S4 Turbo II no injector pulse
 

So my car has been undergoing a bit of work over the past few months. Nothing terribly major, but I've run into an issue at this point.
I have a Power FC and Banzai Racing adapter harness and when I attempt to start the engine the injectors are not pulsing despite the Power FC showing it's percieved duty cycle.

Here's what I have done so far in an attempt to correct the issue:

• Verified that the Power FC is not faulty
• Replaced the engine harness with a new OEM one
• Replaced the injectors with new DW units
• Checked the "eng inj" fuse and it's not blown
• Checked the resistors in the resistor pack and they are within spec (6.3 ohms)

I've also cleaned all of my grounds besides the starter ground. I have fuel pressure while cranking and a very strong spark from the coils. I cannot figure out whats going on, absolutely no fuel sprays from the primaries during start up. Prior to the Power FC install, I was having an issue with the engine bucking while under light load which I thought was TPS related (replaced with a new one now).
Never had any issues starting and idling though, just random lean spots while going over bumps and turning. Also if I had the car idling to operating temp, I would open the door and sit down and it would die as if the engine was out of fuel and then start right back up no problem (I figured this was related with the issue of going lean over bumpy roads, hence the reason I replaced the old broken harness thinking there was a short).

Any ideas? I'm stumped.

Thanks,
Steven

Have you verified 12V at the injectors with the key on IGN?

No I have not. Will I have to remove the upper intake manifold to verify at the connectors or should I probe wires elsewhere? Which pins are proper to check at the ecu? I don't have my manual handy (at work).

Probe at the respective ECU pins. 3C, 3F, 3E and 3H.

I will do this after work and post the results.

Thank you

Check voltage at the injector connectors. The PFC only supplies ground to open the injectors.

Also since you have a PFC the injector wire are 4W, 4X, 4Y, 4Z, but again that is not for checking voltage.

Pull the UIM, use a spare injector connector on the injectors and supply 12V & ground , listen for a click on each and check for spray on the secondaries.

Fuel pump should prime as soon as you turn the key to the on position, it should not just have fuel pressure while cranking. Double check your connection to the COR.

I will try this method when it cools down a bit outside. As far as the fuel pump is concerned, it primes when the key is switched on and then runs as it should during cranking.

Thanks

Still no luck. I checked each injector for a click and there's no issue with them. Is there anything in the harness that would cause my above mentioned symptoms (original post prior to pfc install) and then in turn prevent the ground pulse from making the injectors open after the pfc install? The car ran prior to this, just had an odd grounding issue or maybe a short somewhere.

Are you focusing on the primary injectors as the secondaries don't work unless under load and above 3800 rpm.

Do you have spark while cranking?

Happen to have a spare crank angle sensor? Plug it in, spin it and see if you hear the injectors work.

I do have spark while cranking also I have a spare cas on another engine actually. I'll do this now.

I spun the cas and I could here the injectors working (clicks and mainly hissing sounds from each as I spun it). I installed that cas and tried the same method with the original one, same results. I then tried to crank the car with my extra one, no start.

Are you certain that you are getting fuel?

Sounds like you are losing voltage to the ECU or the injectors while cranking. Power to the injectors comes from the main relay.

If the main relay was bad, the fuel pump wouldn't prime with key on correct? Could a CPU cold solder issue cause these symptoms? The warning light clock worked when it wanted to and my horn function was intermittent as well.

Thank you

Edit: the clock's issue is in the warning light panel itself, but the horn's intermittent issue could be related to the odd loss of power going over bumps in the road if the CPU points need to be re-soldered correct?

CPU doesn't play a role. And in a stock situation w/the key to on the Engine fuse powers the Circuit Opening Relay which powers the pump.

Ah, thank you for the insight. As far as your previous post, I am certain I am getting fuel. I tested this by removing the feed line and having the car turn over. As far as the main relay is concerned, I will purchase another now then and see what happens when it arrives.

Thanks

In my past comment I meant to say "w/the car running and the key to on." But if you want to bypass the Main Relay all you would need to do is remove the four wire plug to the relay, which has two plugs in all, and jumper the B/G to B/Y and B/W to W/L. You can then see if the relay was faulty and thus the cause of your problem although don't leave the jumpers in place as this could eventually drain the battery.

Fuel pump will prime since you are getting power to the ECU and COR with the key in the on position, ths issue appears to be when you turn the key to start. This is when it is critical that the power to the ECU does not get interupted. Power is supplied by the main relay to pin 1C.

A quick test is to push start the car. If it starts and runs then you have narrowed down your search. Keep in mind that all the fuel injector testing has dumped a lot of fuel into your engine.

I attempted to push start the car a couple of times with no luck starting it. I also replaced the main relay anyway just in case. Is there anything else that would interfere with power getting to the ECU during start up? Thank you and Satch both for your help so far.

Have you checked the voltage at pin 1C (for your aftermarket Power FC) w/key to start? The voltage should be 12 volts w/key to on but upon startup the voltage would drop as voltage is supplied to the starter. Voltage would normally drop down to around 9 volts or so. If it is too low then it might not be enough to power the PFC thus causing your problem.

It drops to about 10.5 V while the car is attempting to start according to the Power FC.

The voltage should be more than adequate.

Have your primary injectors ever worked properly after the installation of the PFC?

No they have not. Since installing it, the car will not start. I thought it was the fault of the Power FC originally so I had it tested in a FD locally and the car started up no problem. I followed the instructions very closely and verified that my wiring was correct after recieving the adapter harness.

The FD car you tested it in I would assume had a PFC to begin with and you just switched yours for the existing one?