I have a S5 gxl / T2 swap. I couldn't get it to stay running and it just kept backfiring but I fixed a couple of problems and it runs now.
The problem is it runs really bad. It sounds like its running on one rotor. Compression on all six faces of the rotors is 90-95. I pulled the plug boots off and there is spark to all four plugs. It has a new Walbro 255 fuel pump. Timing is dead on.
Any ideas?

 

I was thinking along the lines of maybe its a coil problem so I went to the lead coil and check for voltage on the black/yellow wire and I had 12v.

Next I went to the green/yellow wire that is supposed to go from 0 volts to 5 volts as the engine is turned over but I got 0 volts. It didn't change as I turned the motor over.
IF that is true, should it even run? Running on trailing coil only?

 

Since the engine can run on just the leading coil only you can disconnect the trailing coil connectors (two of them) and try to start/run the car w/o the trailing coil.

 

I disconnected the trailing coil and the engine will start but only runs a few seconds. I checked across the terminals on the leading coil and the resistance was .2 ohms. So, its time to look for a new trailing coil?????

ashley

 

Yes/No. Why didn't I a change in voltage on the green/yellow trigger wire from the ECU?

 

When you tested for voltage on the G/Y wire was the key to on? Did you also hand crank the engine which is necessary to get a reading. If you did both of these things then you should have observed a proper reading. If not, then you can perhaps get a reading at the ECU instead to see what's up.

The car should not die just from running on the leading coil. I would focus on getting the car running under this scenario.

 

check for vacuum leaks at the turbo induction housing and intake tubing.