wiring diags extracted from FAQ section:

http://www.scuderiaciriani.com/rx7/fan_circuit.html

"This was my case. It made the "quick fan mod" useless for me"

If you grounded the test wire, engine cold, would the fans come on in 2, 4, or x minutes? If so, per circuit diag, the 226F thermoswitch (miata 207F) would work the same way. If just 2 minute delay, thats the lag after miata switch trips, and when the fan module supplies voltage to the motor slow/med circuits.

If ground wire does not kick fans on cold after x minutes, then miata switch would just give you med speed at 221F, instead of slow (ac off).

 

well i get (relatively) regluar fan operation... except they seem to come on late, and if i then slow down into traffic the car cant deal with the extra heat buildup, and it overheats. so im debating replacing the thermosensor (for the 190F one) as well as replacing the regular temp sensor (which if its teh same sensor that the stock POS temp gauge uses... it does some weird things). ive changed the thermostat, installed a koyo, and bought some 1.3 bar caps (which i havent installed yet). i may also have a leak somewhere in the system... i have to pressure test it.

the other thing that i was contemplating doing was bridging relay #3 -> #1. this seems like it should activate both left and right fans on MED when the 190F thermosensor is tripped. therefore, in traffic i would get 2 fans running instead of one, the AC switch should continue to function as it always did, and i would get full high (4 relays running) to bring the temp down quicker when the ECU activates #2 and #4. otherwise the current setup dictates that relay #1 will NEVER be activated unless when the AC switch is engaged... preventing the fans being on full high from happening under normal circumstances. can anyone think of a reason NOT to bridge #3 -> #1?? id like ot get a discussion going on this possible mod as (to me it seems promising).

just to clarify.... 1) is the sensor that the stock ecu reads for temp. readings the SAME one that my stock temp gauge bases its movement on?
2) will the 190F miata thermosensor ACTUALLY turn on relay #3 @ 190F???

-heath

 

Nope, the fans come on around 207F (on my car that is).

 

What temps are you seeing?

 

If it overheats just idling in traffic, then you have some cooling issues to deal with other than just getting the fans to run earlier...
Once again, the fan motors are wired in parallel. They cannot work singularly.
Yes. The activation of relay 1 is controlled by the ECU, which automatically raises the idle rpm to compensate for the additional drag created by the A/C compressor and the added current draw on the alternator from the fans.

 

Or if you knew a friend of a friend whose first cousin's uncle's wife's step-son from her fourth marriage knew someone who is friends with his next door neighbor's oldest son that owned an RX7 before selling it to someone who previously owned an RX7 before wrecking it who had already purchased a PFC along with a Datalogic... then you wouldn't have to worry about buying one

 

Well, I wouldn't call that a wiring update... that would indicate rewiring or removing a wiring harness and replacing it with an updated one

 

No. The stock ECU reads off the thermosensor on the water pump housing. The stock temp gauge reads off of a thermosensor unit on the rear engine housing.

 

They do remove part of the wiring harness, and replace it with an updated one. The wire routing to the relays and ECU is different. That is why the voodoobox fan mod won't work on med/high fan speed with the fan wiring update installed.

 

Well **** the bed, I learn something new everyday.

 

Strange, assuming you had a good test ground, the mod switch should have given instant on fans, if miata switch does it. This is based on modified wiring diagram link I provided before. Per my notes, part of the recall work final testing for the mechanics states that with test wire grounded:

pre apr 1 93 --- p0210660 --- fan operates with ign on.

aft apr 1 93 --- p0210661 --- fan operates 100-150 secs aft ign on.


Bad ground path for the test wire?

 

Nope, the ground is good (the switch is a lighted one so it wouldn't light up if it didn't get grounded). Probably just Mazda messing up something when the recall was done.

However, it doesn't matter. IMO, the Miata Thermoswitch is a better cooling modification if the person doesn't have a programmable ECU to change the temperature the fans come on.