https://www.rx7club.com/2nd-generation-specific-1986-1992-17/my-car-possessed-video-848481/
^ previous thread
I cleaned the bac valve and it ran for about a week.
Then i got a new bac valve, and it ran for another week.
Now it is back to running like this. It must have something to do with the weather because it runs perfect in the mornings but once it starts to get hot out, the car doesn't want to idle and when you are driving it in hot weather it hesitates at all rpm ranges. Also when i cleaned the bac valve and changed it, the weather was nice and not hot. So im sure that's the only reason it ran.

im almost 100 percent sure its not the bac valve so is there anything else that can cause this?
thanks


here is the video for those how don't want to look at the other thread

 

TPS?? VAC leaks??

 

no vacuum leaks
and tps is good

 

could be the wax pellet inside the throttle body. If it is not functioning properly it could be holding the throttle out slightly and you are not getting a good tps adjustment. I use to have the same issue where it would surge at idle. I change out intake manifold along with throttle body it solved the issue.

 

^ would the weather effect that though?

 

Have you tried changing out the air solenoid valve? Its the little thing that is on the same side of the intake as the BACV is, though beneath it. I had one go bad on my S4 NA and it caused something quite similar to what you are experiencing.

 

With the engine idling, grab a propane torch and aim it at the air intake. Slowly open the valve to start the propane flowing and pay attention to what the idle does. Does it speed up and smooth out? or does it slow down and get rougher? this will tell us a lot about what needs to be done next. If you don't have a propane torch, I bet a neighbor does.

 

is that to check for vacuum leaks?
i used carb cleaner and didn't find any

 

Yes it is for vacuum leaks or anything that might cause a lean or rich condition. Propane will tell us if it's too rich or too lean. You should never use carb cleaner. Too risky for fire. Several vacuum leaks can occur right above the exhaust manifold. Propane can be aimed at suspect areas to look for change in rpm/ roughness.

 

any other ideas?

 

You say you adjusted the TPS, now did you also adjust the BAC valve and idle set screw? Since you have now changed the throttle position signal to the ECU.
I would set the idle first, then TPS, and finally the BAC valve if needed w/ all accessories on.