Does The Ecu Temp Sensor Affect Fuel Consumption ?

[Cubes]

Sorry I should have been a little more clear..

I meant; have you any idea's why the VL may have ran hotter underload with an aftermarket thermostat that opens greater and earlier (not to mention also has a cooler general driving temp)?

As you said..

^^ 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.

I said above the aftermarket is what made the VL run cooler under general conditions but when giving it a bootfull it would run hotter, hence my guess that the coolant may have been flowing too quick through the rad/engine etc/

The genuine thermostat brought temps up quicker, ran a tad warmer but kept the temps much more consistent and it didn't get as hot when giving it a bootfull.

I have ran an aftermarket thermostat in the RB20DET but didn't like how slow it was to warm up. As with the VL it also made the motor run a tad cooler (in the 70's vs low 80's). I didn't experience any hotter running conditions though, all it did was run cooler across the board.

[Adriano]

I think this problem must be due to the position af the thermostat in the lower radiator hose. All cooling systems are setup with a thermostat bypass(usually a small hose) which keeps a small amount of coolant circulating even with the thermostat shut, with the thermostat in the lower hose, this bypass would be bigger, as the thermostat has more "heat lag" as in if the motor gets hot, it has to heat all the water in the radiator before the thermostat sees this increase and increases the flow. A bigger bypass reduces this lag. This probably explains wht skylines seem to take a bit linger than othe rcars to heat up, and why this problem seems confined to vl's and skylines.

[Tangles]

anyone got a part number they would like to share, quoted price maybe?

(for ecu temp sensor)

also, whats the recomended guidline for the general replacement time-period? For example, the O2 sensor should be changed over every 40000kms I believe.

[Adriano]

AFAIK they last forever. they dont tend to die over time like an o2 sensor, as long as coolant is used, however they can break internally or externally

[Cubes]

Mine died, I noticed the VL ran the same plug and thread so I used that. Works fine.

[siksII]

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.

AFAIK they last forever. they dont tend to die over time like an o2 sensor, as long as coolant is used, however they can break internally or externally

Im talking about around 10-15mins 100% steep downhill all the way, even with short hits of full throttle acceleration. Thats when the issue is most pronounced, but even driving around on the open road if its majority no throttle slight downhill it still cools down to the 50-60degree level, just like cubes has seen.

Adriano, i have not pulled mine out, so you could be right in that it is broken, but i reckon its just died over time, there might be some manufacturing differences which result in good and a few bad ones?

In heavy traffic mine warms up sort of quick, maybe around 8mins if its not cold outside, in light traffic (mostly light throttle too) i have driven up to 15mins and it still isnt warm.

[Cubes]

I must add Willunga hill is the only time I've seen engine temps drop. Around here its pretty flat. Slight hills but not long enough to drop engine temps.

Your thermostat definitly sounds iffy siksII. Even on 4degree mornings I start the car drive it 30seconds later and no later than 1-2minutes or ~1-2km its up to operating temp (82-84degree's). As I mentioned earlier the only time I've seen the car take longer than this to warm up was when running the aftermarket el' cheapo thermostat.

Its my oil pressure/temp that takes ages to drop/warm. I've timed ~8minutes of driving before oil pressure is normal.

[siksII]

yeah i know its dodgy, i have been very lazy lately, i cant bring myself to get out, buy one and change it

while we are on this topic, does anyone know if when cold, the power fc changes timing as well as AFR, or just AFR?

and either way with the default setting, what diffrence in AFR/degrees does it make?

i have seen there is a table in there that u can change, but cant remember the details, and i dont think i understood to what degree it changed things either.

Edited October 5, 2006 by siksII

[rb25ceffy]

Two ways you can check it.

Firstly by disconnecting the plug and using a multimeter measure the resistance across the two terminals at the different water temps.

Spec is

20deg 2.5k ohm

80deg 0.3k ohm

Second way is to measure the voltage between ecu pin 28 and earth at the different water temps.

Spec is

20deg 3V

80deg 1V

As long as the test results are somewhere close to the spec it isn't faulty.

Hope that helps.

I'm gonna raise this from the dead!

I tested the voltage coming off my engine temp sensor (for the instrument cluster, not the ecu sensor) and it's starts up at like 8Volts, is that normal?

The Gauge dosn't work and I'm trying to find out why. I drive a A31 and an rb25 has been swapped in, so far I've found a wire that was soldered together with the temp sensor wires that should not have been :S I figured that would fix it. But now it just sits at the bottom, where as it would go strait to half and not move with that wire connected.

[RB30-POWER]

Ok, what you need to do is locate the wire from the dash/temp guage that should connect to the temp sender on the engine (its a single wire)

Now, get this wire and connect it to ground/earth temporarily.

Turn on ignition and see if guage rises to full scale (HOT) - Turn the ignition off before it shoots off the scale.

If it deflects to full scale, you know the guage is working fine and you will have to get the correct sender in the engine to suit the dash guage.

So basically make sure you use the A31 original sender not the RB25 item, that would be different.

[Tangles]

anyone got a part number they would like to share, quoted price maybe?

(for ecu temp sensor)

also, whats the recomended guidline for the general replacement time-period? For example, the O2 sensor should be changed over every 40000kms I believe.

hey, anyone with a part number? Ive been searching and just cant find it.

what part number, where can you get it from?

I gather the going rate is around $50.

cheers in advance

[Cubes]

Tangles..

The ecu's water temp sensor is the 2 pin larger sensor. Its the same as the R31/VL RB30's.

Aftermarket I priced one up around $40; new nissan i believe they are around $90.

The water temp sensors are the same as the rb26 inlet temp sensors.

But do check it looks the same before ordering as you never know.

[RB30-POWER]

The RB25 sensor has different connector to the VL/R31.

Resistance seem same/similar however.

The R32 must use the older connector (squarish shape same as 26 inlet sensor as you say)

[Cubes]

Cheers.. I did check the engine manual and the R33's do run the same resistance..

Just the connector, not too much of a drama.

[Tangles]

ta ....

[SKiT_R31]

How would the engine run if you just put a 0.3kohm resister into the plug, so it never had cold richen?

what is the reason engines run rich at idle, safety (for morons who cane the car cold so they dont cook the motor? since lean burning is a hotter explosion)?

I noticed going from a clutch fan to temp controlled electric thermo made my warm ups quicker

[Cubes]

Ever driven an old carb motor without a choke?

You need the cold start enrichment; they drive like absolute cops without it.

I've leaned mine out as much as possible before I experience drivability hessitation & bogging problems.