1993 rx7fd base
Hi, I have a high idle problem where it just come out of no where. A month ago I was pulling back into my drive way and the idle slowly climbs up to 2500 and would not go back. I did followed the thread on (DaleClark's guide to idle troubleshooting (high, low, bouncing) - RX7Club.com - Mazda RX7 Forum) but still could not figure out where could the leak or issue is at.
Before the idle problem I did have a leaking cat convertor and I replaced it with a racing beat race pipe(hoping it may resolve the idle problem but it did not) so the air pump is not engaged with anything. The pump is still on there currently I use it as a tensioner for the belt.
I replace the gasket and cleaned the IAC but did not help, but if I disconnect the IAC plug the idle would drop to 2000.
Thermowax valve is the next thing I checked, I tested it with hot water and it expands and retract as it should, I also manually push down the stop screw for the thermowax valve when the car is running but it didn't help with the idle. I did twist the stop screw tighten than before and it drops to around 2300 rpm.
Lastly I sprayed starting fluid on the throttle body, UIM, vaccum hoses and lower intake area try to figure out a possible vaccum leak from hoses or gaskets but it seems like there are no leaks as the idle didn't drop or increase while spraying around.
Please help with this issue, I have been trying to fix it in the past months and still cannot find any possible solutions.
Thankyou for your time helping me out.

 

check your throttle cables to see if it or the cruise control ones are tight, indicating a jammed cable holding the throttle open.

there should be a little bit of slack in both of them.

 

Also, take your intake elbow off and spray some starting fluid at the closed butterflies, or alternatively, take the TB off and shine a light from the back side of the TB and see if there is light coming around the butterflies.

If someone had, in the past removed and cleaned the factory coating from around the butterflies, that could be your vacuum leak.

 

Got it thankyou people, I will do that as soon as tomorrow

 

Just got back to the car and find out that there isn’t a cruise control cable and the throttle control cable has some slack

 

 

before I took the tb off, I did a smoke test and found out there is a leak below my airpump area, never thought there would be vacuum lines down there thought they are only around the UIM

 

Problem solved( kinda), it's the lower intake manifold gasket that's causing a vaccum leak.