I've been reading these forums for a while but this is my first post. So how is everybody doing?

Anyway, it's a 91 NA rx7 with 115k miles, only mods are an exhaust and a messed up shifter (still works tho). The idle bounces between 1000 and about 200 rpm. If the AC is on, the motor will sometimes stall out when out of gear and idling.

This is the strange part- It does not always have this bouncing problem. It only does it about 60% of the time. It does not seem to be linked to motor temp, as in it will sometimes do when the motor cold or when it's been on for an hour. Sometimes its fine for half a trip then starts to bounce. When actually moving with my foot on the gas it's fine.

I've tried spraying throttle body cleaner to check for vacuum leaks but I did not find anything. I adjusted the idle skrew and that didnt seem to have an effect. I changed the air filter and again no effect.

I don't think it is the TPS because the car is fine while moving. I think it might be the butterflys inside the throttle body but I have not gotten a chance to check them yet. Could it be a seal? fuel injection problem? vacuum leak?

I'm running out of ideas... any help would be great.

 

my 90 GTU does the same thing. I wouldn't worry about it much. Does yours run super rich? If so, that's why I think. That and do you have your Air Pump running? As you should know, on the s5, the air pump closes the exhaust ports. It's a must on 89 to 92 unless you replace it with electronically controlled ports. Make sure the pump is operating fine. If it is, then, I don't know. I just need to increase my idle a little bit. I idle low until it warms up.

 

I haven't checked the air pump. I'll do that.

The car smells like its running really rich and it uses a lot of gas. Can I change that myself or do i have to plug the car into a computer?

 

Hope this helps, furry boy

http://rx7.subbuteoclub.com/idlecontrol.shtml

 

Very nice. So next noob question: do I simply replace the BAC or CAS? It sounds like it would be the CAS because the motor actually dies when the AC is on and the car is in idle.

 

wow, don't do anything from that. It's for an s4 you have an s5. The elec system is different and the exhaust ports are controlled differently

 

okay, the BAC and CAS is okay. Don't mess with the electrical stuff. Forgive me, I didn't read anything but 86-88 before I replied

 

so does anyone know what you're supposed to do if it is the BAC and CAS?

 

Uhhhhhh.... the ACV has nothing to do with the exhaust ports. Neither does the air pump.

It does sound like its the TPS, if its on the boundary of the ECU seeing on throttle or off it will idle incorrectly.

https://www.rx7club.com/2nd-gen-archive-72/faq-idle-problems-334730/

check through all of that. Read the archive and faq plz, thx.

 

k- reading it now, ty

 

Looks like I got some work ahead of me. I can't do anything on campus so I'll start next weekend.