Zipdrive 20

Earlier questions were about coil identification and O2 sensor threads. That's done and there were problems. So far:
1) Replaced very old O2 sensor.
2) Corrected coil wiring, leading and trailing were reversed.
3) Found and replaced bad leading ignitor.
4) Set timing correctly, was off.
5) Found broken wire on Ambient Temp sensor (Under BAC). I soldered this and checked with a meter and it does change with hand warmup.

Engine is coming around, has much better power now. Gas mileage is still 15.5 best but that's not babying and not redlining every shift either. I need to try a baby tank, I understand 17 in town is about what I can expect.

Still there is a rough idle. Not as bad as before. Here are the symptoms.

Starts well cold or hot. Cold goes up to between 1.5 and 2K which I believe is normal. Drive off gently and when up to temp idle comes down to around 900. Shut the engine off, start 30 minutes later and the idle is rough and down to 650 and struggling. Doesn't shut off just low and rough. Drive through the gears a couple of times (simply revng up doesn't change rough idle much) and it's back to 900 and relatively smooth. Not silk smooth like I know it can be with a rotary, but nice.

There are three adjustments that I would like to check. The first I did find in the books and on this site, just want to confirm I set correctly. Found the throttle stop lock nut loose! Started up the engine and set this so I had some range in the screw setting right on top of the dynamic chamber, both screws circled in photo. Haven't driven since setting this but idle is good at 900 after a warmup drive. Did I set this correctly?

The other two screws I cannot clearly identify in the books. They may be set correctly but I want to at the very least know their function and confirm they are set correctly.

Thanks for any help.

Aaron Cake

iTrader: (1)

Been a while for me on a stock GSL-SE, but I believe the first picture is the idle speed air bypass adjust screw. It adjusts the base idle speed. The second picture is the cold start cam thermowax adjust screw. It adjusts how far the thermowax opens the throttle.

A few things to check before messing with ANY of the hard adjustments:

1. Vacuum leaks!
2. TPS calibration
3. BAC operation

If you have issues with any of the above, you'll just be chasing adjustments.

The GSL-SE may also require an "initial set" coupler to be jumped in order to make hard idle adjustments. This will set fixed timing and stop the BAC from trying to fight your adjustments. Confirm in the FSM.

Zipdrive 20

Thanks. Yes, I carefully read everything I could find and have checked the TPS, BAC for proper operation and vacuum leaks. I am sure the TPS is set correctly and the BAC works. One possible oddity, when checking the TPS I only read 10.5 VDC, never 12. Is this normal? Nothing is on in the car except the key switch. No fans, no radio, nothing except possibly the dome light.

There is a connector you remove that disables the BAC, maybe this is what you mean. I'll wait for confirmation though before moving further on the hard settings.

Vacuum leaks, well I listened as well as I could and will research the site for better methods.

There are two red circles in the second photo. I assume the lower one is the one you identified as the cold start cam. What is the upper adjustment?

FYI I am not the only owner of this car as you would expect. Just trying to learn and baseline any possible adjustment. Your help is much appreciated!!

Zipdrive 20

Aaron Cake, after looking at the manual again I understand now . Both of these adjustments in photo 2 are adjusted at the same time for fast idle operation. Looks like I need a 77 degree day to check these.

Aaron Cake

iTrader: (1)

Honestly, I don't know what the TPS reference voltage is on the GSL-SE. You'd have to check the service manual. But if it is supposed to be battery voltage and it's significantly lower than that, then yes, I'd say it's an issue. Time to check battery terminals and power to the ECU.

Check the FSM for the proper idle set procedure. If just unplugging the BAC is all it takes, then that's easy.

Zipdrive 20

I have searched and cannot find a coil recommendation thread, probably my search skills in the forum.

Currently the car has MSD Master Blaster 2's. Reading the forum and the MSD site these should not be mounted horizontal, some say they can actually explode.

Of the choices out there, any reccomendations?

Accel
Beck/Arnley
ACDelco
BWD
Jacobs Electronics
OEM Mazda part# N225-18-100
WELLS C843
PerTronix Flame-Thrower II
Mallory Ignition
Summit Racing SUM-G5220 - Street Coils

Any positive or negative comments on these particular or other options much appreciated.

Zipdrive 20

Still waiting for a 77 degree day to check the cold start thermowax. On a 70 degree day it looked way off and I noted the position and adjusted. This did take care of the problem with rough idle after a drive. Starting to act more like a normal RX.

The mileage is now at 17.1 last check, driving enjoyably revving up, not redlining but not babying the drive either.

Thanks all, finally I have all but thermowax correctly set. Idle still stumbles at times, more so on a warmer day. Will continue to read and try to solve. Maybe correctly setting the thermowax on a 77 degree day will take care of this also.