Crank no start

[KyFried]

1999 mazda b4000 4x4, extended cab I have been fighting this for a while now, I replace the idle air sensor and it starts but when it gets cold it won't start, now what I mean by cold is only 48 degrees, It started last night temp was in the 60s, this morning it won't start is there some sensor that deals with temperature?

I can hear the fuel pump activate when I turn the key on, check engine light is not on. Any help or suggestions will be most appreciated.

 

[RonD]

ECT(engine coolant temp) sensor tells the computer how much "choke" to use on a cold engine.
1999 4.0l will have 2 temp sensing devices on lower intake just above thermostat housing.
1. ECT sensor, it has a 2 wire connector, only used by computer
2. ECT SENDER, it has a 1 wire connector, only used for dash board temp gauge.

They look similar, difference is 1 wire or 2 wire

You can test them with volt/ohm meter, but ECT sensor should only cost $5-$8

Common symptom for incorrect ECT sensor temp is hard cold start, usually not no start, and low idle, and then poor running until engine warms up a bit, this is because ECT sensor is telling computer engine is warm, so computer never increases idle(opens IAC Valve farther) and doesn't add the extra fuel a cold engine needs to stay running(the Choke part)

Not sure what the "idle air sensor" is, the IAC(idle air control) Valve could be what you mean.
IAC Valve is a control not a sensor, just FYI.
There is an IAT sensor, (intake air temp) sensor, it is part of the MAF sensor, but it couldn't cause rough running or a no start

 

[monstermazda]

Could be the MAF or air temperature senor as well.
If it can't rear air density and temperature it could cause it to

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