The problem only occurs during hot starting, after it sits awhile it starts up fine.

 

I'm willing to bet your problem is a leaky injector. I had trouble with hotstarts before I had mine serviced.

 

Whatever.

The next time the car won't do a hot start, right away depin wire 3B on the small plug at the ECU. Then start the engine. The engine will start each and every time until the water temp gets under approx 40-50 degrees, then it will be a pain to start but will start.

It all has to do with the graph I posted and the WORDS written under the graph.

To depin a wire all you need is, is a set of jewelers screwdrivers that you can buy at the grocery store for about five bucks.

You pick out the smallest common screwdriver.

Pull the smallest ECU plug.

Look in the mating side of the plug and depress the small plastic tongue that holds the contact on the end of the blue wire with a black stripe.

With the tongue depressed, pull the wire out of the plug.

Reinsert the wire in the plug.

Put a piece of tape on the wires contact. It will have 12vdc on it each time the key is held to the START position.

Go start the engine while it's still hot. It will start. It will start because instead of some outrageous injector pulse width of say 35ms or so, the pulse width will be in the 5-10ms range, letting the engine start and not flood like with the 35ms of duration.

Look at the graph and you'll see what I talk about.

So your 87 has a bit of a *MISS*. With the engine hot, and idling, go to the variable resistor and slowly turn it clockwise and listen to the engine. Did the *miss* go pretty much away? Yes it did. RX like to have a afr of 13 give or take a touch. That's my humble opinion. Plug wires, sparkplugs nor a 200 buck aftermarket ignition system will make that puff, purrrrrrr, puff, purrrrrrrrrrr, puf go away.

Again, pin 3B is a blue wire with a black stripe or L/B in Mazda terms. Bottom row, far right.

 

Hailers,
When playing with the variable resistor does the inital set coupler have to be installed?