1988 S4 NA- Do I have a fuel injector resistor solenoid? I've been trying to locate it under my air box and I couldn't find it? My secondary injectors are not activating and according to our forum a lot of times this is the culprit. Your input is highly appreciated, thanks.

 

No, and why do you feel that the secondary injectors are not working?

 

an S4 NA should not have either the injector resistor OR the fuel pump speed relay

 

My original problem was my auxiliary port wasn't activating.
Things I've done.
1. Pineapple Racing inserts installed.
2. actuators tested, diaphragm ok
3. added T-line running from split air pipe and ACV to introduce more back pressure.
4. Wired open the port, drove and floored the accelerator, car still stumbled.
That's when I came to my conclusion that maybe it's gasoline deprived. Read our forum and a lot of fellow rotarians have the same symptom what I am experiencing. Once they hit the 3800 and above rpm their car stumbles. They said the culprit is their secondary injectors not activating because of bad resistor. Please help and thank you all.

 

How did you conclude that it was initially the 5th and 6th ports not working as they should? There is an easy way of testing the actuating of the ports which involves using grease on the actuator rods. The rods pull in when actuated and if the grease moves from its initial position then this tells you the rods were moving. Is this what you did and if you did do this did you do this test while driving around at higher rpm's or just reving the car in neutral?

And most stumbling at 3800 is a product of poor grounding which prevents the secondary injectors from turning on when they are supposed to.

 

@ Satch Yes I have done that tests and it didn't move at all, got it from Aaron's page followed. Again, I floored the accelerator and drove the car hard. Ground is not an issue because when I rebuilt the engine I sanded most of my contact points, I have read about the 3800 hesitation. Thanks Satch for your help, if I am missing some steps please don't hesitate to let me know.

 

BTW where exactly do I need to probe the injectors with my stethoscope to hear it pulsates?

 

it could be a bad injector connector or stuck injector as well.

 

You need to trick the car into thinking it is under load. Disconnecting the TPS plug and unplugging the vacuum hose to the Pressure Sensor will achieve this thus reving the car in neutral will allow you to activate the secondary injectors. Placing the scope on any part of the exposed secondary injector should do it, but it clicking is not a scott free way of telling if that causes you to look at other things. As j9 suggests it could also be the things he suggested. A clogged cat could also cause this problem in addition to a fuel pump related issue.