Hole in intake right in front of the butterfiles bottom left. picture.
 

What is this for? My idle is high but if i block this off with my finger it drops to the right idle RPM. It sits about 1500 RPM otherwise. It then will start jumping about as if it's hunting idle. Switching between holding 1500 and bouncing between 720 and 1500. Car is on Apexi PFC base map. https://cimg7.ibsrv.net/gimg/www.rx7...ed9622f8f3.jpg

That hole feeds air to the ISC. The ISC is probably stuck, remove it from the car and clean it with carb cleaner.

Also good to hook 2 jumper wires to it and pulse it open and closed with 12v to work the solenoid back and forth.

Dale

Many thanks mate will give that a try.

https://cimg2.ibsrv.net/gimg/www.rx7...e5f0d99bf.jpeg
If you remove that idle screw completely for cleanings and then you screw it back and seat it completely, if that doesn’t lower your rpm don’t forget you have two other idle adjustment screws on the side of the throttle body. If none of those lower that rpm or take care of the idle hunt you might want to start looking for a vacuum leak as well as checking and adjusting your tps within spec.

Ideal will give that a try. The TPS was way off but I've noved that to within range it did help but still not quite right. Will give these other screws a try. Cheers mate.

Man, maybe I've just had bad luck... but any time there's been an idle problem on my FC or FD and I messed with the throttle body screws it just made matters worse. To top it off the idle screws have never actually solved a problem and once i fixed the actual problem they were a royal PITA to get set right again.

My suggestion is to do the ISC valve as Dale suggests and mess with the TB screws as a last resort.

^Yep. Dead on there.

Dale

IIRC, the RH circled horizontal adjuster screw is used to set the secondary throttle plates to close as far as possible w/o binding. So it's not really an idle speed adjuster.

Link to related thread: https://www.rx7club.com/3rd-generati...ght=hesitation

The only TB adjustment you should fiddle with is the idle bleed screw

https://www.rx7club.com/power-fc-for...le-pfc-176089/

You may also have a vacuum leak

It doesn't help that the PFC idle control is less than desirable

Cheers lads will give the ISC a blast when I get time to pull it off.

Ok so the thermal wax comes out as it heats up. The ICV I've cleaned. the issue isn't as bad but still exists.

As the car warms up the revs climb, the revs bouncing i can stop by adjusting the idle screw on the top left the holds the butterflies open but I can't get it below 2000 rpm without it starting to bounce again. On the commander when it starts bouncing it shows injector duty going 7% 0% 7% 0%.

I can lower the revs with the butterfly adjuster down to 800rpm but, when restarting it it idles at 400rpm and struggles to get going.

I'm starting to think the only way to solve this is have it mapped. I've sprayed as many of the vacuum lines as I can see so other than having it pressure checked and smoke tested.

Does the ISC have the metal gasket between it and the intake manifold? If its' the old paper gasket you could have a vacuum leak there.

Does the idle still come down/settle out when you cover that hole in the throttle body?

Dale

Bouncing RPM is often a sign of being far too lean. If you have a vacuum leak, decreasing the idle RPM makes the lean condition worse because now a greater % of the air going into the engine does not create vacuum at the throttle plates, so not enough fuel is injected. This fits your scenario. So I'd suspect a vacuum leak.

Spray some carb cleaer around the engine bay while the car is idling. If the idle changes, you know you have a vacuum leak.

Be careful with that - most carb cleaners are flammable. Flammable is what you need to detect a vacuum leak, but don't get it on a hot exhaust manifold or turbo.

Seems like some kind of plastic to me. It's red in colour.

Yeah it does still settle down. I did try to move a vac hose out the way to get to a bolt i dropped in the rats nest and it totally snapped off. It was rigid, need a new solenoid now too cause it snapped off the barb part of that too. Hardly touched it!

Think you're right after the snapping hose incident earlier. Im on the PFC base map.

Sounds like a paper or homemade gasket. That could be a lot of your problem.

The FD originally had a paper gasket that was crap. Mazda updated it to a metal gasket. No RTV or anything needed on it, just make sure both surfaces are clean with no gasket crud left on them and install.

This is the metal gasket -

https://www.atkinsrotary.com/store/9...A1-20-661.html

May be able to find it closer to home. That has the correct part number.

Dale

Ideal cheers mate will get one ordered now.

So smoke test proved 3 vac hoses perished and one faulty one way valve. Replaced all these, Apexi relearn idle and now it's idling perfectly. Sits around 720 spot on. Cheers for all the help lads.

Thanks for following up.