hey guys!

So, my engine swapt (1987 Turbo with a "new" used 1987 TurboII engine) is finally finished

the engine runs soooooooooooo sweet smooth at IDLE, everythin works...
the car pulls fine in the low RPM's, the turbo is spooling up like on LSD or XTC...

the complete engine harness had been rebuilded, every cable is in perfect condition...

but we have a problem... the engine is fine up to 3,8k rpm, then it feels like i hit a wall and i have a little backfire... so my secondarys are'nt fireing right!?

so, what could cause this?
tommorow i will swap my "old" secondarys from the old engine into the new...

what are the reasons for not firing the secondarys?

bad injectors
bad harness (impossible)
bad ECU (it's the same ecu like it was before... should be fine)
...
???

pls help me out... the car must run tommorow

 

grounds

 

which grounds exactly?

i've redone ALL grounds in the engine bay...

 

by the way, we have tested the car with an original Mazda tester... no errors

 

the ground that goes to the rear iron, should have two wires going into that ground also the one at the firewall.

 

You could get a meter and back probe one of the Secondary injector wires at the ECU. Below 3500rpm the reading will be whatever the voltage the alternator is putting out. Once you cross 3500rpm AND have your foot in it, the voltage should drop dramatically. Say from 12vdc down to 7vdc or even as low as five.

If the voltage does as above, the injectors are firing. If it remains the same, the ECU isn't pulsating a ground to the injector.

You can do the same in your dirveway if you want. BUT you have to pull the vacuum line off the boost sensor and plug the line. Now everytime you reach 3500rpm the voltage will drop on the secondary injectors WHETHER OR NOT you have your foot in it. Even gentley acceleration above 3500rpm will trigger the secondary's to come online. BUT the voltage drop will NOT be as dramatic as describe above with everything connected i.e. vacuum hose to boost sensor.

 

engine runs fine now...

one secondary injector was fucked up :/

 

People need to stop posting "grounds" for every damn problem that comes up. If he really had a probelm with the grounds that stopped the secondaries from firing, then the whole engine would be completely dead. Just saying "grounds" shows you don't really understand how electrical systems work.

A problem like this usually means a secondary injector plug has been left loose or fallen off or a secondary injector is dead, which proved to be the case.