Idle Hunting & High Idle
 

1987 T2 with under 50K miles.

Idling around 1200RPM and bouncing. Turning on AC stops bouncing but high idle remains. Unplugging TPS stops bouncing but high idle remains. Did vacuum leak check and plugged a few leaks with no impact. Tested TPS and it seemed ok.

Any other ideas?

When adjusting the TPS and idle are you jumoering the test connector?

Vacuum leaks cause higher idle conditions. Especially if you cannot lower the idle manually. As far as the bouncing idle. I see this coming from a rich to lean condition. Not sure how to fix with stock car. Cloker probably has some good information for ya. Have you changed fuel pump?

I believe I did, but will do it again warm up > shut off > jumper test connection > remove intercooler > use Ohm meter on TPS. 1K on top/lower right pin and 5K +/- 1K on top/lower left pin.

Hunted down some vacuum leaks. Still a small one coming from under the throttle body.

What is best method to manually adjust idle? BAC valve screw? Mine came to me almost completely turned to closed.

Well you can turn the throttle screw clockwise and down to lower throttle. It is on the very top middle back by the firewall it is behind the tps. Closed BAC would mean that its not much you can change there. That is used for A/C and fine tuning when extra load comes on. I usually blow smoke through the system to find vacuum leaks. There are lots of vacuums on this car. Quite a few underneath the throttlebody and on the front and back side as well.
There is an initial set coupler on the driver fender between the engine fuses and headlight that needs to be jumpered before setting the idle. I never ever jumpered this before I adjusted idle though.

Is it doing this? *Warning, language*

This guy found the problem to be "A SOLENOID WAS STUCK OPEN "

H
 

Yes, very similar

I don't think that the idle screw was making contact at all when idling but the car may have been cold

I don't think that the idle screw was making contact at all when idling but the car may have been cold

TPS TESTING QUESTION

I followed this procedure:

RX-7 Throttle Position Sensor (TPS) Testing / Adjustment : 13B Etc - Mazda RX-7 Parts And More

I was able to get correct readings between terminals A&B for both open throttle and idle. However, the reading between terminals A&C are reading 2.2 open throttle and 6.8 idle. I cross checked against the service manual (4B-49) and there is no mention of testing terminals A&C. The above link said it should read 5 +/- 1 in both idle and open throttle.

Any thoughts on the test between A&C?

SMOKE TESTING FOR VACUUM LEAKS

Pressurized with smoke earlier and fixed a few vacuum leaks. Only two remaining are coming from the front and under the throttle body. I can see vacuum hoses running under the throttle body but the smoke from the front looks like its coming from the throttle body itself. Thoughts?

https://cimg5.ibsrv.net/gimg/www.rx7...1da19f910d.jpgSmoke coming from under intercooler airpipe
https://cimg6.ibsrv.net/gimg/www.rx7...583ffb5b41.jpgSmoke from front of throttle body

The screw isn't even touching the cam. I actuated the dashpot and slacked the accelerator and cruise control cables but the gap in the picture stayed the same
https://cimg8.ibsrv.net/gimg/www.rx7...e63123d9e.jpeg

THERMOWAX UNIT ADJUSTMENT SCREW & THROTTLE SCREW

So I did some anatomy homework on my throttle body by looking at someone's detailed ebay pictures from a removed part (thanks crpartsplus). I went to go look at my thermowax unit and see an adjustment screw with spring sitting on top of the rod. When I lift the screw and spring and release it does not snap back to the rod. Is this normal operation?

In doing so I did see that the extension of the thermowax rod does bring the cam to that idle screw mentioned earlier and closes the gap.

So I snapped a quick picture.
#1 is the screw you are looking at. To be honest I I have never touched that screw. Mine is in the same position yours is in.
#2 is the idle adjustment screw.


https://cimg8.ibsrv.net/gimg/www.rx7...613e46edd7.jpg

As far as TPS adjustment I like the link below. Also I mainly worried about the 1k adjustment as the idle was usually the mystery I was trying to solve. This is the the S4 Turbo II model. I am not sure if there is a difference right off.
FC3S Pro v2.0:&nbsp TPS adjustment for 1986-1988 RX-7 Turbo II models

DMM measuring approximately 1k-ohm with throttle at rest/closed.

If stock cold start system is still intact, engine must be warmed-up before checking TPS resistance.

Thermowax
 

QUOTE=smikels;12264543]So I snapped a quick picture.
#1 is the screw you are looking at. To be honest I I have never touched that screw. Mine is in the same position yours is in.
#2 is the idle adjustment screw.


So I warmed up the car for about 15 minutes, shut down, quickly removed the intercooler and went to look at the #2 screw (which sits on top of the thermowax rod) and adjust the TPS. I noticed that after 15 minutes of idle, the thermowax rod had not extended and pushed the cam. I have noticed my Rx has been running very cold after I did a coolant flush some time ago. I wonder if the t-stat is stuck open and the thermowax is never getting up to temp in order to set the

The thermowax can be removed with a 17mm wrench. This way you won't have to worry about that throwing the reading off. Also if you lift up on screw #2 you will see the screw # 1 now hits. But this will never be hit really from what I can tell. Of course those couple leaks will make the car's idle run a little higher. But you should be able to warm it up and make adjustments I would think by turning the screw #2 down or clockwise to lower the idle. The car swill still warm up even if the t stat is open it just takes longer since it is flowing coolant already. Also the weather is still cooler and it takes longer for the car to warm up. Maybe take it for a short drive and back.

So I changed the thermostat and thermosensor and its still running cold. The idle is getting weirder. Now its hard to start but will start and start idle hunting right away. Turning on the AC makes it better. Oddly enough it will idle rough and then smooth out when the electric fan kicks on and then back to hunting when the electric fan kicks off.

Still noticed the thermowax is not extending and moving the idle cam.

Here are two videos, engine bay and interior:

Here is a big thread on lots of people having this issue. Seems it can be many different things. Take a look and hopefully you can check out the things they are suggesting if you haven't already. Their are lots of things that can cause this condition according to this post. Most seem easy enough to see if that is the issue just by making an adjustment and seeing if it changes your condition. If it doesn't put it back to where you had it though so you do not adjust to many things at once. You also had a vacuum leak as well did that get fixed? It is the car fighting to correct idle between a lean and rich condition.

https://www.rx7club.com/2nd-generati...00-rpm-162598/