Does The Ecu Temp Sensor Affect Fuel Consumption ?

[siksII]

my thermostat is probably stuffed, as i can drive for 15mins and the car will still be below 80deg.

also annoying is if the car is warm and i drive downhill for ages (fuel cut a lot of the time) water temp drops down to around 50 in no time!

ive been too lazy to replace it, but this can definetly cause worse fuel economy as its using cold enrichment for way longer than it shoud, less power too.

[Cubes]

also annoying is if the car is warm and i drive downhill for ages (fuel cut a lot of the time) water temp drops down to around 50 in no time!

Not much you can do about that.. There's a massive hill here in Adelaide (Willunga Hill) Even though driving back from Victor Harbor is 30mins odd minutes prior once you hit that hill and sit on fuel cut for a couple of minutes engine temps drop to 50odd degree's.

[siksII]

Not much you can do about that.. There's a massive hill here in Adelaide (Willunga Hill) Even though driving back from Victor Harbor is 30mins odd minutes prior once you hit that hill and sit on fuel cut for a couple of minutes engine temps drop to 50odd degree's.

So even with a good thermostat that happens!?? i would have assumed it would close and the water temp would stay approximately the same..

its really annoying, after it happens i feel like i need to to warm it up again before giving it some stick again

btw i remember a while ago i argued with you over whether fuel cut completely cuts all fuel to the engine(ie. it only pumping air) i believe you after some testing and since then i have had the same argument lots of times with new people trying to convince them!

[Cubes]

lol... Yep I remember the discussion...

The motor can't really generate much heat without fuel and combustion. As a result engine temps drop.

[Adriano]

Even with fuel cut down a long hill, the water temp shouldn't drop with a good thermostat. To do that the internals of the motor would have to get below 80deg and actually cool the water in it. When engine braking down a hill there is bugger all air going through the motor as the throttle is shut, and there is still plenty of internal friction. there has been talk of afttermarket thermostats having dramas, maybe try a new genuine one??

[Cubes]

In theory there should be bugger all internal friction as bearings float on a flim of oil; meaning no metal on metal contact as a result no/extremely little friction apart from the friction/drag of the oil.

Combustion is what creates temps within a motor.

[Munkyb0y]

my thermostat is probably stuffed, as i can drive for 15mins and the car will still be below 80deg.

also annoying is if the car is warm and i drive downhill for ages (fuel cut a lot of the time) water temp drops down to around 50 in no time!

ive been too lazy to replace it, but this can definetly cause worse fuel economy as its using cold enrichment for way longer than it shoud, less power too.

how long of a downhill are we talking about?

my car is warm after about 2kms, only a few minutes.

i'd say change ur thermostat and you should be right.

mine stays a touch under half once its warmed up. downhill or not.

Edited October 3, 2006 by Munkyb0y

[Adriano]

In theory there should be bugger all internal friction as bearings float on a flim of oil; meaning no metal on metal contact as a result no/extremely little friction apart from the friction/drag of the oil.

Combustion is what creates temps within a motor.

Sorry, although there is little/no metal on metal contact in a motor, 1/3 power goes in frictional losses, 1/3 out the exhaust and 1/3 out the crank

[Cubes]

Adriano,

Your theory doesn't play out in the real world. Rolling down a big arsed hill for almost 2 minutes at 100km/h does see my engine temps drop from 83degree's to ~50degree's.

I've had 2 new thermostats in the car, one with the old RB20DET and it was the same, and the second in the RB30DET that also does exactly the same. My sisters old VL would do exactly the same also, that too was running a genuine thermostat.

I would be curious as to how quickly a motor would warm up if it were towed with the ignition off. My guess is a very very long time.

Do remember I'm not talking about a 30second hill, Willunga hill is one big arsed hill that you travel at 100km/h down/up for a good couple of minutes.

Give it a go and you too will see.

[RB30-POWER]

thats one big mofo of a hill from the description

Edited October 3, 2006 by RB30-POWER

[Adriano]

double post

[Adriano]

I think the problem must be associated with the placement of the thermostat in the bottom radiator hose or the size of the thermostat bypass. I cant think of any car i have driven that does this, including trucks, that can be at full engine braking for long periods of time with heaps more air being pumped through the motor as they dont have throttles, with a big arse radiator, and they dont go cold

[otto]

I would be curious as to how quickly a motor would warm up if it were towed with the ignition off. My guess is a very very long time.

youve got him there cubes good point

[GreddyGo]

The thermostat can't react quick enough, hence the drop in temp's on a very large hill!!

It's only a bimetallic spring! not a fancy electronic solenoid!

Cheers

Josh

[Cubes]

I've had a boot of a play with a genuine and aftermarket (2 different brand aftermarkets) thermostats.

It was interesting to note the aftermarket thermostats opened really quickly and by a lot. The genuine however opened more slowly and progressively and its total opening amount was half of the aftermarket. Both thermostats were rated at the usual RB 76.5degree's.

The aftermarket also would shut up much quicker compared to the genuine that would take its time.

On the road the genuine held a more consistent temp where as the aftermarket would fluctuate depending on load and driving conditions, not to mention it to considerably longer for the car to warm up.

In a VL that I had both 2 new aftermarkets and a genuine in the aftermarket even though it would open considerably wider, sooner and ran the car initially a little cooler would overheat (begin creeping past half) when driving UP willunga Hill. Both new aftermarket thermostats did this. The motor had a complete powerflush with multiple flushes of my own and a bran new radiator, all shrouding new clutch fan etc. I dropped the genuine in, the car ran a little warmer but stayed on the notch before half and most importnatly it only moved 1/2 a notch compared to the aftermarket 1.5notch.

I found it strange how the higherflowing aftermarket thermostat made the car run hotter, possibly a flaw in the vl cooling system that requires the coolant to travel just that little bit slower or something.

Hope that makes sense.

[GreddyGo]

^^ If coolant does run to quickly it can't cool down properly and you will also get electrolysis which will attack welsh plugs, waterpump, thermostat houseing etc.

Cheers

Josh

[Adriano]

The thermostat can't react quick enough, hence the drop in temp's on a very large hill!!

It's only a bimetallic spring! not a fancy electronic solenoid!

??? Have you put an open thermostat into warm water? It takes about 3 seconds to close

[GreddyGo]

Yes I have, Do it all te time to diagnose at work.

But your putting a cold thermostat in hold water, so the difference in temp is large.

So it would react much quicker.

Cheers

Josh

[Cubes]

^^ If coolant does run to quickly it can't cool down properly and you will also get electrolysis which will attack welsh plugs, waterpump, thermostat houseing etc.

Cheers

Josh

Any Idea's?

[GreddyGo]

What you mean??

If your asking about whether to use aftermarket or genuine.

I would suggest genuine. If the car is overheating or running to cold with a genuine thermostat, something else is wrong in the cooling system. Changing to an aftermarket is going to hide the problem.

Cheers

Josh