cmb2020
Member Since: 08 Sep 2020
Location: Buckley, North Wales
Posts: 1150
  
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Harry365 wrote:I fitted a variable resistor in line with temp sensor cos im cheap and didnt want to pay the £40+ for a remote start. I can manually turn the temp down to whatever. I suppose downside is I have to have the engine running but not really an issue as I like my heated seats on too 8)
How did you do this please as I’m broke and would prefer to do a cheap alternative for the heater remote tia
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 15th Dec 2020 5:16 pm |
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Hardware
Member Since: 28 Jun 2016
Location: Hiding under the M60
Posts: 12722
 
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IIRC you need > 1/4 tank of fuel and >11.5 volts for it to start as a pre-heater. .
Dean
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2011 D4 XS - OBD port protection, RLD spare wheel protector, All LED interiors lights, Timed Climate enabled, iiD tool paired.
2011 D4 Landmark - Stolen from same dealer before I paid for it
2011 D4 GS - Stolen whilst at dealer  ... All LED interiors lights, DRLs, Spare Wheel protector.
1996 300Tdi - Eaten by tin worms
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| 15th Dec 2020 5:39 pm |
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Harry365
Member Since: 25 Aug 2018
Location: Lincoln
Posts: 373
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cmb2020 wrote:Harry365 wrote:I fitted a variable resistor in line with temp sensor cos im cheap and didnt want to pay the £40+ for a remote start. I can manually turn the temp down to whatever. I suppose downside is I have to have the engine running but not really an issue as I like my heated seats on too 8)
How did you do this please as I’m broke and would prefer to do a cheap alternative for the heater remote tia
It's simple.
Multitest, 2k variable resistor (pot), wire and connectors. A 5k pot will do but you have to turn it much slower and never more than a 3rd.
You need to fit it inline with the cars sensor. Cut one of the cables running to the sensor, run a new cable from there to the dash, wire up the Pot and back to sensor again. The cable length I figured lowed the displayed temp by about 0.5c
I'll take pics later
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| 16th Dec 2020 12:30 pm |
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Flack
Member Since: 06 Sep 2006
Location: Preston Lancashire
Posts: 6240
 
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I dont like the idea of a resister, when you start a very cold car and you are tricking the sensor, it will over fuel the car on startup, which in turn will do more damage to the engine by diluting the oil even more.
Thats the benefit of a pre heater it warms the water around the engine so less stress on it..
Flack 
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| 16th Dec 2020 5:20 pm |
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Harry365
Member Since: 25 Aug 2018
Location: Lincoln
Posts: 373
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I had considered this but thought of it as more of a "on paper" issue than a real world one.
I don't really think lowing from 7c to 5c would be enough to affect it, looking at perhaps a 0.25g/m3 in air density, not taking into account air pressure, humidity etc. The variables across the globe must be far greater than the difference adjusting it 2c would make. I'll admit though that the tolerances and variables are accounted for in design and adjusting it could result in stepping outside those tolerances in certain situations. Maybe just dont go crazy and leave the resistor sat at -30c when its a toasty 10c outside.
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| 16th Dec 2020 6:05 pm |
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Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10380
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Are you talking about the external air sensor ?
If yes, I doubt this is used for fuelling.
The engine ecu would use, coolant, oil, inlet air (and charge air on some models) temperature. That's more than enough for fuelling!
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| 16th Dec 2020 6:12 pm |
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Harry365
Member Since: 25 Aug 2018
Location: Lincoln
Posts: 373
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I am talking about the sensor on the bumper yes. I figure it was that one that was used as its the one used for a lot of monitoring on the IID.
It doesnt surprise me it isnt used, given how inaccurate it can be sometimes.. but i had assumed it was. Would be nice to know for sure now youve mentioned it.
I wont protect my pride if this resistor solution isn't a good idea though. Someone comes in here and tells me to get it gone and for certain good reason, then its probably gonna go.
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| 16th Dec 2020 6:24 pm |
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Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10380
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I'm sure its not an issue moving the external temp a few degrees.
I think it;s only use for:
Starting FBH, dash display/ICE warning, and disabling the air con when close to freezing
There is a lot of hysisterisis on the sensor. Way too much
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| 16th Dec 2020 6:34 pm |
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Harry365
Member Since: 25 Aug 2018
Location: Lincoln
Posts: 373
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Im fitting a 2kw cabin heater soon as the vehicle is used for camping, at which point i'll be losing the resistor regardless.
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| 16th Dec 2020 6:39 pm |
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Flack
Member Since: 06 Sep 2006
Location: Preston Lancashire
Posts: 6240
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@ Pete K Quote:Are you talking about the external air sensor ?
If yes, I doubt this is used for fuelling.
The external temp sensor is used for initial start, It is the first measurment the PCM gets before starting then the PCM works out what to set the fuel rate at and glow plugs, after starting the other sensors come in to the equation .
Flack
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| 16th Dec 2020 8:04 pm |
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cmb2020
Member Since: 08 Sep 2020
Location: Buckley, North Wales
Posts: 1150
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Hi again
Am I right in thinking this heater blows hot air in to the car on a cold start? Or does it warm the engine block up quicker?
I thought it was heat on demand, but I’m told it just heats the engine up faster instead?
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| 23rd Dec 2020 8:22 pm |
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Pete K
Member Since: 15 Jan 2016
Location: GL
Posts: 10380
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It’s primarily there to heat the engine, but it has the knock on effect of making the internal heater work quicker/better
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| 23rd Dec 2020 8:33 pm |
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cmb2020
Member Since: 08 Sep 2020
Location: Buckley, North Wales
Posts: 1150
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Ah ok thanks
Back to my original post, there’s an electric heater out there somewhere that heats the car internally with immediate effect...
I’ve tried some off eBay but they don’t work like the car I saw it in.
Does anyone know of this please?
It was in a Citroen Picasso that I saw it. (Or felt even)
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| 23rd Dec 2020 8:39 pm |
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Harry365
Member Since: 25 Aug 2018
Location: Lincoln
Posts: 373
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An electric heater is gonna need some serious power to warm the car. Talking 2kw+ no?
Are you sure what you saw wasn't a diesel air blower? You get them in a lot of campers and van conversions.
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| 23rd Dec 2020 9:24 pm |
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cmb2020
Member Since: 08 Sep 2020
Location: Buckley, North Wales
Posts: 1150
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Hi again just an update!
I’ve tried blowing in the input tube and can hear a fan spin for a second or two. But no joy on getting it warming up! On half a tank, between 0-3 degrees, and fuse is in and working thing it’s a 20
What’s the next step to getting it working please?
Not only for warmth but to work around dodgy glow plugs now too haha
Also to the last reply I’m not certain but pretty sure it was electric as it was warm in seconds. It was a people carrier family car thing.
Tia
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| 31st Dec 2020 5:40 pm |
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