I followed the instructions found on the forums to set my TPS on the 90 RX7 NA, and got my car to idle great! The only thing is, when it is warming up it wants to sit there and surge. The idle fluctuates when cold. It seems like a small problem, since everything else works fine.

When I start it, it fires right up and goes to 3k rpm for 17 seconds. Then it fluctuates back and forth between 1-1500k rpm until warm. Once it is warm, it idles right at 800 prefectly. What is causing the fluctuation? Any simple fixes for me? Thanks!

 

Adjust the fast idle cam at the end of the thermowax. I had the same problem

 

Cool, thanks I will go out right now and try that!

 

Surging is cause by one or all of the below 3 things


1.Improper timing
2.Vacuum leak (idle anywhere above 900rpm)
3.TPS not adjusted correctly


Fix all 3 of those things, and you will not have surging.

 

im idling at 1050.... does that mean i have vacuum leak?

 

i've searched to try and find exactly how to set the TPS andone know the link to where i could find this?

 

Don't forget a very bad adjusted mechanical idle that the BAC keeps trying to overcome

 

anyone know the stock adjustment or about where the adjustment screw on top of the throttle body is suppose to be?

 

It's real easy- on a hot engine, jumper the check connector (near the leading coil). That takes the BAC out of the loop, which means only the idle adjust screw and throttle opening is keeping the engine alive...

Turn off all electrical loads not needed to keep her running (if you have an electric fan, turn it off also)...

Now check your idle rpms on the tach. It should be right at 750 rpm, +/- 25 rpm. If high, turn the idle screw clockwise, low, vice-versa...

If the engine dies when the connector is jumpered, turn the idle adjust screw two full turns counter-clockwise, pull the jumper out, and start her up again before reinserting the jumper...

Note that these instructions are for S4 NA's, any other car may be different...