Adam

88 Gxl rx7
OK SO.. i work on my rx7 all the time.. thought i knew almost everything about it... However i have cold start problems now and i cant find the reason for it... Car Wont run Below 2k when cold. When ingauge the Clutch the car dies when the RPM falls..

Now this last for a short time till car is warm.. When warm restarts Fine...

When car is Cold and i am on a flat surface and i am forced to use the starter Back fires and takes a long time to get going..

When Compression starting when cold takes a few seconds but starts right up when rolling the engine above 1k to start

When it does start wont run below 2k rpm... Spark is fine. New spark plugs. Fuel pressure is good..

Seems that some sensor is making the car run to rich maybe.. Whats wierd is it used to SKip the cold start up prosses and Start like it was warm all the time. Never did the 3k cold startup till last few weeks...

How can i start my car and have it think the engine is already warm.. Im really lost right now... Thanks

RotaryRocket88

iTrader: (7)

Two things come to mind. The temperature switch on the bottom of the radiator, which has a role in the cold start assist system (3k RPM start), and the water temp. sender on the back of the water pump housing. If the coolant is cold enough, the temp. switch allows the 3K RPM startup. And while below operating temp. (180F), the ECU enriches the mixture thanks to the temperature sender's resistance value. As the engine warms, the resistance changes and the ECU slowly leans the mixture back out. I'd start by checking out both the switch and sender. Higher RPM and a richer mixture (to a point) will help cold idle, so what you're experiencing is more likely a mixture that is too lean. If the temperature sender is at fault, a "warm" signal would lean out the mixture too soon after startup.

Adam

The only wire that go's to my radiator is at the top for the Coolent level sender... Thats it.. However,I will check that green plug agian on the back side of the thermostat, And a few other things..

Is there anything on the UIM that i should check that has to do with cold startup?

Thanks for the reply. i will check those..

If i can find the Correct sensor that is doing this. I hope to find a warm value maybe get some kind of resistor? If anyone has done this please let me know... thaks agian

RotaryRocket88

iTrader: (7)

The temperature switch I mentioned has 2 wires, and is located on the bottom of the driver-side of the radiator. But the temperature sender would be the more important of the two, since it affects mixture. Other than that, the air intake temperature sensor on the UIM has a small role in mixture calculations, but I wouldn't suspect it as much. Water temp plays a bigger role. And as far as adding some resistor in to try to get the "warm setting," you don't want to do that. That would be making your current problem worse by leaning out the mixture further. Engines simply run better once they reach full operating temp, which isn't something you can fool the ECU into doing while cold.