My brother has pink secondary injectors and we have an s4 ecu. Is this right? The car seems to go lean cruising at 3200-3400 regardless of boost or throttle positions. once past 4000rpm it seems to be fine.

Any ideas?

Ian

 

What year ECU? Also did you test the resistance of the injectors?

 

1988 turbo ecu.
I did not check the resistance. Maybe I should

 

ECU has nothing to do with the fuel injector impedence.
It has to do with the harness.


-Ted

 

You seem to be having a problem when the secondary injectors come online at 3500rpm. When that happens the primary injectors duty cycle drops down from what it was as the secondary injectors now start injecting. That happens at 3500 rpm IF the ECU senses a Load thru the boost/pressure sensor.

If you can drive the car thru that rpm range you mention at a gentle acceleration vs hard throttle, and the problem does not now exist, then I'd say it definetly is a transition problem as the secondary injectors come online.

During gentle throttle application the secondarys don't come online as you pass thru the 3500rpm range and they won't come online until waaaay up the rpm range when a load is put on the engine.

 

the car will show signs of a little bit of lag and the a/f/m shows lean spot on slow throttle when the secondary injectors kick in, on hard throttle i don't see any lag or leanness this all happens between 3500-4000rpm at low to med throttle

 

Secondary injectors don't come when your driving in an easy going mode. They only come on when the engine is under heavy load and at 3500 rpm. The load is determined by the boost/pressure sensor.

IF the vacuum hose is disconnected from the pressure/boost sensor, then the secondarys will come on each and every time you reach thirty five hundered rpm whether your romping on the throttle or ***** footing it past 3500rpm.

The sensation b/t the 3500 and 4000 rpm you describe is probably the secondarys coming online.

Your problem seems assbackwards of the usual problem. Usually they complain of no problem at low or slow throttle transitions past the 3500-4000 rpm but do have a problem when romping on the throttle.

I fixed my early 87 problem by splicing in additional ground wires to my ECU grounds. Others can't fix theirs by doing this. But on mine, if I remove the additional ECU grounds, I'll have the hesistation at 3500 under hard throttle. IN other words I can make the hesitation come and go at will.

Maybe someone else will pipe in with a fix for you since your problem seems opposite mine.

 

If its 86-87, the resistance is lower than some 88, and all s5 and up.