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Cold Start - Can It Be Removed?

WazR32GTSt
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WazR32GTSt Grand Master

WazR32GTSt

Posted
Posted (edited)

Can anyone tell me the function of the extra-rich cold start?

i mean, my car idles crap and drives jerky (liek most r32's) when its cold, but is much better when its warm..

so i have been thinking...

what if i wire up the coolant temp circuit so that it always thinks its 'hot' and always gives me a nice idle?

is this bad for the engine in any way?

this is what i got from the rb20 workshop manual:

Cooltan temp sensor controls

- timing

- idle

At cold temperatures (20deg), the sensor gives the followign readings

- approx 3 volts

- 2.5 k ohms

At warm temperatures (80deg), the sensor gives

- approx 1 volt

- 0.3 k ohms

So... if i get a resistor that is 0.3 k ohms, cut the temp sensor off, and wire this resistor into the circuit so that it always reads 0.3 k ohms, will this make the car think its always warm? or does it use the voltage more than resistance?

cheers,

Warren

Edited by WazR32GTSt
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WazR32GTSt Grand Master

WazR32GTSt

Posted
  • Author
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yeah but the engine will warm up with cold start maps or normal maps

what does the cold start do that the normal map doesn't? richer?

so in actual fact it makes the car warm up even slower?

what else does it to?

just saying "don't do it because it has to be there for a reason" is not good enough for me

emmission control is there for a reason, but it is usually removed on cars when modified

the stock ecu is always tuned for emmisson control remember

RBFIRE Experienced

RBFIRE

Posted
Posted

I think the only down side is you will running rich all the time,

even when you car is warm up!

you will get really bad fuel comsumption!

because it doesnt know what temperature is your car at, and it keep send the same pulse, and that is how much fuel you going to get all the time!!!

nfi Community Regular

nfi

Posted
Posted (edited)

Your car won't start on if you don't give it the cold start "rich" map. When the block is cold the fuel wants to turn to liquid (from a gaseous spray) on the cold metal eg. the bore. Therefore you need much more fuel present to make up for the fuel that is sitting as a liquid on the side of the bore and on the top of the pistons.

Also when the engine is cold you will notice the engine idles higher, this is to help get the oil circulating as quickly as possible and to help heat everything up.

A rich mixture does not stop the engine heating up as much as you would think. Remember the engine is only near on idling.

So basically forget about it. The car won't start easily at all and the engine once it does start will want to stall as well as it not being looked after while it is cold which is when you do most of the damage.

If you have a rough idle when its cold I would be looking at other things. I have seen r32's idle nicely cold so I would be looking at leads, spark plugs and coilpacks.

Hope that helps.

Edited by nfi
WazR32GTSt Grand Master

WazR32GTSt

Posted
  • Author
Posted
Your car won't start on if you don't give it the cold start "rich" map. When the block is cold the fuel wants to turn to liquid (from a gaseous spray) on the cold metal eg. the bore. Therefore you need much more fuel present to make up for the fuel that is sitting as a liquid on the side of the bore and on the top of the pistons.

Also when the engine is cold you will notice the engine idles higher, this is to help get the oil circulating as quickly as possible and to help heat everything up.

A rich mixture does not stop the engine heating up as much as you would think. Remember the engine is only near on idling.

So basically forget about it. The car won't start easily at all and the engine once it does start will want to stall as well as it not being looked after while it is cold which is when you do most of the damage.

If you have a rough idle when its cold I would be looking at other things. I have seen r32's idle nicely cold so I would be looking at leads, spark plugs and coilpacks.

Hope that helps.

i have tried changing many things from coils to plugs to filters etc

also... R32's dont have leads

benl1981 Grand Master

benl1981

Posted
Posted
I think the fuel maps are controlled by water temperature, not ambient air temperature...

I had a very rough idle after a PFC tune that leaned eveything out. By increasing the correction (adding more fuel) at low coolant temps I have smoothed the idle out.

Be careful - you may already be too lean at cold start. Could be fuel pump, clogged injectors etc.

If you get a PFC you can fiddle with things to see what works..but the standard maps should be fine - you either have a sensor or part that isn't doing its job..

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