Bad Fuel Consumption, Car Running Too Cold

[MrRx7s3]

Hey guys I think I have found the cause of my car running rich all the time and eating fuel, can someone please confirm this... (ps I'm running a Power FC)...

So as I take it the actual full tune comes on at 80+ degrees celcius is this correct?

Well my car is barely ever over 80, normally sits around 75, if I give it quite a fanging it gets to 82 then as soon as I drive normally again it goes back down to the 70's range, would this be the cause?

Second question, if this is the cause... would it be because my water temperature sensor is faulty? or is my car just cooling way too much (which I highly doubt) all of the cooling system is still standard, stock radiator, fan, shroud... it's even got a front mount at the front of it which should block some of the cooling so I'm stumped...

Thanks for any help in advance, thanks.

[GTSBoy]

Most likely the thermostat is stuck open.

You can check the ECU's temp sensor. It has a defined resistance at every temperature. Just look up (google) what it's supposed to be at the temperature it will idle at. Then just compare the measured resistance against what the ECU says the temperature is.

Edited December 29, 2014 by GTSBoy

[89CAL]

Nismo thermostat maybe?

At 75 degrees I dont think its in warm up mode anymore, but would probably be a good idea to sus why temp is low. Probably thermostat as suggested but.

[MrRx7s3]

Well when I go into settings and then water temp correction, 80+ is at 1.00 - 1.00 and the rest eg 50+ are higher so I'm asuming its to put more fuel and and advance timing?, probably does have a nismo thermostat, never really checked since I bought the car, will check it out tomorrow and also write down the actual figures for 50+ etc, thanks.

[XKLABA]

Most likely a Nismo thermosate, same issue I'm having ATM, the base map on my ECU start coolant multiplier from 75deg escalating as the temp gets colder on the scale, I have to change that as my car sits right on 70deg daily driving and gets upto 76-78 on the track due to the manual clutch fan starting to kick in

[paulr33]

you are correct in your analysis that the PFC will assume a base of 1.00 at 80deg water temp +

you can either diag why your water is too cold or simply edit the 50deg+ correction and match it to the 80deg setting.

just be sensible with the car when it gets to around 50deg and ensure its properly warmed up before you flog it

[XKLABA]

Is there no break points between 50 and 80 deg ?

[89CAL]

Nope. It interpolates between if im not mistaken

[MrRx7s3]

No break points between.

[MrRx7s3]

Well I'll try adjust that and just put the 50+ at 1.00 - 1.00 correction and see how that goes coz I feel silly taking a nismo thermostat out and putting in a tridon or something haha lol... if I don't notice much difference then I'll change the thermostat aswell... i did also notice that it always idled a little lower and more power when I do get it to over 80 degrees lol and always wondered why... I will let yous know how I go both with power and fuel consumption.

[GTSBoy]

Throw the Nismo thermo in the shit can where it belongs. Never could understand why anyone would want a colder thermostat. Worst bandaid EVAR!

[MrRx7s3]

Throw the Nismo thermo in the shit can where it belongs. Never could understand why anyone would want a colder thermostat. Worst bandaid EVAR!

Probably for track to have more flow? Beats me dude.

[XKLABA]

Why is this hard to understand ?

Having an engine that runs a little bit cooler is not a bad idea, especially when that coolant is running through the head keeping the combustion chamber temps down a touch

The only problem is fitting them to engines where the ECU can't be adjusted to run properly with them

[GTSBoy]

Engines run better the hotter they are, detonation notwithstanding.

[XKLABA]

Engines run better when hotter due to their tune, if your engine has been tuned to run at 85 deg with the engine temp multiplier starting at 80 deg and increasing down the colder scale then you try and run it at 70 deg then no wonder why it runs worse, set it up to run there and tune to run there and it will run there perfectly fine and further away you are from the detenation threshold, obviously you can't run an engine hard at 20deg but 70deg + would make no difference if tuned properly

[GTSBoy]

No, engines run better hotter because they reject less heat into the cooling circuit, increasing efficiency.

Ever wonder why the Neo's thermostat is 10° hotter than the old RB25?

[MrRx7s3]

Yeah I've noticed alot of the new euro cars run in the very high 90s even 100 and a few degrees, from what I know it's for better emissions or something.

[89CAL]

How about putting a nissan thermostat in?

It may be that you have a normal thermostat and its not functioning properly. Wouldnt hurt to change it out. Only have to drain the coolant, take the 3 bolts for the thermostat housing out and change it

Fresh coolant wont hurt

New thermostat should only be $30 or so. Worth doing if you dont know when it was last done

[MrRx7s3]

Yeah I'm going to be doing that... been wanting to change my coolant for a little while now... last time coolant and thermostat were changed was when I had the car imported in 2011 and got the timing belt, water pump and all that done about 30000kms ago... what coolant do you guys recommend? Atm it's got some kind of purple coolant? I think it may be royal purples coolant? From what I've checked out so far I like the look of penrites coolant... although never used it before and unsure, what do you guys use and every how often do yous change it, thanks.

[GTSBoy]

Coolant's coolant. I just use 100000 km rated Tectalloy green stuff. It's all about the corrosion inhibitors, and not leaving it in the car long enough for how good they are or how much of them are in there to become an issue.