Strange Idle
 

Hi to all.

My project 1990 Rx7 13B has never idled properly.
Today I started the car and miraculously it was idleing perfectly and purring for about 60 seconds and then started the good old roughness.
Didnt run car for 3 weeks. Its been raining alot lately and humid.
the Oxygen Sensor wire is is ripped from the sensor and was never connected..

Why would it idle well for 60 sec for the first time in months. Sensor was never connected yet, as i have to buy new one. Could it be the weather. I have checked for vacuum leaks and all seems well there.

I know that the BAC valve needs replacing or a good cleaning because when I squeeze the air tube there is no change in idle. (I was told it was a good way to check)

Any clues?
Thanks
Nelson

What idle speed was it when smooth? Did it get rough after dropping down as the engine warmed?

95% of idle problems are from vacuum leaks or TPS problems. https://www.rx7club.com/showthread.p...55#post5131155

The 02 sensor is not used at idle; it's only used when cruising at high vacuum/low throttle/low RPM.

It was about 1400rpm, It actually stalled after 1 minute, when I restarted it it was back to the old rough idle. Never got a chance to warm up.