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Hello all. While this is my first post, I have been checking in on you guys for years to get information I need at times. This is one of those times. My 84 Corvette that I bought brand new has a rough running condition. While it only has 7000 miles on the odometer, that mostly occurred during the first two years of my ownership, I do get it out and exercise it on nice days. It starts right up but loads up immediately and dies. It’ll start up again after cranking for a while and with a heavy foot on the throttle, it’ll clear out and idle. The only code it will display is 12 which it is supposed to. Can anybody advise me as to where I should start looking?
The 84s had an early type of coolant temp sensor, they were known to be troublesome. Try wiggling it while its running, see if it affects the idle. It's at the front of the intake above the water pump. If you do replace it, use a newer style sensor and connector.
Sounds like a fuel problem. Lucky you that it is a Cross-Fire where you can remove the air cleaner lid and look at the injectors spraying.
Have someone start the engine while observing the injectors. My guess is that it is dumping way too much fuel in there.
By keeping the throttle floored you enter a "clear flood" mode where injectors stop spraying fuel, or spray way less. You can verify that too.
And when the excess fuel is gone it starts again.
A broken, open circuit, coolant temp sensor will fool the ECU that it is -40 F ( also -40 C ) and run very rich.
You can measure the sensor with an ohm meter to ground.
No it doesn't work that way, the ecm sends 5v to the sensor and reads what comes back. It can't do that with a one wire sensor. Here's a picture of an 82, same as my early 84.
Thanks guys, this is helping me a lot. I located the temperature sensor which has a white plastic retainer of some sort and two wires, one black and one yellow. Looks like a bear to get to. How much fluid am I going to lose when I remove it? Also, what sensor should I replace it with? You mentioned replacing it with the upgraded sensor and connector. Do you have a brand for me?
The 84s had an early type of coolant temp sensor, they were known to be troublesome. Try wiggling it while its running, see if it affects the idle. It's at the front of the intake above the water pump. If you do replace it, use a newer style sensor and connector.
my sensor was corroded, cleaned up was all it needed on mine
Will I lose a lot of fluid when I change the sensor?
The sensor is quite high, but you will drain what is in intake and thermostat housing. You could open radiator cap and drain the radiator tank using the drain plug in the lower right corner of the radiator. This will minimize coolant at the sensor.
Thank you. I ordered one from rock auto. Hope this solves my rich running condition. Will I lose a lot of fluid when I change the sensor?
Have the new sensor ready. Get the old one loose, spin it out w/your fingers, when you can feel it's fully un-threaded (you're holding it in w/your fingers and thus, plugging the hole)...hurry/quick, pull it out and stick the new one in the hole, then start threading that one in. You can do it w/o losing more than about a 1/2 cup of coolant.
Crossfire issues
