1990 S5 RX7 NON TURBO


i have just adjusted my tps using both the lamp method and the multimeter method. The TPS is set correctly


Problem is im still idling at 1400 or so.


I found out that if im at a stop, the car will idle at 1400. In first gear, as i release the clutch and load is turned over to the engine causing it to dip under 1000 RMP

THE IDLE FIXES ITSELF! i stay at a steady 800 RPM but once i blip the throttle, the rpm climes back up until i put load on the engine.


I found this thread pretaining to my problem, post 6

https://www.rx7club.com/2nd-generati...-1-0-a-896116/



Im guessing my BAC valve is dirty and needs to be cleaned? Can i just temporarily unplug the connector and would this be a temporary fix?

 

My old Mx6 did the same when I converted it to manual trans (still using auto ecu btw).

Within a couple of months it sorted itself out. I would do the same when pulling up at lights etc, just release the clutch enough to drop the idle down and then it would stay there no problem.

Wondering if the AFM might be jamming....

Has it just been put back on the road?

 

AFM is something ive thought about too

Yes i drive the car every other day to school and work. Drives perfectly fine aside from the idle

 

if its idling @1400, first thing to check is the thermowax, most of the time the hoses clog, although it can be out of adjustment, or bad. next step is to adjust the idle speed, there is a screw in the top of the intake on the top for this.

if the thermowax is bad then you will need to readjust the tps once its fixed

 

ok sounds easy enough, im trying to find a picture to where the S5 thermowax is. Or at least find an S5 tutorial on how to adjust it

 

Foxed.ca - Mazda RX-7 Manuals

 

I would say you have a vacuum leak and to check for those. You can use carb cleaner and spray over area. I personally like to hook up a smoke machine and get smoke through the system to see where the leaks are.

 

Ok quick update.

I found that under the thermo wax, theee are two small hoses that go into it. According to the manual that was kindly linked they are hose A and B.

Hose B was disconnected.

Now the car doesn't idle high anymore. Now I have a pulsing idle between 1000-1300 rpm.

So I decided to take on the tps again. Car fully warmed up using the light method. I believe there's something wrong with my throttle cable/tps

Every time I get one lamp to stay on, any minor nudge by my screwdriver or if I slam the hoof shut will trigger both lamps to shut off. Bottom line is that my tps is super sensitive

 

and is likely bad

 

dang, was hoping it wasnt bad. Those tps go for a pretty penny

 

new they do, but you can pick up a used one on here for a decent price, usually under $80

 

ok this is a 3 week bump.

Finally got my hands on a TPS. Holds 1k ohms and my TPS tester now reads correctly!

I STILL GET THROBBING IDLE but its less than before, only bobs 1k-1300 RPM. If i release the clutch in 1st gear and let the engine almost stall (but not let it stall) the idle fixes itself!


now im thinking theres a vacuum leak somewhere. Any common places i should check first?

 

the S5 has a target idle speed, with a small range of correction. if it is outside of its adjustment range, it tends to have an idle surge, for whatever reason.

target idle speed is 750rpm +/- 50, so 1300 is WAY out

 

Why dont you disconnect the BAC to see if that's the problem?

 

Yeah I'll do that for sure but here's something really interesting that I haven't noticed.

Downshifting to first gear in my gated community where I live. The car DID NOT STALL. It actually kept pushing itself in first gear. Never got hesitation to stall. I think this is why my tps isn't working right.

 

Disconnect the BAC valve once it is fully warmed up. If that drops the idle, there is your problem. You can run without the BAC valve completely but your cold idle will suffer pretty badly.

My car had the BAC valve deleted by the previous owner and it still idled fine minus the previously mentioned issue.

Also, check for VACUUM LEAKS.