in my cold starts with the car warming up and cooling down during close to freezing outside weather, so I am sure there was plenty of condensation in the exhaust compared to the summer season

I tested my wideband controller, and it uses quite primitive strategy where a timer counts once it senses operating motor voltage. It seems that the timeout is too small, and going through bosch documentation they specify NOT to start heating up the sensor before all condensation is gone. This means running the car for a longer period of time, which I don't mind at all since I don't drive it until oil warms up, so for the sake of sensor life span I can wait a little longer. I am running Autronic so I can program it to give an output which will power up the wideband relay, or just control the wideband's main ground.

I am sure the stock ECU has a sophisticated procedure for sensor heater, and I am curious to find out what it is? Does it simple times out, or uses other info like IAT/AAT/coolant or oil temps or RPM? Easiest way would be to monitor EGT and go from there, but not all cars came equipped with it from the factory, and I don't have that input either.

What is the best wideband heater strategy for longer sensor life span?
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stevieturbo



Joined: 29 Aug 2006
Posts: 1233
Location: Norn Iron

PostPosted: Wed Oct 31, 2018 4:05 pm    Post subject: Reply with quote

Of more interest...what controller are you using ?

Innovate tend to be the most unreliable in terms of killing sensors, best fix is get a different controller lol
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joe90



Joined: 19 Mar 2013
Posts: 382
Location: under the car

PostPosted: Wed Oct 31, 2018 9:57 pm    Post subject: Reply with quote

It's not a lot different from the heater on a 4 wire NB sensor.
The heater is there to get it up to temp sooner so it goes into closed loop sooner after starting.
The heater gets it up to normal temp. Normal temp is cooler than max EGT temp and you can't use the heater to cool it down.

When it gets too hot it will read lean, leaner than what it really is.


It's pretty common to blame the problem on something obscure, particularly if you don't know what caused the problem. It happens all the time in every aspect of engineering.


Why would there be more condensation in winter tan in summer?
Makes no sense at all.
The condensation comes from the burning of the fuel which has no idea what the weather is.

Maybe you can explain your logic?
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stevieturbo



Joined: 29 Aug 2006
Posts: 1233
Location: Norn Iron

PostPosted: Thu Nov 01, 2018 10:01 am    Post subject: Reply with quote

So you dont think, there will be more condensation in cold damp environments than warm ?

Seems a little odd. Do you live in a warm climate where it is never cold ?
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http://www.youtube.com/watch?v=XgWRCDtiTQ0
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joe90



Joined: 19 Mar 2013
Posts: 382
Location: under the car

PostPosted: Thu Nov 01, 2018 10:05 pm    Post subject: Reply with quote

stevieturbo wrote:
So you dont think, there will be more condensation in cold damp environments than warm ?



Condensation comes from the products of combustion.
Water.


Why would the amount of condensation change with outside temp?
Winter.......zero deg C....summer 30 deg C,
Cold start = outside temp............sustained WOT = 900+ deg C.


Realistically in a cold environment the total condensation should be a bit less than in a hot environment because the outside air will contain less water vapour.


So that will turn everything upside down?

Logic fail.
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stevieturbo



Joined: 29 Aug 2006
Posts: 1233
Location: Norn Iron

PostPosted: Fri Nov 02, 2018 1:48 am    Post subject: Reply with quote

Bizarre train of thought.

So winter sees zero deg with no changes? Lol...

Summer sees 30 or whatever with no changes?

There can easily be temp swings of 30degC here morning to midday and back again at night. There can be visible condensation on parts without even running an engine. So it is utterly absurd to say condensation only comes from combustion and nowhere else.
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9.85 @ 144.75mph
202mph standing mile
http://www.youtube.com/watch?v=XgWRCDtiTQ0
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stevieturbo



Joined: 29 Aug 2006
Posts: 1233
Location: Norn Iron

PostPosted: Fri Nov 02, 2018 1:54 am    Post subject: Reply with quote

Bizarre train of thought.

So winter sees zero deg with no changes? Lol...

Summer sees 30 or whatever with no changes?

There can easily be temp swings of 30degC here morning to midday and back again at night. There can be visible condensation on parts without even running an engine. So it is utterly absurd to say condensation only comes from combustion and nowhere else.
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9.85 @ 144.75mph
202mph standing mile
http://www.youtube.com/watch?v=XgWRCDtiTQ0
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joe90



Joined: 19 Mar 2013
Posts: 382
Location: under the car

PostPosted: Fri Nov 02, 2018 4:35 pm    Post subject: Reply with quote

Air contains about 20% oxygen and a very small % water depending on temp and RH, hotter is more, colder is less.
At zero deg C, the ammount of water vapour in the air is close to zero.
Exhaust gas with the 20% oxygen used up contains 20% oxides of H and C, roughly half and half by volume CO2 and H2O.
There's a generalisation that for every litre of fuel you burn, you make a litre of water. All of that has to flow out of the exhaust pipe.

A cold start will ALWAYS cause condensation. How can it NOT?
That's because the RH inside the pipe would otherwise exceed 100%.
That's IF you understand what relative humidity is all about.



So....back to the original problem, if the sensor has died with cold starts maybe it's the cold start enrichment that's too rich making too much soot and blocking it up.
You'll know when it comes out black.
Sooty sensors don't work at all but if you keep on running it until the soot burns off, it should start working again. Mine does.

https://www.youtube.com/watch?v=ARYba7ZJg5Y
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Hyper



Joined: 23 Nov 2014
Posts: 23
Location: vodka-drinking country

PostPosted: Sat Nov 17, 2018 1:52 pm    Post subject: Reply with quote

the controller is techedge

I do have more cold start enrichments, otherwise Autronic will not start, its not easy to dial it in
so running pig rich could in fact contribute to the problem, which is why I'd rather have the controller start heating process with a little more delay after the start

I could try using a torch on the recently deceased sensor to see if I can resurrect it
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joe90



Joined: 19 Mar 2013
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Location: under the car

PostPosted: Sun Nov 18, 2018 1:27 am    Post subject: Reply with quote

I don't see how modifying the control of the heater will fix sooting of the sensor with a badly done cold start enrichment.
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