I have a 1988 RX-7 SE, 112k miles. I was experiencing severe hesitation around 3,000RPM and at high load for several days. Example: starting out for work, would experience problem, would pull over and rev car in neutral for awhile. Would then be able to get onto the highway and drive 15 miles at 65 mph with no problem; then drive home with no problem. On about the 4th day, got onto the highway but then could not go over about 40mph. Got the car to a Mazda dealer. They say that the secondary injectors will not open and that the cause has been traced to a malfunction in the ECU (what they call the PCM). They say that using a engine signal monitor hooked up to the ECU, there is 12 volts at the secondary injector pins but that the ECU will not 'cycle' to open the injectors (they are opening the throttle to simulate high rpm/load ?)

The dealer wants $1,100 to put in a new ECU. They said they do not advise using a rebuilt or used ECU.

I really do not want to put this kind of money into the car. Does anyone have any advice?

Brooks Davis

 

i think they are just telling you to put in a new ECU to take your money, I would just get a used ECU. Just go to the For Sale section and maybe you can find a local guy selling his.

 

A clogged fuel filter can cause the same symptoms.

some other things to check:
Tranny neutral switch.
Boost sensor.

 

You can also read out the boost/ pressure sensor from the ECU while car is running, I think (along with a tach signal) that's what "tells" the ECU to turn the secondaries on (it connects via vac hose to intake manifold). Also check to see if the vac hose restrictor is clogged, it's kind of a plug with a small orifice shoved into the vac line near the boost/ pressure sensor, aft of the air filter box. If this is clogged, the sensor won't be receiving a vac signal. Good luck...

 

make sure your secondaries are plugged in correctly/all the way.