hey guys, ive gotta 87 rx7 turbo 2 with 65k on it,, the car is very mint.. the problem im having is that when i get the car up to 3500 it starts to break up real bad sometimes doesnt wanna go past 4k.. already have checked the air flow meter, boost sensor, set and checked tps, turbo solenoid all checked good.. i blocked vacum to boost sensor and revd past 3500 to hear the secondary injectors click.. nothing, no click,, seems to me that the ecu isnt getting somekinda signal to fire the secondary injectors.. motor was pulled out to replace turbo,, the install looks like it came out right , ,,thank you!

the problem arises from an earthing issue for the ECU , commonly there is a few earths on the engine that may get left off after maint

but more and more commonly its related to the age of the loom and associated overheated /aged joins



what you need to do is find the ECU

then follow the loom a short distance along the 4 earth wires

( black with brown dash ) [ pins 3G, 3A, 2R, and 2C ]

and find the 2 copper crimps where all the other earths and shields bundle together

you add a decent gauge extra earth here to each crimp and resolder the crimps

then bolt the other ends of the 2 new earth wires together on to the ECU case

SO i grounded those wires to ecu and ran an extra to the body for shits.. still wants to break up at 3500, no cat on it either ..running outta ideas, and mazda dont want anything to do with it..any other suggestions? Thanks

next one to check is the two speed relay that drives the fuel pump and the volts at the pump

it may require a bypass so the pump is getting full time 12+ V

( will have no implications on any of the low down running,, just makes the pump life shorter )



its very common for the voltage at the fuel pump to be poor,, usually its this two speed relay ,, or a build up of resistance along the connections

sometimes it is simply best to add a new fused fuel pump relay fed from the battery and use the original fuel pump wiring to swing it

( add relay at the rear under the rear kick panels )



finally is to check that the injectors themselves are receiving full 12+ V

it is common to see it fall down to less than 6V during staging ,, and this usaully indicates issues in the wiring loom or the ECU earths

( as directed in first reply )

PS

change out the EFI filter ( dont laugh --its been the culprit before )

and maybe have the fuel pressure tested

,, you may have to pinch the return hose and see what the output will spike to

as it will be tricky to simulate all the staging parameters while at idle

another trick is to swap the injectors around or pins around at the ECU to check the secondaries actually flow

( they will become the primarys )